Home Effect of cerium on the initiation of pitting corrosion of 444-type heat-resistant ferritic stainless steel
Article Open Access

Effect of cerium on the initiation of pitting corrosion of 444-type heat-resistant ferritic stainless steel

  • Mingyu Ma , Houlong Liu and Liqing Chen
Published/Copyright: November 9, 2020
Download Article (PDF)
Become an author with De Gruyter Brill
Submit Manuscript Author Information
High Temperature Materials and Processes
From the journal High Temperature Materials and Processes Volume 39 Issue 1

Abstract

The 444-type heat-resistant ferritic stainless steel is widely utilized in automotive exhaust pipes and solid oxide fuel cells, due to its excellent properties at elevated temperature. To meet the demands of significantly harsh service environments, rare earths were added in 444-type ferritic stainless steel. For the purpose of evaluating the effect of rare earths on pitting corrosion initiation, the metastable pitting corrosion behavior in 444-type ferritic stainless steel was studied through potentiodynamic polarization and potentiostatic polarization tests. The results demonstrated that pitting corrosion was initiated at the inclusion/alloy interface. The cerium alloying in 444-type ferritic stainless steel decreased the amount of preferential dissolution sites. The beneficial effect of Ce on pitting corrosion resulted from the formation of stable cerium oxides, as well as from the reduction in the amount and size of inclusions in 444-type ferritic stainless steel. In addition, electrochemical impedance spectroscopy test results revealed that cerium alloying enhanced the polarization resistance of passive films through insignificant thickness alteration.

Keywords: 444-type ferritic stainless steel; cerium; inclusions; metastable pitting corrosion

1 Introduction

The 444-type ferritic stainless steel demonstrates satisfactory mechanical properties, such as favorable anti-corrosion performance, along with high thermal conductivity coefficients and moduli of elasticity. Combined with low costs, ferritic stainless steel has proved to be popular for various applications and, in result, is classified second only to austenitic stainless steel. The 444-type ferritic stainless steel contains Ti and Nb as stabilization elements, proving to be relatively new economical stainless steel [1,2,3]. The Cr and Mo contents maintain the corrosion resistance, while the addition of Ti and Nb improves the weldability compared to conventional ferritic stainless steel. Otherwise, owing to the advanced steelmaking technology, extremely low C + N concentration was achieved, resulting in satisfactory properties of processing [4]. Considering the excellent performances in these aspects, 444-type ferritic stainless steel was adopted to serve as the main material of automobile exhaust systems. Automobile exhaust systems directly connected to engines sustain working temperatures up to 900°C. Moreover, to achieve the purpose of environmental protection, new standards demanding lower auto emissions were formulated. In order to meet the new standards, the operating temperature of 444-type ferritic stainless steel exceeds 950°C. Consequently, the development of new generation ferritic stainless steel, to ensure the lifetime and safety of gas emission systems, has become an existing problem.

Rare earths are reported to enhance the performance of materials under high-temperature conditions for manifolds. Previous studies have demonstrated that rare earths in stainless steel improved the oxidation resistance through scale adhesion increase, while reducing the oxidation rate and modifying the microstructure [5]. It was also disclosed that rare earths modified the type and shape of inclusions, which had a positive effect on the mechanical properties of steel. Other researchers in the authors’ group revealed the beneficial effect of Ce on anti-oxidation performance and strength at high temperatures [6,7,8,9,10,11]. However, manifold structures sustained the attack of chloride ions, which also resulted in pitting corrosion. Kim et al. found that the addition of Ce in austenitic stainless steel improved the Cr-deletion of (Fe, Cr) oxide inclusions and led the pits to grow towards the alloy matrix, consequently increasing the pitting corrosion resistance [12]. The most commonly known positive influence of rare earths is the suppression effect on the detrimental sulfide formations that act as the initiation sites of pitting [13].

However, few studies specifically aimed to study the effect of rare earths on the inclusions and corrosion behavior of 444-type ferritic stainless steel. Therefore, it was necessary to study the relationship between inclusions and corrosion behavior in 444-type ferritic stainless steel containing rare earths. In this study, the effects of cerium on the morphology, composition and distribution of the inclusions were investigated. Accordingly, the mechanism affecting the pitting initiation was also discussed, based on electrochemical corrosion measurements and inclusion surface morphology observation.

2 Experimental

The experimental stainless steel samples were prepared through atmospheric melting in a high frequency induction furnace. The elemental compositions of the test ferritic stainless steel samples are listed in Table 1. The cold rolled steel samples were annealed at 1,050°C for 1 min and subsequently cut into samples of 10 mm × 10 mm dimensions. The samples were ground with SiC paper down to 2,000 grit and polished with diamond paste of 1.5 µm. Furthermore, the samples were cleaned with acetone and hot water. Finally, the samples were dried at room temperature.

Table 1

Chemical compositions of ferritic stainless steel samples (wt%)

SteelCSiMnPSCrNbTiNMoCeWFe
FSS10.0060.540.330.0060.00619.70.4360.1740.00722.09——Bal.
FSS20.0090.520.320.0080.00819.50.4500.1550.00721.970.048—Bal.

The samples for electrochemical measurements were joined with a copper wire and consequently mounted with epoxy resin, while one exposed surface was left as the working electrode. Also, a Pt plate acted as the counter electrode, and a saturated calomel electrode (SCE) was the reference electrode. The potentiodynamic polarization tests were conducted in the potential range of −0.25 VOCP to 1.0 VSCE, with a scanning rate of 0.5 mV/s. The current transients through the potentiostatic polarization were measured at a potential within the passive region for 3,000 s. The electrochemical impedance spectroscopy (EIS) analysis was conducted following stabilization at the open circuit potential (OCP) for 10 min. The signal was produced through scanning from 100 kHz to 10 mHz with an AC amplitude of 10 mV. The EIS data were analyzed with the ZSimpWin software with a suitable equivalent electrical circuit. Prior to each electrochemical measurement, the exposed surface was cathodically polarized at −1.0 VSCE for 10 min, to eliminate the oxides formed in air to ensure reproducible conditions. Electrochemical experiments were performed with a 10% NaCl solution at 25°C. All tests were repeated at least three times to verify reproducibility.

The surface morphology after potentiodynamic polarization was observed through scanning electron microscopy (SEM). The elemental distribution and morphology of inclusions were analyzed through electron microprobe analysis (EPMA).

3 Results and discussion

3.1 Influence of cerium on inclusions

Figure 1 presents the SEM back-scattered electron images of the inclusions in ferritic stainless steel. It could be observed that the amounts and sizes of the black spots in FSS1 were lower than those of FSS2, while the inclusions in rare earth alloys appeared spherical in shape. Therefore, it could be deduced that the addition of cerium in 444-type ferritic steel samples reduced the area of inclusions on the exposed surface and modified the shape of inclusions. Certain researchers demonstrated that the pits, which nucleated at small-sized inclusions (<1 µm), hardly turned to stable pits [14]. Furthermore, the lifetime of a metastable pit formed at an inclusion was reported to be directly affected by the dimensions of the inclusion [12]. In addition, the pitting potential relied on the performance of the largest-sized inclusion existing in the alloy.

Figure 1 Back-scattered electron images of inclusions in ferritic stainless steel samples: (a) FSS1 and (b) FSS2.
Figure 1

Back-scattered electron images of inclusions in ferritic stainless steel samples: (a) FSS1 and (b) FSS2.

Besides the passivity of the alloy and the aggressive conditions, the distribution and elemental composition of inclusions proved to be an important factor in the nucleation initiation of metastable pits. Characterization of the inclusion was carried out through EPMA. The typical morphology images and elemental maps of inclusions are presented in Figures 2 and 3. As it could be observed, the inclusions in 444-type ferritic stainless steel were composed of (Mg, Al) oxides and (Mg, Al, Ca) oxides, while the inclusions in Ce alloyed steel samples were mainly Ce oxides. In view of thermodynamic analysis, the standard free energy of formation for rare earth oxides was lower than that of other metallic oxides. This signified that the affinity of cerium for oxygen was higher than that of Al and Mg. Consequently, Ce2O3 was preferentially formed in cerium-containing alloys [13]. Zheng et al. [15] investigated the oxide inclusions through scanning Kelvin probe force microscopy (SKPFM). The analysis suggested that the sites of (Mg, Al, Ca) oxide inclusions presented remarkably low Volta potentials, which indicated a higher corrosion tendency than that of the matrix. However, the potential difference value between rare earth oxides and the matrix was significantly lower than that between (Mg, Al) oxides and the matrix. Consequently, (Mg, Al, Ca) oxides and (Mg, Al) oxides could act as anode phases, due to the higher electrode potential difference causing micro-galvanic corrosion, while the rare earth oxide stability was similar to that of the passive film on the surface.

Figure 2 EPMA images of elemental distribution of inclusions in FSS1 steel.
Figure 2

EPMA images of elemental distribution of inclusions in FSS1 steel.

Figure 3 EPMA images of elemental distribution of inclusions in FSS2 steel.
Figure 3

EPMA images of elemental distribution of inclusions in FSS2 steel.

3.2 Effect of cerium on passive film stability

Figure 4 presents the EIS plots of experimental specimens, stabilized at the OCP for 10 min in 10% NaCl. The semicircle arcs in Nyquist plots implied similar capacitance behavior of both specimen surfaces, which revealed the formation of stable passive films on the samples. The appearance of a conductive arc was related to the charge transfer under the electric field influence, while its radius was proportional to the resistance to charge transfer at the work electrode/electrolyte interface. The overall impedance value increase predicted the enhancing effect of cerium on the passive film stability at the OCP. The passivity of the film formed on the stainless steel surface in the corrosive environment had a high impact on both samples, as well as on the propagation of metastable pits [16]. Inclusions on the stainless steel surface might lead to continuity interruption or weak microzones of the passive film caused by Cr depletion. When the samples were exposed to NaCl solution, the bare matrix was in contact with aggressive ions directly, resulting in the formation of active sites in the passive films on stainless steel samples. The addition of cerium decreased the Cr-depleted zone area caused by inclusions, which signified the barrier layer free zone reduction. Furthermore, localized EIS was utilized to measure the impedance around active inclusions during corrosion. The results revealed that the impedance at the inclusion/matrix interface was lower than that of the inclusions. Therefore, the positive effect of rare earths was related to the modification effect on inclusions.

Figure 4 Nyquist plots of experimental steel samples in 10% NaCl solution.
Figure 4

Nyquist plots of experimental steel samples in 10% NaCl solution.

For further study of the passivated metal surface, different equivalent circuits were proposed by researchers. The R(Q(R)) model presented in Figure 4 was employed to fit the impedance data. According to previous studies [17], this equivalent circuit was suitable to model the behavior of steel and stainless steel in neutral NaCl solution. And compared to other equivalent circuits, this model gave the best fitting parameters. In this fitting system, Rs, Rct and Q represented the resistance of solution, the charge transfer resistance and the capacitance behavior of the barrier, respectively. For this model, it was assumed that the impedance response was related to the passive film conductivity, while the oxide barrier growth mechanism was independent of the immersion time. With consideration of the dispersion effect resulting from the alloy surface roughness, a constant phase element (CPE) was used rather than the ideal capacitor C to describe the surface capacitance. The admittance of the CPE was defined as follows [18]:

(1)Y=Y0(iω)n,

where Y0 is the constant representative for the CPE, n is an adjustable parameter for the CPE and ω is the angular frequency. Also, i2 = −1. The values of n were close to 1, revealing that a capacitor was established on the surface [19]. Once the values of Y0, Rct and n were fitted from the equivalent circuit, the capacitance of the passive film could be obtained through the following equation [18,20]:

(2)C=(Y0Rct)1nRct.

Subsequently, the thickness of the space charge layer formed on the alloy could be roughly obtained through the following equation [20]:

(3)L=εε0AC,

where ε0 is the permittivity of vacuum (8.85 × 10−12 F m−1), ε is the dielectric constant (15.6), A is the exposed area and C is the capacitance of the barrier layer. The estimated values of L are listed in Table 2.

Table 2

Fitting parameters of EIS data from an equivalent circuit

SteelRs (Ω cm2)Y0 (F cm−2)Rf (Ω cm2)nC (Ω−1 cm−2 sn)L (nm)
FSS16.382.8 × 10−41.5 × 1040.893.34 × 10−40.0413
FSS25.882.2 × 10−42.3 × 1040.872.81 × 10−40.0491

3.3 Effect of cerium on pitting corrosion resistance

The potentiodynamic polarization plots of the experimental stainless steel in 10% NaCl solution at 30°C are presented in Figure 5. In general, the pitting potential Ep is defined at the point where the passive film is destroyed, characterized by the continuous current density increase. Ep is a key parameter to evaluate the resistance to pitting corrosion of stainless steel in aggressive solution [21]. The higher Ep was a result of a more stable stainless steel surface. The anti-corrosion performance of FSS1 was inferior to that of FSS2, because the pitting potential of FSS2 (Ep: 621 mV) was quite higher than that of FSS1 (Ep: 389 mV).

Figure 5 Potentiodynamic polarization curves of experimental steel samples in 10% NaCl at 25°C.
Figure 5

Potentiodynamic polarization curves of experimental steel samples in 10% NaCl at 25°C.

In the potentiodynamic polarization curves, transients were observed at the passive regions of both experimental stainless steel samples. The fluctuation of current in the passive region was attributed to the competitiveness of dissolution/repassivation of the metastable pits at unstable positions, such as inclusions [22]. In this work, the measured metastable pits on the surface were mainly related to the stochastically distributed inclusions. At potentials lower than the pitting potential, the metastable pits could nucleate and propagate, but could not continuously dissolve while the pit surface would sustain repassivation [23]. As the applied potential increased, the dissolution activity of the metal gradually increased and the metastable propagation of the pit was facilitated. Consequently, the probability that a metastable pit turned to a stable pit was enhanced [24]. Finally, the critical conditions for stable dissolution were approached and metastable pits would continuously propagate, ultimately becoming stable [25]. As the stable pitting nucleation was related to metastable pitting growth, it was predicted that the inclusion might also influence the development of metastable pitting, thereby affecting the pitting sensitivity of the alloys.

The pitting potential was primarily dependent on the interaction between repassivation and dissolution of metastable pits. For the experimental alloys, the evident resistance increase to pitting corrosion might be explained by the effect of rare earths on the inclusions: when no favorable position for metastable pitting nucleation existed on the FSS1 surface due to fewer inclusions, the Ep would be higher due to the stable passive film; however, more active inclusions existed on the FSS2 surface, for which, the occurrence of stable pitting might be evident at more negative potentials.

The corrosion morphologies of ferritic stainless steel following potentiodynamic polarization in 10% NaCl solution are presented in Figure 6. The growth of stable pitting corrosion could be separated into several steps [1]: primarily, local dissolution was initiated, due to less protectivity of the passive film at inclusions. Under most circumstances, the metastable pits would be repassivated following short propagation. Only the pits that did not participate in metastable propagation could be observed as stable pits. As it could be observed from Figure 6, additional dissolved pits existed on the FSS1 surface, which indicated that additional metastable pits were stabilized on conventional 444-type ferritic stainless steel.

Figure 6 SEM morphology of pitting corrosion after potentiodynamic polarization. (a) FSS1 and (b) FSS2.
Figure 6

SEM morphology of pitting corrosion after potentiodynamic polarization. (a) FSS1 and (b) FSS2.

The pits on ferritic stainless steel behaved as hemispherical cavities, and porous covers were left on the pit mouths. This occurred because the metastable pits nucleated at the inclusions, after the residual passive films and salt films over the pit ruptured, while further dissolution undercut the passivated surface [26]. Moreover, the dissolution of metal was more intense within the pits, due to the lower energy barrier of metal cations breaking away from the exposed matrix than that of those from the passive film. Therefore, the metal cations enriched the bottom of pits, resulting in a concentration gradient along the pit depth, and the solution adjacent to pit mouth was diluted. Stainless steel has a defined critical dissolved metal cation concentration, below which, the high current density required for dissolution stability cannot occur [27]. Following this emergence, the holes on the cover continued growing for a certain amount of time under the effect of osmotic pressure [28]. When the pit reached a critical size, the pit cover was destroyed, leaving an open hemispherical cavity.

3.4 Effect of cerium addition on pitting nucleation

It has been reported that pit nucleation occurs even on passivated surfaces. However, most nucleates, which are defined as metastable pits, could be repassivated, whereas only a few nucleates could grow continuously to stable pits. When a pit nucleation occurs, the current increases sharply over the background level and suddenly drops to the background current again [29]. This current transient is caused by the dissolution of active sites; therefore, the number of current spikes directly reflects the distribution of pit nucleation on steel surfaces. According to the characteristic feature of the polarization curves, the potential between 0 and 0.4 VSCE was determined to be within passive range for all specimens. A single applied potential of 0.2 VSCE was selected for film growth, at which, all specimens were well passivated. The potentiostatic polarization curves for the ferritic stainless steel in 10% NaCl solution at 30°C with an applied potential of 0.2 VSCE are presented in Figure 7. The current transient was recorded to analyze the nucleation and repassivation of metastable pits on the experimental stainless steel samples. It could be observed from Figure 7 that the current density plots polarized at passive potential were not drawn as smooth curves, whereas current spikes corresponding to the metastable pits were detected. The current increase originated from the active dissolution of the surface, while the subsequent current drop indicated the repassivation of the inner surface of the pit [30]. As Ce was alloyed in ferritic stainless steel, the current spikes for initiation and repassivation of the metastable pits were increasingly frequent. Consequently, it could be concluded that the resistance to nucleation of pitting corrosion increased through rare earth alloying.

Figure 7 Potentiostatic polarization curves of experimental steel samples in 10% NaCl at 25°C. (a) FSS1 and (b) FSS2.
Figure 7

Potentiostatic polarization curves of experimental steel samples in 10% NaCl at 25°C. (a) FSS1 and (b) FSS2.

The average value of current peaks of FSS1 was higher than that of FSS2, revealing a more intense dissolution of pits on FSS1. In the early stage of metastable pit formation, the pit growth was determined by the migration of metal ions far away from the dissolved pit. Higher current peak values characterized higher dissolution rates and highly dissolved volumes. The higher depth of pits produced a more effective diffusion barrier to support the critical composition of solution required for pit propagation.

On the other hand, the relatively high dissolution rate of metal decreased the lifetime of metastable pits. The process of metastable pit formation consisted of the local destruction of the passive film, along with bare matrix dissolution and pit repassivation. The additional dissolution of metal resulted in higher metal cation concentration; subsequently, the residual passive film and salt film over the pit would break faster, due to the osmotic pressure caused by concentration difference [16]. Consequently, the addition of cerium reduced the probability of metastable pit stabilization.

Figure 8 presents the surface morphology of ferritic stainless steel after potentiostatic polarization at 0.2 VSCE. As it could be observed from Figure 8, the pit nucleation was initiated at the boundary between inclusions and bulk alloy, which was characterized by a bright area around the inclusions. The decrease in the amount of dissolved inclusions indicated the suppression of active site formation, which was in agreement with the potentiostatic polarization curve. Due to the difference in coefficients of thermal expansion, microcrevices were formed on the boundary between the inclusions and the matrix. The SKPFM analysis demonstrated that a potential drop existed between inclusions and matrix. Subsequently, the microchemical capillary study indicated that the highest electrochemically active site was located at the inclusion/matrix interface rather than at the inclusions itself. It was demonstrated that the boundary between the inclusions and the bulk alloy supplied a preferential dissolution site for pitting corrosion. In addition, stainless steel alloying with a mix of rare earths reduced the size and density of inclusions, thereby enhancing the resistance to pitting corrosion. Fewer nucleation sites existed in FSS2. Consequently, the initiations of metastable pitting or even stable pitting on rare earth alloyed stainless steel were more difficult than on conventional 444-type ferritic stainless steel.

Figure 8 Surface morphology of samples after potentiostatic polarization. (a) FSS1 and (b) FSS2.
Figure 8

Surface morphology of samples after potentiostatic polarization. (a) FSS1 and (b) FSS2.

Factors, such as an aggressive environment and material conditions, which would control the growth and repassivation of metastable pitting had high impact on pitting. It was clear that the formation of stable pitting was a result of the metastable pitting development. This fact indicated that the inclusions might also affect its stabilization. The morphology and composition of inclusion induced dissolution after potentiostatic polarization testing were observed to explore the detailed relationship, as presented in Figures 9 and 10. Regarding the FSS1 sample, metastable pitting corrosion was initiated at the inclusion/matrix boundary, such as at (Mg, Al) oxides. The pitting corrosion of the experimental steel alloyed with rare earths was not initiated around the rare earth oxides, but it was initiated around the TiN inclusions. In other words, rare earth oxides did not act as pitting initiation sites in 444-type ferritic stainless steel. Therefore, this suggested that in ferritic stainless steel, the resistance to active solution of the interface at (Mg, Al) oxides/matrix was lower than that of the Ce oxides/matrix interface. The Volta potential difference value between (Mg, Al) oxides and the bulk alloy was quite higher than that between Ce oxides and the matrix. Due to the lower electrode potential difference, Ce oxides could not behave as an anode phase to create the acceleration effect on corrosion nucleation [31,32]. In a previous investigation, the pitting corrosion of rare earth metal (REM)-containing hyperduplex stainless steel did not initiate at REM oxides, improving the anti-corrosion property [12]. In summary, Ce had a positive influence on the initiation of pitting corrosion by affecting the morphology and stability of inclusions, which induced pitting corrosion in chloride ion containing solution.

Figure 9 Images of pit morphologies in FSS1 after potentiostatic polarization in 10% NaCl solution.
Figure 9

Images of pit morphologies in FSS1 after potentiostatic polarization in 10% NaCl solution.

Figure 10 Images of pit morphologies in FSS2 after potentiostatic polarization in 10% NaCl solution. (a) Ce oxide; (b) TiN.
Figure 10

Images of pit morphologies in FSS2 after potentiostatic polarization in 10% NaCl solution. (a) Ce oxide; (b) TiN.

3.5 Mechanism of pitting corrosion initiation

According to these results, the mechanism of nucleation and propagation of the pitting corrosion induced by (Mg, Al) oxide inclusions in solution containing Cl− is schematically illustrated in Figure 11. As presented in Figure 11(a), the passive films on inclusions were interrupted, while the matrix in microcrevices exhibited lower surface potential than the passive film. When the stainless steel was exposed to NaCl solution, the active Cl− could be adsorbed on the alloy surface and inclusions (Figure 11b). As reported in previous studies, the passive films around inclusions acted as cathodes, due to higher surface potential, whereas the active metal with lower surface potential in microcrevices became the anode phase [23]. Therefore, the active–passive galvanic corrosion caused by the difference in surface potentials occurred (Figure 11c). The anodic and cathodic reactions during the early stage of the metastable pitting in the stainless steel might have occurred as follows:

Figure 11 Mechanism of initiation and propagation of pits nucleated at inclusions in solution containing chloride ions. (a) Microcrevices between inclusion and matrix; (b) Cl− adsorbtion; (c) Formation of galvanic corrosion; (d) Nucleation of metastable pit; (e) Formation of closed autocatalysis corrosion cell; (f) Dissolution of matrix.
Figure 11

Mechanism of initiation and propagation of pits nucleated at inclusions in solution containing chloride ions. (a) Microcrevices between inclusion and matrix; (b) Cl− adsorbtion; (c) Formation of galvanic corrosion; (d) Nucleation of metastable pit; (e) Formation of closed autocatalysis corrosion cell; (f) Dissolution of matrix.

Anodic reaction at the matrix in microcrevices:

(R1)Fe→Fe2++2e−,
(R2)Cr→Cr3++3e−.

Cathodic reaction at the film/solution interface:

(R3)Fe2O3+H2O+e−→Fe+OH−,
(R4)Cr2O3+H2O+e−→Cr+OH−.

Several cationic Men+ species were generated from the anodic reaction, while further hydrolysis reaction of these ions evolved according to formulae (R5) and (R6):

(R5)Fe2++H2O→Fe(OH)2+H+,
(R6)Cr3++H2O→Cr(OH)3+H+.

The H+ produced by the hydrolysis reaction of metallic ions lowered the pH of the solution in the microcrevices. Subsequently, the (Mg, Al) oxide inclusions were dissolved in the acidic corrosive solution. Furthermore, as the dissolution occurred at the pit bottom, while the cathodic reaction occurred at the oxide film around the inclusions, the local accumulation of chloride anions within the microcrevices was the natural consequence to maintain the electro-neutrality of the electrolyte. As a consequence, the concentration increase of Cl− and reduction of pH value within pits amplified the dissolution development and prevented the pit surfaces from passivating. As the concentration of dissolving metal cations increased in the pit, a certain amount of cations migrated to the bulk solution from the pit interior and reacted with OH− at the pit mouth (Figure 11d). The insoluble corrosion production was laid at the pit mouth. This circular process resulted in a closed autocatalysis corrosion cell (Figure 11e) [33]. As is well known, in order to maintain the dissolution activity of metal on the pit side wall as induced by chloride ions, a specific corrosive environment, such as a lower pH value and/or concentrated chloride ions, must exist. As the potentiostatic polarization evolved, the concentration of cations increased with the alloy dissolution. Finally, the osmotic pressure caused by the concentration gradient resulted in the breakdown of the corrosion product cover on the pit mouth. Therefore, the corrosive electrolyte within the pit was diluted and the matrix was repassivated (Figure 11f).

Generally, the metastable pits tend to passivate again at passive potential, although the inclusion might dissolve completely with time. However, during potentiodynamic polarization, the ability of repassivation is insufficient to maintain protection, and therefore, the passive layer might be destroyed and a stable pit formed. The formation of corrosion pits was identified through distinct procedures kinetically: nucleation, metastable propagation and stable growth. Through the results summary, the effect of inclusions caused by rare earths on the initiation and propagation of metastable pitting corrosion in ferritic stainless steel is presented.

The improvement in anti-corrosion ability caused by Ce alloying was most likely related to the inclusions in Ce-alloyed 444-type ferritic stainless steel. This beneficial effect could be clarified on the basis of three important aspects. First, the addition of Ce to 444-type ferritic stainless steel refined the coarse inclusions and purified the matrix through inclusion amount reduction. Second, inclusion dimensions contribute to the initiation and repassivation of metastable pits through the decrease of microcrevices between the bulk alloy and the inclusions, which acted as pit initiation sites. Finally, the addition of Ce to 444-type ferritic stainless steel led to the presence of stable Ce oxides, which improved the resistance to pitting corrosion.

4 Conclusions

The influence of Ce-modified inclusions on the initiation and propagation of pitting corrosion in 444-type ferritic stainless steel was studied. The following conclusions can be drawn.

  1. The addition of Ce rare earth improved the pitting corrosion resistance of 444-type ferritic stainless steel due to the decrease in the amount and size of inclusions. The positive effect of rare earths on resistance to pitting corrosion initiation was related to the type and amount of inclusions in 444-type ferritic stainless steel.

  2. The protective passive film was enhanced by Ce addition, which contributed to the amount reduction of weak sites, caused by inclusions within passive films. However, the passive film thickness did not significantly increase in Ce-containing ferritic stainless steel.

  3. The addition of Ce led to the formation of rare earth oxides, which did not act as active sites during pitting corrosion, while the (Mg, Al) oxide and (Mg, Al, Ca) oxide inclusions in 444-type ferritic stainless steel samples induced pitting corrosion.

  4. The pitting corrosion for both experimental alloys occurred at the interfaces between inclusions and bulk alloy, while the addition of rare earths suppressed the number of preferential dissolution positions, as well as the stable pits in 444-type ferritic stainless steel.

Acknowledgments

The authors are grateful for the financial support from the National Natural Science Foundation of China and Baowu Steel Group Co., Ltd (Grant No. U1660205).

References

[1] Bitondo, C., A. Bossio, T. Monetta, M. Curioni, and F. Bellucci. The effect of annealing on the corrosion behaviour of 444 stainless steel for drinking water applications. Corrosion Science, Vol. 87, 2014, pp. 6–10.10.1016/j.corsci.2014.06.025Search in Google Scholar

[2] Silva, C. C., J. P. Farias, H. C. Miranda, R. F. Guimarães, J. W. A. Menezes, and M. A. M. Neto. Microstructural characterization of the HAZ in AISI 444 ferritic stainless steel welds. Materials Characterization, Vol. 59, 2008, pp. 528–533.10.1016/j.matchar.2007.03.011Search in Google Scholar

[3] Han, J., H. Li, F. Barbaro, L. Jiang, Z. Zhu, H. Xu, et al. Precipitation and impact toughness of Nb–V stabilised 18Cr–2Mo ferritic stainless steel during isothermal aging. Materials Science and Engineering: A, Vol. 612, 2014, pp. 63–70.10.1016/j.msea.2014.06.029Search in Google Scholar

[4] Yan, H., H. Bi, X. Li, and Z. Xu. Microstructure and texture of Nb+ Ti stabilized ferritic stainless steel. Materials Characterization, Vol. 59, 2008, pp. 1741–1746.10.1016/j.matchar.2008.03.018Search in Google Scholar

[5] Li, X., J. Shu, L. Q. Chen, and H. Y. Bi. Effect of cerium on high-temperature oxidation resistance of 00Cr17NbTi ferritic stainless steel. Acta Metallurgica Sinica (English Letters), Vol. 27, 2014, pp. 501–507.10.1007/s40195-014-0079-6Search in Google Scholar

[6] Wei, L. L., J. H. Zheng, L. Q. Chen, and R. D. K. Misra. High temperature oxidation behavior of ferritic stainless steel containing W and Ce. Corrosion Science, Vol. 142, 2018, pp. 79–92.10.1016/j.corsci.2018.07.017Search in Google Scholar

[7] Wei, L. L., L. Q. Chen, M. Y. Ma, H. L. Liu, and R. D. K. Misra. Oxidation behavior of ferritic stainless steels in simulated automotive exhaust gas containing 5 vol.% water vapor. Materials Chemistry and Physics, Vol. 205, 2018, pp. 508–517.10.1016/j.matchemphys.2017.11.051Search in Google Scholar

[8] Ma, M. Y., C. L. He, H. L. Liu, and L. Q. Chen. Influence of cerium and tungsten addition on the passive behaviour of 444-type ferritic stainless steels. International Journal of Electrochemical Science, Vol. 14, 2019, pp. 2277–2289.10.20964/2019.03.31Search in Google Scholar

[9] Ma, M. Y., C. L. He, L. Q. Chen, L. L. Wei, and R. D. K. Misra. Effect of W and Ce additions on the electrochemical corrosion behaviour of 444-type ferritic stainless steel. Corrosion Engineering, Science and Technology, Vol. 53, 2018, pp. 199–205.10.1080/1478422X.2018.1429701Search in Google Scholar

[10] Liu, H. L., M. Y. Ma, L. L. Liu, L. L. Wei, and L. Q. Chen. Effect of hot band annealing processes on texture and formability of 19Cr2Mo1W ferritic stainless steel. Acta Metallurgica Sinica, Vol. 55, 2019, pp. 566–574.Search in Google Scholar

[11] Liu, H. L., M. Y. Ma, L. L. Liu, L. L. Wei, and L. Q. Chen. Effect of W addition on hot deformation and precipitation behaviors of 19Cr2Mo ferritic stainless steel. Journal of Iron and Steel Research International, Vol. 26, 2019, pp. 425–434.10.1007/s42243-019-00233-xSearch in Google Scholar

[12] Jeon, S. H., S. T. Kim, M. S. Choi, J. S. Kim, K. T. Kim, and Y. S. Park. Effects of cerium on the compositional variations in and around inclusions and the initiation and propagation of pitting corrosion in hyperduplex stainless steels. Corrosion Science, Vol. 75, 2013, pp. 367–375.10.1016/j.corsci.2013.06.020Search in Google Scholar

[13] Yu, Y. C., S. H. Zhang, and S. B. Wang. Effects of cerium on the inclusions and pitting corrosion behavior of 434 ferritic stainless steel. High Temperature Material Processes, Vol. 37, 2018, pp. 807–814.10.1515/htmp-2017-0094Search in Google Scholar

[14] Jeon, S.-H., S.-T. Kim, I.-S. Lee, and Y.-S. Park. Effects of sulfur addition on pitting corrosion and machinability behavior of super duplex stainless steel containing rare earth metals: Part 2. Corrosion Science, Vol. 52, 2010, pp. 3537–3547.10.1016/j.corsci.2010.07.002Search in Google Scholar

[15] Zheng, S., C. Li, Y. Qi, L. Chen, and C. Chen. Mechanism of (Mg, Al, Ca)-oxide inclusion-induced pitting corrosion in 316L stainless steel exposed to sulphur environments containing chloride ion. Corrosion Science, Vol. 67, 2013, pp. 20–31.10.1016/j.corsci.2012.09.044Search in Google Scholar

[16] Naghizaheh, D. N. M., M. Zakeri, and M. H. Maoyed. The effect of dichromate ion on the pitting corrosion of AISI 316 stainless steel Part II: Pit initiation and transition to stability. Corrosion Science, Vol. 94, 2015, pp. 420–427.10.1016/j.corsci.2015.02.025Search in Google Scholar

[17] Ebrahimi, N., M. Momeni, A. Kosari, M. Zakeri, and M. H. Moayed. A comparative study of critical pitting temperature (CPT) of stainless steels by electrochemical impedance spectroscopy (EIS), potentiodynamic and potentiostatic techniques. Corrosion Science, Vol. 59, 2012, pp. 96–102.10.1016/j.corsci.2012.02.026Search in Google Scholar

[18] Luo, H., S. Gao, C. Dong, and X. Li. Passivation and electrochemical behavior of 316L stainless steel in chlorinated simulated concrete pore solution. Applied Surface Science, Vol. 400, 2017, pp. 38–48.10.1016/j.apsusc.2016.12.180Search in Google Scholar

[19] Fajardo, S., D. M. Bastidas, M. Criado, and J. M. Bastidas. Electrochemical study on the corrosion behaviour of a new low-nickel stainless steel in carbonated alkaline solution in the presence of chlorides. Electrochimica Acta, Vol. 129, 2014, pp. 160–170.10.1016/j.electacta.2014.02.107Search in Google Scholar

[20] Feng, Z., X. Cheng, C. Dong, L. Xu, and X. Li. Passivity of 316L stainless steel in borate buffer solution studied by Mott–Schottky analysis, atomic absorption spectrometry and X-ray photoelectron spectroscopy. Corrosion Science, Vol. 52, 2010, pp. 3646–3653.10.1016/j.corsci.2010.07.013Search in Google Scholar

[21] Olsson, C. O. A., and D. Landolt. Passive films on stainless steels—chemistry, structure and growth. Electrochimica Acta, Vol. 48, 2003, pp. 1093–1104.10.1016/S0013-4686(02)00841-1Search in Google Scholar

[22] Pardo, A., M. C. Merino, A. E. Coy, F. Viejo, R. Arrabal, and E. Matykina. Pitting corrosion behaviour of austenitic stainless steels–combining effects of Mn and Mo additions. Corrosion Science, Vol. 50, 2008, pp. 1796–1806.10.1016/j.corsci.2008.04.005Search in Google Scholar

[23] Tang, Y., Y. Zuo, J. Wang, X. Zhao, B. Niu, and B. Lin. The metastable pitting potential and its relation to the pitting potential for four materials in chloride solutions. Corrosion Science, Vol. 80, 2014, pp. 111–119.10.1016/j.corsci.2013.11.015Search in Google Scholar

[24] Li, T., L. Liu, B. Zhang, Y. Li, and F. Wang. Growth kinetics of metastable pits on sputtered nanocrystalline stainless steel. Corrosion Science, Vol. 124, 2017, pp. 46–55.10.1016/j.corsci.2017.04.028Search in Google Scholar

[25] Aouina, N., F. Balbaud-Célérier, F. Huet, S. Joiret, H. Perrot, F. Rouillard, et al. Single pit initiation on 316L austenitic stainless steel using scanning electrochemical microscopy. Electrochimica Acta, Vol. 56, 2011, pp. 8589–8596.10.1016/j.electacta.2011.07.044Search in Google Scholar

[26] Tian, W., N. Du, S. Li, S. Chen, and Q. Wu. Effects of applied potential on stable pitting of 304 stainless steel. Corrosion Science, Vol. 93, 2015, pp. 242–255.10.1016/j.corsci.2015.01.034Search in Google Scholar

[27] Maoyed, M. H., and R. C. Newman. Evolution of current transients and morphology of metastable and stable pitting on stainless steel near the critical pitting temperature. Corrosion Science, Vol. 48, 2006, pp. 1004–1018.10.1016/j.corsci.2005.03.002Search in Google Scholar

[28] Heurtault, S., R. Robin, F. Rouillard, and V. Vivier. On the propagation of open and covered pit in 316l stainless steel. Electrochimica Acta, Vol. 203, 2016, pp. 316–325.10.1016/j.electacta.2016.01.084Search in Google Scholar

[29] Hou, Y., C. Cheng, T. Cao, X Min, and Jie Zhao. Effects of sensitization on the metastable pitting corrosion of 304 stainless steel. International Journal of Electrochemical Science, 2018, pp. 7095–7110.10.20964/2018.07.74Search in Google Scholar

[30] Ha, H. Y., C. J. Park, and H. S. Kwon. Effects of misch metal on the formation of non-metallic inclusions and the associated resistance to pitting corrosion in 25% Cr duplex stainless steels. Scripta Materialia, Vol. 55, 2006, pp. 991−994.10.1016/j.scriptamat.2006.08.014Search in Google Scholar

[31] Kim, S. T., S. H. Jeon, I. S. Lee, and Y. S. Park. Effects of rare earth metals addition on the resistance to pitting corrosion of super duplex stainless steel–Part 1. Corrosion Science, Vol. 52, 2010, pp. 1897–1904.10.1016/j.corsci.2010.02.043Search in Google Scholar

[32] Wang, Y., G. Cheng, W. Wu, and Y. Li. Role of inclusions in the pitting initiation of pipeline steel and the effect of electron irradiation in SEM. Corrosion Science, Vol. 130, 2018, pp. 252–260.10.1016/j.corsci.2017.10.029Search in Google Scholar

[33] Liu, C., R. I. Revilla, Z. Liu, D. Zhang, X. Li, and H. Terryn. Effect of inclusions modified by rare earth elements (Ce, La) on localized marine corrosion in Q460NH weathering steel. Corrosion Science, Vol. 129, 2017, pp. 82–90.10.1016/j.corsci.2017.10.001Search in Google Scholar

Received: 2019-07-11
Revised: 2019-10-15
Accepted: 2019-11-06
Published Online: 2020-11-09

© 2020 Mingyu Ma et al., published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

  1. Research Article
  2. Electrochemical reduction mechanism of several oxides of refractory metals in FClNaKmelts
  3. Study on the Appropriate Production Parameters of a Gas-injection Blast Furnace
  4. Microstructure, phase composition and oxidation behavior of porous Ti-Si-Mo intermetallic compounds fabricated by reactive synthesis
  5. Significant Influence of Welding Heat Input on the Microstructural Characteristics and Mechanical Properties of the Simulated CGHAZ in High Nitrogen V-Alloyed Steel
  6. Preparation of WC-TiC-Ni3Al-CaF2 functionally graded self-lubricating tool material by microwave sintering and its cutting performance
  7. Research on Electromagnetic Sensitivity Properties of Sodium Chloride during Microwave Heating
  8. Effect of deformation temperature on mechanical properties and microstructure of TWIP steel for expansion tube
  9. Effect of Cooling Rate on Crystallization Behavior of CaO-SiO2-MgO-Cr2O3 Based Slag
  10. Effects of metallurgical factors on reticular crack formations in Nb-bearing pipeline steel
  11. Investigation on microstructure and its transformation mechanisms of B2O3-SiO2-Al2O3-CaO brazing flux system
  12. Energy Conservation and CO2 Abatement Potential of a Gas-injection Blast Furnace
  13. Experimental validation of the reaction mechanism models of dechlorination and [Zn] reclaiming in the roasting steelmaking zinc-rich dust process
  14. Effect of substituting fine rutile of the flux with nano TiO2 on the improvement of mass transfer efficiency and the reduction of welding fumes in the stainless steel SMAW electrode
  15. Microstructure evolution and mechanical properties of Hastelloy X alloy produced by Selective Laser Melting
  16. Study on the structure activity relationship of the crystal MOF-5 synthesis, thermal stability and N2 adsorption property
  17. Laser pressure welding of Al-Li alloy 2198: effect of welding parameters on fusion zone characteristics associated with mechanical properties
  18. Microstructural evolution during high-temperature tensile creep at 1,500°C of a MoSiBTiC alloy
  19. Effects of different deoxidization methods on high-temperature physical properties of high-strength low-alloy steels
  20. Solidification pathways and phase equilibria in the Mo–Ti–C ternary system
  21. Influence of normalizing and tempering temperatures on the creep properties of P92 steel
  22. Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites
  23. Improving mechanical properties of ZK60 magnesium alloy by cryogenic treatment before hot extrusion
  24. Temperature-dependent proportional limit stress of SiC/SiC fiber-reinforced ceramic-matrix composites
  25. Effect of 2CaO·SiO2 particles addition on dephosphorization behavior
  26. Influence of processing parameters on slab stickers during continuous casting
  27. Influence of Al deoxidation on the formation of acicular ferrite in steel containing La
  28. The effects of β-Si3N4 on the formation and oxidation of β-SiAlON
  29. Sulphur and vanadium-induced high-temperature corrosion behaviour of different regions of SMAW weldment in ASTM SA 210 GrA1 boiler tube steel
  30. Structural evidence of complex formation in liquid Pb–Te alloys
  31. Microstructure evolution of roll core during the preparation of composite roll by electroslag remelting cladding technology
  32. Improvement of toughness and hardness in BR1500HS steel by ultrafine martensite
  33. Influence mechanism of pulse frequency on the corrosion resistance of Cu–Zn binary alloy
  34. An interpretation on the thermodynamic properties of liquid Pb–Te alloys
  35. Dynamic continuous cooling transformation, microstructure and mechanical properties of medium-carbon carbide-free bainitic steel
  36. Influence of electrode tip diameter on metallurgical and mechanical aspects of spot welded duplex stainless steel
  37. Effect of multi-pass deformation on microstructure evolution of spark plasma sintered TC4 titanium alloy
  38. Corrosion behaviors of 316 stainless steel and Inconel 625 alloy in chloride molten salts for solar energy storage
  39. Determination of chromium valence state in the CaO–SiO2–FeO–MgO–CrOx system by X-ray photoelectron spectroscopy
  40. Electric discharge method of synthesis of carbon and metal–carbon nanomaterials
  41. Effect of high-frequency electromagnetic field on microstructure of mold flux
  42. Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone
  43. Effect of radiative heat loss on thermal diffusivity evaluated using normalized logarithmic method in laser flash technique
  44. Kinetics of iron removal from quartz under ultrasound-assisted leaching
  45. Oxidizability characterization of slag system on the thermodynamic model of superalloy desulfurization
  46. Influence of polyvinyl alcohol–glutaraldehyde on properties of thermal insulation pipe from blast furnace slag fiber
  47. Evolution of nonmetallic inclusions in pipeline steel during LF and VD refining process
  48. Development and experimental research of a low-thermal asphalt material for grouting leakage blocking
  49. A downscaling cold model for solid flow behaviour in a top gas recycling-oxygen blast furnace
  50. Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation
  51. The effect of M (M = Ce, Zr, Ce–Zr) on rolling microstructure and mechanical properties of FH40
  52. Phase evolution and oxidation characteristics of the Nd–Fe–B and Ce–Fe–B magnet scrap powder during the roasting process
  53. Assessment of impact mechanical behaviors of rock-like materials heated at 1,000°C
  54. Effects of solution and aging treatment parameters on the microstructure evolution of Ti–10V–2Fe–3Al alloy
  55. Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel
  56. Dephosphorization of hot metal using rare earth oxide-containing slags
  57. Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method
  58. Optimization of heat treatment of glass-ceramics made from blast furnace slag
  59. Study on microstructure and mechanical properties of P92 steel after high-temperature long-term aging at 650°C
  60. Effects of rotational speed on the Al0.3CoCrCu0.3FeNi high-entropy alloy by friction stir welding
  61. The investigation on the middle period dephosphorization in 70t converter
  62. Effect of cerium on the initiation of pitting corrosion of 444-type heat-resistant ferritic stainless steel
  63. Effects of quenching and partitioning (Q&P) technology on microstructure and mechanical properties of VC particulate reinforced wear-resistant alloy
  64. Study on the erosion of Mo/ZrO2 alloys in glass melting process
  65. Effect of Nb addition on the solidification structure of Fe–Mn–C–Al twin-induced plasticity steel
  66. Damage accumulation and lifetime prediction of fiber-reinforced ceramic-matrix composites under thermomechanical fatigue loading
  67. Morphology evolution and quantitative analysis of β-MoO3 and α-MoO3
  68. Microstructure of metatitanic acid and its transformation to rutile titanium dioxide
  69. Numerical simulation of nickel-based alloys’ welding transient stress using various cooling techniques
  70. The local structure around Ge atoms in Ge-doped magnetite thin films
  71. Friction stir lap welding thin aluminum alloy sheets
  72. Review Article
  73. A review of end-point carbon prediction for BOF steelmaking process
https://doi.org/10.1515/htmp-2020-0001
Keywords for this article
444-type ferritic stainless steel; cerium; inclusions; metastable pitting corrosion
Creative Commons
BY 4.0

Articles in the same Issue

  1. Research Article
  2. Electrochemical reduction mechanism of several oxides of refractory metals in FClNaKmelts
  3. Study on the Appropriate Production Parameters of a Gas-injection Blast Furnace
  4. Microstructure, phase composition and oxidation behavior of porous Ti-Si-Mo intermetallic compounds fabricated by reactive synthesis
  5. Significant Influence of Welding Heat Input on the Microstructural Characteristics and Mechanical Properties of the Simulated CGHAZ in High Nitrogen V-Alloyed Steel
  6. Preparation of WC-TiC-Ni3Al-CaF2 functionally graded self-lubricating tool material by microwave sintering and its cutting performance
  7. Research on Electromagnetic Sensitivity Properties of Sodium Chloride during Microwave Heating
  8. Effect of deformation temperature on mechanical properties and microstructure of TWIP steel for expansion tube
  9. Effect of Cooling Rate on Crystallization Behavior of CaO-SiO2-MgO-Cr2O3 Based Slag
  10. Effects of metallurgical factors on reticular crack formations in Nb-bearing pipeline steel
  11. Investigation on microstructure and its transformation mechanisms of B2O3-SiO2-Al2O3-CaO brazing flux system
  12. Energy Conservation and CO2 Abatement Potential of a Gas-injection Blast Furnace
  13. Experimental validation of the reaction mechanism models of dechlorination and [Zn] reclaiming in the roasting steelmaking zinc-rich dust process
  14. Effect of substituting fine rutile of the flux with nano TiO2 on the improvement of mass transfer efficiency and the reduction of welding fumes in the stainless steel SMAW electrode
  15. Microstructure evolution and mechanical properties of Hastelloy X alloy produced by Selective Laser Melting
  16. Study on the structure activity relationship of the crystal MOF-5 synthesis, thermal stability and N2 adsorption property
  17. Laser pressure welding of Al-Li alloy 2198: effect of welding parameters on fusion zone characteristics associated with mechanical properties
  18. Microstructural evolution during high-temperature tensile creep at 1,500°C of a MoSiBTiC alloy
  19. Effects of different deoxidization methods on high-temperature physical properties of high-strength low-alloy steels
  20. Solidification pathways and phase equilibria in the Mo–Ti–C ternary system
  21. Influence of normalizing and tempering temperatures on the creep properties of P92 steel
  22. Effect of temperature on matrix multicracking evolution of C/SiC fiber-reinforced ceramic-matrix composites
  23. Improving mechanical properties of ZK60 magnesium alloy by cryogenic treatment before hot extrusion
  24. Temperature-dependent proportional limit stress of SiC/SiC fiber-reinforced ceramic-matrix composites
  25. Effect of 2CaO·SiO2 particles addition on dephosphorization behavior
  26. Influence of processing parameters on slab stickers during continuous casting
  27. Influence of Al deoxidation on the formation of acicular ferrite in steel containing La
  28. The effects of β-Si3N4 on the formation and oxidation of β-SiAlON
  29. Sulphur and vanadium-induced high-temperature corrosion behaviour of different regions of SMAW weldment in ASTM SA 210 GrA1 boiler tube steel
  30. Structural evidence of complex formation in liquid Pb–Te alloys
  31. Microstructure evolution of roll core during the preparation of composite roll by electroslag remelting cladding technology
  32. Improvement of toughness and hardness in BR1500HS steel by ultrafine martensite
  33. Influence mechanism of pulse frequency on the corrosion resistance of Cu–Zn binary alloy
  34. An interpretation on the thermodynamic properties of liquid Pb–Te alloys
  35. Dynamic continuous cooling transformation, microstructure and mechanical properties of medium-carbon carbide-free bainitic steel
  36. Influence of electrode tip diameter on metallurgical and mechanical aspects of spot welded duplex stainless steel
  37. Effect of multi-pass deformation on microstructure evolution of spark plasma sintered TC4 titanium alloy
  38. Corrosion behaviors of 316 stainless steel and Inconel 625 alloy in chloride molten salts for solar energy storage
  39. Determination of chromium valence state in the CaO–SiO2–FeO–MgO–CrOx system by X-ray photoelectron spectroscopy
  40. Electric discharge method of synthesis of carbon and metal–carbon nanomaterials
  41. Effect of high-frequency electromagnetic field on microstructure of mold flux
  42. Effect of hydrothermal coupling on energy evolution, damage, and microscopic characteristics of sandstone
  43. Effect of radiative heat loss on thermal diffusivity evaluated using normalized logarithmic method in laser flash technique
  44. Kinetics of iron removal from quartz under ultrasound-assisted leaching
  45. Oxidizability characterization of slag system on the thermodynamic model of superalloy desulfurization
  46. Influence of polyvinyl alcohol–glutaraldehyde on properties of thermal insulation pipe from blast furnace slag fiber
  47. Evolution of nonmetallic inclusions in pipeline steel during LF and VD refining process
  48. Development and experimental research of a low-thermal asphalt material for grouting leakage blocking
  49. A downscaling cold model for solid flow behaviour in a top gas recycling-oxygen blast furnace
  50. Microstructure evolution of TC4 powder by spark plasma sintering after hot deformation
  51. The effect of M (M = Ce, Zr, Ce–Zr) on rolling microstructure and mechanical properties of FH40
  52. Phase evolution and oxidation characteristics of the Nd–Fe–B and Ce–Fe–B magnet scrap powder during the roasting process
  53. Assessment of impact mechanical behaviors of rock-like materials heated at 1,000°C
  54. Effects of solution and aging treatment parameters on the microstructure evolution of Ti–10V–2Fe–3Al alloy
  55. Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel
  56. Dephosphorization of hot metal using rare earth oxide-containing slags
  57. Kinetic analysis of CO2 gasification of biochar and anthracite based on integral isoconversional nonlinear method
  58. Optimization of heat treatment of glass-ceramics made from blast furnace slag
  59. Study on microstructure and mechanical properties of P92 steel after high-temperature long-term aging at 650°C
  60. Effects of rotational speed on the Al0.3CoCrCu0.3FeNi high-entropy alloy by friction stir welding
  61. The investigation on the middle period dephosphorization in 70t converter
  62. Effect of cerium on the initiation of pitting corrosion of 444-type heat-resistant ferritic stainless steel
  63. Effects of quenching and partitioning (Q&P) technology on microstructure and mechanical properties of VC particulate reinforced wear-resistant alloy
  64. Study on the erosion of Mo/ZrO2 alloys in glass melting process
  65. Effect of Nb addition on the solidification structure of Fe–Mn–C–Al twin-induced plasticity steel
  66. Damage accumulation and lifetime prediction of fiber-reinforced ceramic-matrix composites under thermomechanical fatigue loading
  67. Morphology evolution and quantitative analysis of β-MoO3 and α-MoO3
  68. Microstructure of metatitanic acid and its transformation to rutile titanium dioxide
  69. Numerical simulation of nickel-based alloys’ welding transient stress using various cooling techniques
  70. The local structure around Ge atoms in Ge-doped magnetite thin films
  71. Friction stir lap welding thin aluminum alloy sheets
  72. Review Article
  73. A review of end-point carbon prediction for BOF steelmaking process
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 10.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/htmp-2020-0001/html
Scroll to top button