Band 114, Heft 10-11

Fused filament fabrication is a promising additive manufacturing technology and an alternative to traditional processes for the fabrication of polymer and fiber-reinforced polymer composites. In this work, the effects of process parameters such as layer thickness, infill density, and infill pattern on the ageing and free vibration characteristics of three-dimensional printed composites were investigated. It was observed that the water absorption rate is higher in acrylonitrile butadiene styrene (ABS) printed specimens compared to carbon fiber reinforced acrylonitrile butadiene styrene (CF/ABS) specimens due to the effect of carbon fiber which acts as a strong hydrophobic material. The free vibration characteristic of the printed composite specimen is found as per American Society for Testing Materials standards. From the results, it is found that the 5 % addition of carbon fiber, hexagonal pattern, and 0.30 mm layer thickness show an increase in the vibration behaviour of the composites compared to the specimen printed without reinforcement. Experimental modal analysis was carried out on a cantilever beam-like sample and revealed that the addition of fiber has enhanced natural frequencies and damping ratio.

Additive manufacturing has emerged as a trending methodology for producing different simple to complex geometries in minimum lead time, which in turn gives better quality attributes when compared to conventional manufacturing procedures. Fabrication of polylactic acid-based porous scaffold prototypes by 3-dimensional printing has been extensively performed successfully by many researchers. The dimensional accuracy of the 3-dimensional printed part is a very crucial aspect of bone tissue engineering. Dimensional precision of 3-dimensional biomimetic scaffolds has been a response characteristic somehow less focused on by researchers, though it is essential as it acts as a stereotype for defect recuperation while consequently developing extracellular matrix and bone regeneration. The present paper fosters re-tuning the process parameters of a fused deposition modeling based 3-dimensional printer while considering the dimensional precision as a response parameter by the Taguchi optimization technique using a full factorial design L27 orthogonal array set of design of experiments. The crystallinity of the polylactic acid filament material was assessed using differential scanning calorimetry and X-ray diffraction. The thermal breakdown of filament material was investigated utilizing a thermogravimetric analyzer. According to Taguchi’s signal-to-noise ratios, the optimum values were 0.14 mm of layer thickness, 20 mm s −1 of printing speed, and 80 % of infill percentage. In order to justify the results, response surface methodology was employed. R -square values for Taguchi and the response surface models were 88.61 % and 68.71 %, respectively.

This work aims to fabricate the functionally graded Inconel 600 on stainless steel 304 block using the wire arc additive manufacturing process. The main goal of this study was to additively create a built block with Inconel 600 filler wire. Inconel 600 is a very interesting material because of its resistance to non-magnetic, corrosive media, stress corrosion cracking due to chlorine ions is non-existent, outstanding mechanical properties, good weldability and high strength under a variety of temperature conditions. Inconel 600 alloy was studied in this work utilizing metal inert gas based wire arc additive manufacturing. Torch travel speed 5 mm s −1 and current 140 A. The bottom, middle and top layers of the newly developed fabricated block were mechanically and metallurgically characterized. The microstructure and texture evolution were characterized by means of optical microscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy. Mechanical characterization was done using the Vickers hardness test and tensile testing. Results reveal that the wire arc additively manufactured top portion has a crystalline structure showing better strength and hardness. The average hardness value was found to be 197.97 HV, the average ultimate tensile strength obtained was 616.22 MPa for the fabricated component.

Surface quality is a key factor in determining the mechanical performance of metallic materials. In this study, the influence of surface roughness on quasi-static mode tensile and low fatigue behavior of electron beam melted (EBMed) Ti‐6Al‐4V was studied. The results showed that the microstructure of the EBMed Ti‐6Al‐4V is mainly composed of α and β phases. It was found that the yield strength of the as-polished EBMed sample was about 200 MPa higher than the original EBMed sample, and the fatigue life was three times that. The fatigue crack initiation and propagation were explored, and it was found that the fatigue life was reduced on account of the thermal stress concentration that was generated as a result of the solidification shrinkage and the local stress concentration.

The present work aims to model the three-dimensional heat transfer coupled with the material flow model of 7075-T6 aluminium alloy material using the three tool pin profiles, square, pentagon, and hexagon, in the friction stir welding process. The temperature rise and fluid flow behaviour from the top to the bottom of the tool were evaluated. Also, the strain rate and dynamic viscosity variation were found near the tool pin and shoulder region. The results showed that the frictional contact heat between the shoulder surface and workpiece was responsible for the maximum heat generation. The probe area was minimum in the square tool pin geometry, which results in high heat generation due to the maximum shoulder surface contact area with the workpiece model. Furthermore, the analytical formula for calculating the heat generation on the tool shoulder/workpiece interface and the tool pin/workpiece contact region were also evaluated. The numerical modelling of heat generation was evaluated by COMSOL Multiphysics V5.3a software.

The distortion of components printed by wire arc additive manufacturing (WAAM) due to repeated thermal cycles affects the build quality. The residual stress generated due to these thermal cycles can be predicted with the help of the finite element method. The temperature distribution and residual stresses in the WAAM component are predicted using a numerical model presented in this paper. Also, the effect of clamping position on the substrate is investigated. For this, two different clamping positions are compared with the unclamped state. The residual stress is minimum for the unclamped case and has maximum strain. The case where the substrate is clamped at the centre generates 77 % more tensile stress when compared with the corner clamped case.

The invention of additive manufacturing technology, such as laser powder bed fusion, was initiated by the aerospace industries’ growing need for lightweight alloy components with intricate geometries. However, widespread adoption of lightweight alloy components is limited by size restrictions. Currently, only relatively small and simple-shaped objects can be efficiently produced using lightweight alloys. Thus, this research aims to investigate the effect of welding speed on butt joint quality of laser powder bed fusioned AlSi10Mg parts welded using an Nd:YAG laser. Laser beam welding is a method for welding small parts manufactured by laser powder bed fusion together to build large-scale and complex-shaped objects. Using a 2 kW continuous wave solid-state Nd:YAG laser with three different weld scan speeds (150, 175, and 200 mm min −1 ), autogenous, single-pass, square butt joints were created from 3 mm thick plates. Crystal orientation mapping and fractography results showed that the laser beam welding scan speed significantly impacts plastic deformation and fracture behavior. A significant amount of grain refinement and an Si-particle morphology change was realized in the weld zone’s microstructure, attributed to the increase in weld scanning speed. The transverse tensile test demonstrates that increasing the weld scan speed from 150 to 200 mm min −1 leads to significant growth in the efficiency of the weld joint, from 70 % to 77 %, arising from grain refinement (13–8 µm). However, a significant decrease in ductility is observed with increasing scan speed. In addition, it was determined that pores have substantial effect on tensile strength and ductility.

Wire arc melting is considered one of the most efficient processes in additive manufacturing in terms of material printed to material consumed ratio. 304 stainless steel is one of the prominent stainless steels with superior corrosion resistance and mechanical properties. 304 stainless steel components were deposited by wire arc additive manufacturing, depositing subsequent layers in the same and perpendicular directions. Mechanical properties, microstructure, XRD and microtexture studies were done by EBSD have been done for both the conditions and compared. Mechanical properties were found to be similar for both the conditions whereas the microstructure and microtexture showed equiaxed grains for depositing in the same direction and columnar grains for deposition in the perpendicular direction.

CoCrFeMnNi high entropy alloy was prepared by selective laser melting as a function of processing parameters by adopting the single factor variable method. The influence of process parameters on the microstructure and mechanical properties was investigated in detail. The results show that the alloy maintained a single-phase fcc structure, the microstructure is anisotropic and shows the presence of a high density of dislocations accumulated and entangled inside the grains. The ductility has a significant influence on the level of porosity, which in turn depends on the process parameters. Especially with the variation of hatch spacing, the elongation at break differs by at most 20.9 %.

The surface and microstructural characteristics of 3D printed parts play a significant role under mechanical loading. The authors have explored the effect of laser energy densities on the surface morphology, microstructure and mechanical behaviour of 17-4 precipitation hardened stainless steel fabricated under the direct metal laser melting technique. The considered processing parameters were laser energy density and its technical parameters: laser power, layer thickness, hatch spacing and scanning speed. The mechanical and metallurgical properties of the as-printed samples appeared better than the wrought counterpart due to the higher densification level (99.74 %) induced by the rotating scanning strategy. X‐ray diffraction revealed the presence of both the martensitic α phase and austenitic γ phase in the as-printed sample. There is no significant anisotropy in the mechanical behaviour as the build direction has a random texture with a fine columnar grain structure. The high laser energy density with low layer thickness results in an excellent surface finish. The tensile strength (1180 MPa) and the elongation for the as-printed sample (45.0 %) were considerably more significant than that for the wrought sample (1160 MPa and 26.0 %), which is attributed to the combination of low and high-angle boundaries, as confirmed by the electron backscatter diffraction results.

Bone tissue is the second most affected organ in the human body after blood. Tissue engineering is the area whereby a scaffold is used to regenerate the lost bone. However, the scaffold’s effectiveness is primarily based on the material and the fabrication process. The patient-specific structures are affected because of the fabrication process used to fabricate the scaffold as per requirement. In this regard, rheology plays an important role in the fabrication of the patient-specific scaffold, and it is a study of the flow of ink. This primarily affects both the conventional as well as the non-conventional fabrication processes. In this paper, the scaffold and bone tissue engineering, the different fabrication processes, and the importance of the rheological characterization are presented. In addition to this, the rheological properties of the developed HA/β-TCP composite slurry are evaluated for the extrusion-based additive manufacturing process. The developed ink’s rheological properties show that the flow behavior index of about 0.0497 ± 0.009, minimum flow stress required to make the ink flow of about 51.076 Pa at a strain rate of 0.111 %, and shape retention upto 75 % after 175 s are obtained. Also, different orientations are 3D printed using the developed slurry.

Glass fiber-reinforced plastic (GFRP) structural profiles in the construction industry are a promising alternative to conventional building materials due to their high strength-to-weight ratio, high tensile strength, insulation properties, chemical resistance, fatigue properties, and lower maintenance cost. This study aims to evaluate the compression behaviour of semi-compact and slender glass fiber-reinforced plastic I-sections. Short, intermediate, and long columns of both slender and semi-compact I-sections were subjected to axial compression, and the experimental capacity was compared to available theoretical results. It was found that the experimental capacity of short, semi-compact, and long columns were 27 %, 49 %, and 40 % lower than the theoretical capacity of semi-compact I-sections. Short slender sections had an ultimate experimental capacity 55 % greater than the theoretical results. However, lower ultimate capacities were achieved for intermediate and long columns in the case of slender sections when compared to the theoretical capacity. Slender sections were prone to both global and local buckling, whereas semi-compact sections failed by global buckling alone. The study also concludes the need for proper section classification of glass fiber-reinforced plastic sections to consider buckling characteristics. The existing theoretical equations to estimate the load-carrying capacity was found to be overly conservative; hence it is necessary to conduct numerical and parametric studies to develop equations that are more in agreement with the experimental results.

This study uses desirability function analysis to optimize the process parameters namely layer thickness, fill pattern, fill density, and build orientation for fused deposition modelling on polyethylene terephthalate glycol material. The Taguchi-desirability function analysis is one of the optimization techniques for the multi-objective decision-making process. Taguchi L 9 orthogonal array is employed in the test trials during the fused deposition modelling process. The output responses measured are dimension error, ductility, and tensile strength. The goal of process parameter optimization is to attain the best of the trials for minimal dimension error and maximum tensile strength and ductility. The best feasible amalgamation of input variables is discovered for the investigated and assessed response features utilizing desirability function analysis. As per the results obtained from experiments, it is concluded that the optimal combination of parameters is layer thickness of 0.1 mm, build orientation of 0°, fill density of 90 % and hexa fill pattern. By following this combination, the error in the dimensions was slightly increased which needed to be reduced, but both tensile strength and ductility were increased which are more desirable characteristics.

The effect of robotic weaving motion on the crystallographic orientation, texture and mechanical properties of thin-walled nickel titanium shape memory alloy fabricated via wire arc additive manufacturing is studied. Crystallographic orientation analysis reveals that the weaving motion alters the epitaxial growth of grains, which reduces the fraction of (001) oriented grains but increased the fraction of (110) and (111) oriented grains. Moreover, the weaving motion increases the fraction of equiaxed grains and homogeneously distributes Ni 4 Ti 3 phases. These changes improve the hardness and strength of the build and also introduce isotropy in mechanical properties. Results of the study reveal that arc weaving strategy has a great potential in achieving near isotropic tensile characteristics and is beneficial in terms of tailoring texture in building nickel titanium thin-walled smart material structures.

Rapid tooling evolved from rapid prototyping is a novel method for developing prototype tooling rapidly using various additive manufacturing techniques. Traditional injection moulding is unsuitable for low-volume production because of the high initial cost. This study is focused on a rapid tooling approach for producing an injection mould insert for the low-volume production of plastic components. A plastic injection mould insert is designed, developed using composite aluminium filled epoxy with minute protruded features and tested on a vertical injection moulding machine as a rapid tool for low-volume production of plastic components. The composite aluminium filled epoxy (CAFE) mould insert is prepared using a wax master from silicon rubber mould prepared using a stereolithography master. Experiments are performed to determine the optimum mixing ratio of epoxy: aluminium powder for making the composite aluminium filled epoxy injection mould. The mould insert prepared was tested for the injection of polypropylene components on a vertical injection moulding machine and analyzed for dimensional accuracy. The analysis of dimensional accuracy and viability of minute features on the injected parts shows promising results for up to 30 injected parts. The injection of parts after 30 pieces resulted in increasing mould erosion and pitting, causing mould damage at the 36 th injection shot. The experimental finding supports the feasibility of using the composite aluminium filled epoxy injection mould for low-volume production of the parts; however, the surface finish is inferior. The life of the mould is expected to give better results with a higher surface finish. It is also exposed that using mould release agents improves the life of the composite aluminium-filled epoxy injection mould.

Motivated by the beneficial effects of friction stir processing (FSP) for microstructural grain refinement, equiaxed grain production, and minimizing metallurgical defects, additive bead (AB) produced by the gas metal arc welding-wire arc additive manufacturing (GMAW-WAAM) technique was subjected to FSP. This was because deposited additive bead often develops defects such as shrinkage, voids, solidification cracking, during liquid to solid transformation. In this study, a low carbon steel double pass additive bead with 32 % lateral overlap was fabricated by the GMAW-WAAM technique followed by hybridization through FSP in the overlapped region (OR). The peak temperature estimation during bead deposition and FSP on bead was done through modeling by using ABAQUS. The microstructural analysis was carried out by using optical microscopy, scanning electron microscopy, electron backscattered diffraction, and transmission electron microscopy. The microstructure of OR of deposited additive bead is dominated by a combination of ferrite and bainite while that of hybrid additive bead (HAB) is dominated by a combination of ferrite and martensite. Further, the analysis revealed the effects of FSP on the OR in the form of grain refinement from 5.56 µm to 3.50 µm and a decrease in the low angle grain boundaries from 35.4 % to 10.6 %. The continuous dynamic recrystallization is observed since the bainitic fraction in the overlapped region decreased along with an increase in the fraction of martensite in the friction stir processed zone. The kernel average misorientation is observed to decrease after FSP from 1.001 of AB to 0.608. The microhardness test reveals the decrease in the hardness after FSP.

Additive manufacturing has become a cutting-edge technique to produce biomaterials for various clinical applications. Recent investigations have shown their significance and highlighted their future requirements. Many additive manufacturing technologies are mostly related to manufacturing polyether ether ketone (PEEK) based implants. Among them, fused filament fabrication (FFF) or fused deposition modelling (FDM) is the preferred method. Specifically, FFF builds complex scaffolds for tissue engineering and customized implants, which are not achievable with traditional fabrication methods. PEEK is a rigid, tissue-compatible, lightweight polymer with good wear characteristics and a long implant life. In general, PEEK has many valuable properties and the potential to solve many medical problems, especially orthopaedic implantation. This paper provides a brief study that gives an overview of PEEK-based biomaterials for FFF-based orthopaedic procedures, materials evolution, recent advancements, and the current research progress is also addressed systematically.

The welding fixture greatly impacts the weld quality matrixes. In this work, the welding fixture for ultrasonic-assisted gas tungsten arc welding to reduce the hot cracking behaviour in weldments was designed using the finite element analysis approach. A three-level, five-factor central composite design-based response surface methodology analysis was followed to vary the dimensions of the fixture for the modal and harmonic analysis of the fixture using Ansys software. The optimum fixture dimensions to achieve maximum displacement amplitude and minimum von-Mises stress have been optimized using a genetic algorithm approach. The model predictions for maximum displacement amplitude and minimum von-Mises stress were compared to the experimental findings at optimal conditions. A strong consensus between the model prediction by genetic algorithm and experimental findings indicates the correctness of the developed model.

The post-processing treatment of isostatic compression with different temperatures is improved with the interlayer bonding of the polylactic acid (PLA) parts. This bonding enhanced the tensile strength, percentage of strain, and elastic modulus of post-processed PLA samples through the tensile test. Here, the tensile strength is improved by about 127 % compared to untreated PLA due to interlayer bonding and the compressive force with 140 °C. Compression and flexural tests are utilized to examine the post-processed parts’ compression and flexural strength. It significantly improves the compressive and flexural strength of the post-processed parts, increasing to about 55 % and 64.5 % compared with the untreated PLA parts. Additive manufacturing of PLA parts is significantly progressed in the 3D printing of biodegradable and eco-friendly components through a layer-by-layer deposition.

Over the years incremental sheet metal forming (ISMF) has developed as a futuristic technique in which the metal sheets are transformed into the final product with the use of a solid metallic rod having a designed end, rather than a dedicated die. The production lead time is quite high in this process as compared to the conventional sheet forming methods. ISMF is most suitable for developing model for the purpose of research and development, manufacturing of the customized part and for low-volume production. Tool life is an important criterion for determining feasibility of any manufacturing process. The sliding of the forming tool over the clamped metal worksheet during the ISMF is another important aspect for understanding the tool-wearing behaviour. The present study has investigated the wearing of the 440C grade steel forming tool during the ISMF of aluminum grade AA3003-O. It has examined the process statistically to establish that the step downsize ( P = 0.021) and sheet metal thickness ( P = 0.005) significantly influence the wearing of 440C steel tool. The coefficient of performance, i.e., R 2 has been reported as 92.0 % with an adjusted R 2 of 81.9 %.

Inconel 625 (IN 625) is widespread in the manufacturing of critical components such as nuclear reactors, control rods, steam turbines, supercritical boilers, rotary shafts, aerospace engines, etc., that operate in severe harsh environments. However, if the service environments consist of sulphur (fuel tanks), chlorine (supercritical boilers and heavy water plants), H 2 S, HCl, etc., this alloy will suffer from localized corrosion attacks that minimize its resistance towards corrosion, followed by sudden failure. This study is aimed to facilitate the anti-corrosion characteristics of IN 625 by cladding it with Colmonoy 5 (NiCrSiFeB) alloy particles. The clad microstructure was revealed by micrographs captured by means of optical and field emission scanning electron microscopy followed by the nanoindentation study to analyze the hardness offered. Corrosion testing was carried out on both IN 625 and Colmonoy 5 clad samples at various intervals (0, 13, 27 and 56 h) for interrogating the corrosion behavior in terms of Tafel and impedance plots along with the surface roughness examination using scanning probe microscopy. The results showed that the clad region consists of dendritic microstructure along with the segregation of interdendritic Cr-rich precipitates after solidification. These interdendritic precipitates aid in improving the hardness at the clad region. Moreover, the clad samples have better anti-corrosion characteristics because of the existence of dendritic and interdendritic phases compared to the IN 625 samples in terms of current density, polarization resistance and average surface roughness values.

Stainless steel (SS) 410 is widely used in many engineering applications such as turbines, nuclear reactor components and seamless pipes due to its superior mechanical properties i.e., high mechanical strength, creep resistance and ductility. Corrosion resistance is an important property which is required for these components to reduce the material degradation from the surface. In the present study, an investigation has been made to enhance the electrochemical behavior of SS410 by depositing SS420 particles using the laser cladding technique. The hardness measured through nano-indentation tests and microstructure of the resulting surface were analysed. Also, electrochemical studies were performed on laser clad specimens with different durations such as 0 h, 8 h, 14 h and 36 h. The improvements in corrosion resistance were analysed using polarization curves and electrochemical impedance spectroscopy (EIS). Further, the morphology and roughness of the corroded surface were analysed. The results showed that a closely packed acicular structure was formed through cladding, which improved the nanohardness compared to the base material. In addition, the clad specimen with 14 h test duration exhibited excellent corrosion resistance amongst the other specimens. The morphological analysis of the corroded specimen revealed the formation of oxides which is indentified to be a major reason for improved corrosion resistance.