Characterization of the Heat Affected Zone in Gas Tungsten Arc Welds of Unalloyed Austempered Ductile Iron

Ahmet Karaaslan; Cem Akca

doi:10.3139/120.100883

Article

Characterization of the Heat Affected Zone in Gas Tungsten Arc Welds of Unalloyed Austempered Ductile Iron

Ahmet Karaaslan and Cem Akca

Published/Copyright: May 28, 2013

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From the journal Materials Testing Volume 50 Issue 5

Abstract

Austempered ductile iron (ADI) exhibits a wide range of mechanical properties depending on the austempering conditions. It is thus extremely important to evaluate the different characteristics of ADI welds where joining is inevitable. In this study, unalloyed ferritic-pearlitic ductile iron specimens which contain 3.69% C, 2.47% Si and 0.2% Mn were austempered in different temperatures to obtain an upper and lower bainitic microstructure and then welded using Gas Tungsten Arc Welding (GTAW) without filler. The results showed that the lower and upper bainitic ADIs can be welded successfully without any crack formation in the heat affected zone (HAZ). It was also observed that the HAZ of the specimen which have been austempered at 275°C for 60 min exhibit a higher hardness than that austempered at 375°C. As the critical austempering time for a homogeneous HAZ characteristic 100 min has been identified.

Kurzfassung

Ausgetempertes duktiles Eisen (ADI) deckt einen großen Bereich von Werkstoffeigenschaften abhängig von der Austemperungstemperatur ab. Es ist daher besonders wichtig, die Charakteristika der Schweißverbindungen von ADIs zu kennen. In der zugrunde liegenden Studie wurden unlegierte ferritisch-perlitische Eisenproben mit 3,69% Kohlenstoff, 2,47% Silizium und 0,2% Mangan bei verschiedenen Temperaturen ausgetempert, um eine obere und untere Zwischenstufe zu erhalten, und danach mit dem Wolfram Inert Gas-Verfahren ohne Zusatzwerkstoff geschweißt. Die Ergebnisse zeigen, dass die unteren und oberen bainitischen ADIs erfolgreich geschweißt werden können, ohne dass Risse in der Wärmeeinflusszone (WEZ) auftreten. Es wurde auch beobachtet, dass die WEZ in den Proben, die bei 275°C über 60 min ausgetempert wurden, eine höhere Härte aufweist als in denjenigen, die bei 375°C ausgetempert wurden. Als kritische Austemperungszeit für die Ausbildung einer homogenen WEZ wurden 100 min bestimmt.

Dipl.-Ing. Dr. mont. Ahmet Karaaslan, born 1968, studied Metallurgy and Materials Engineering at the Technical University Yildiz in Istanbul, Turkey, and achieved his PhD in 1999 at the Instiute for Metals Science and Materials Testing at the Montanuniversity Leoben in Austria. Since 1999 he is in the section Materials Engineering at the Technical University Yildiz, Turkey.

Dr. Cem Akca, born in 1978, graduated from the Yildiz Technical University (YTU), Department of Metallurgical Engineering in 1999. He had his M.Sc. and Ph.D. degrees from YTU Department of Metallurgical and Materials Engineering in 2002 and 2006 respectively. He has been working in YTU Dept. of Metallurgical and Materials Eng. on casting and solidification since 1999.

References

1 E.Dorazil: Mechanical Properties of Austempered Ductile Iron, Foundry Management & Technology (1986), pp. 36–45.Search in Google Scholar

2 D. Q.Sun, X. Y.Gu, W. H.Liu, Z. Z.Xuan: Welding consumable research for austempered ductile iron (ADI), Materials Science and Engineering A402 (2005), pp. 9–1510.1016/j.msea.2005.01.034Search in Google Scholar

3 K. L.Hayrynan, K. R.Brandenberg, J. R.Keough: Applications of austempered cast irons, AFS Transactions02–084 (2002), pp. 1–10Search in Google Scholar

4 E.Olivera, R.Dragan, Z.Slavica, S.Leposava, T. J.Milan: Microstructure and fracture of alloyed austempered ductile iron, Materials Characterization57 (2006), pp. 211–21710.1016/j.matchar.2006.01.014Search in Google Scholar

5 T. N.Rouns, K. B.Rundman, D. M.Moore: On the structure and properties of austempered ductile cast iron, AFS Transactions90 (1985), pp. 815–840Search in Google Scholar

6 Z.Lawrynowicz: Transition from upper to lower bainite in Fe–C–Cr steel, Materials Science and Technology, 20 (2004), No. 11, pp. 1447–145410.1179/026708304X3953Search in Google Scholar

7 M.Bahmani, R.Elliot, N.Varahram: Austempered ductile iron: A competitative alternative for forged induction-hardened steel crankshafts, International Journal of Cast Metals Research (1997), No. 9, 249–257Search in Google Scholar

8 K. B.Rundman, W. J.Dubensky: An electron microscope study the carbide formation in austempered ductile iron, AFS Transactions, 93 (1985), pp. 389–394Search in Google Scholar

Published Online: 2013-05-28

Published in Print: 2008-05-01

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https://doi.org/10.3139/120.100883