An Investigation of TIG Welding of AZ31 Magnesium Alloy Sheets*

Bilge Demir; Ahmet Durgutlu

doi:10.3139/120.110635

Article

An Investigation of TIG Welding of AZ31 Magnesium Alloy Sheets*

Bilge Demir and Ahmet Durgutlu

Published/Copyright: October 11, 2014

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From the journal Materials Testing Volume 56 Issue 10

Abstract

In this study, butt welding of commercial AZ31 magnesium alloy sheets has been investigated by using the tungsten inert gas welding process with alternating and pulsed current. Magnesium alloy welding, although well developed and understood, can present some problems, such as porosity, hot cracking, oxide formation, etc. Samples of the welded parts have been examined by optic microscopy and mechanic tests. Results showed that porosities and homogeneous micro size oxides were rarely found. Orientation of the weld microstructure in direction of the heat transfer were also rarely observed and equiaxed grain morphology was the dominant grain structure as in the base metals. In addition, fusion zone and HAZ of the welded samples have generally shown twins. This seems to be a very dominant grain type particularly in pulsed samples. Hot cracking was not observed in any samples. Results of mechanical tests showed that pulsed current seems to generate more favorable higher mechanical properties of weld joints than alternating current for magnesium alloys.

Kurzfassung

In dieser Studie wurde das Stumpfschweißen von Blechen aus der kommerziellen Magnesiumlegierung AZ31 mit dem Wolfram-Inertgas-Schweißverfahren mit Wechsel- und Impulsstrom untersucht. Das Schweißen von Magnesiumlegierungen, obwohl gut entwickelt und verstanden, könnte hinsichtlich Porosität, Heißrissbildung, Oxidbildung usw. problematisch sein. Schweißproben wurden lichtmikroskopisch und anhand mechanischer Tests untersucht. Ergebnisse zeigten, dass Porositäten und homogene Feinstoxide selten auftraten. Orientierungen des Schweißgefüges in Richtung der Wärmeübertragung wurde auch nur selten beobachtet. Äquiaxiale Kornmorphologie dominierte, ebenso wie im Grundwerkstoff. Darüber hinaus finden sich in der Schmelzzone und WEZ der geschweißten Proben generell Zwillinge. Dies scheint ein sehr dominanter Korntyp besonders in gepulsten Proben zu sein. Heißrissbildung wurde an keiner Probe beobachtet. Mechanische Tests zeigten für Magnesiumlegierungen, dass mit gepulsten Strömen scheinbar bessere mechanische Eigenschaften der Schweißverbindung erzielt werden als mit Wechselstrom.

**Correspondence Address Bilge Demir, Manufacturing Engineering Department, Technology Faculty, Karabuk University, Demircelik kampusu, 78100 Karabuk, Turkey, E-mail: bdemir@karabuk.edu.tr

Dr. Bilge Demir was born in Pazar/Tokat in Turkey. In 1993, he graduated from the Department of Metal Education at Gazi University in Ankara, Turkey, and then started his academic career at that university. In 1995, he began working as a research assistant. He received his Master of Science degree in 1997 and graduated with a PhD in 2003. He became Associated Professor in 2010 and now works in this position at Karabuk University, Turkey. His research areas are welding, microstructural and mechanical properties as well as forming and formability.

Dr. Ahmet Durgutlu was born in Bilecik in Turkey. He graduated from the Department of Metal Education at Gazi University in Ankara, Turkey, in 1993 and then began his academic career at that university in 1994, working as a research assistant. He acquired his Master of Science degree in 1997and his PhD in 2003. He became Associated Professor in 2012 and now holds this position at Gazi University. His research areas are welding technology, metallurgy as well as mechanical properties of welded joints.

Presented during the 3^rd International Conference on Welding Technologies and Exhibition (ICWET'14) in Manisa, Turkey

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Published Online: 2014-10-11

Published in Print: 2014-10-01

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