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Accessible Unlicensed Requires Authentication Published by De Gruyter January 18, 2019

Strain accumulation at the top and bottom side of a friction stir welded alloy AZ31 under tensile and compressive loading

Dehnungsakkumulation auf der Ober- und Unterseite vor Rührreibschweißungen einer Legierung AZ 31 unter Zug- und Druckbeanspruchung
Dejia Liu, Rui Guo, Yanchuan Tang, Yong Hu and Longzhi Zhao
From the journal Materials Testing

Abstract

Strain accumulation is easily formed in friction stir welded Mg alloys which significantly deteriorate the strength of the joints. However, the formation mechanisms of strain accumulation are not well understood. The present study aims to explore the different strain accumulations on the top and bottom side of welded samples using tensile and compressive tests. An effective procedure is provided for measuring strain accumulation. An interesting finding is that the measured strain accumulations differ from those determined by visual inspection. The analyses indicate that the different types of strain accumulation at both sides have a close relationship with the shear layers and textural variations in the stir zone. Additionally, a model for the formation of strain accumulation at the top and bottom side of the Mg weld joints is provided.

Kurzfassung

In rührreibgeschweißten Magnesiumlegierungen können sich leicht Dehnungsakkumulationen ausbilden, die die Festigkeit der Verbindung erheblich herabsetzen. Die Bildungsmechanismen der Dehnungsakkumulationen sind noch nicht gut verstanden. Die diesem Beitrag zugrunde liegende Studie zielt daher darauf ab, die verschiedenen Dehnungsakkumulationen auf der Ober- und der Unterseite von geschweißten Proben mittels Druck- und Zugversuchen zu untersuchen. Hierzu wird eine effektive Prozedur vorgestellt, um die Dehnungsakkumulationen zu messen. Ein interessantes Ergebnis ist es, dass diese gemessenen Dehnungsakkumulationen von denen einer Sichtprüfung abweichen. Die Analysen deuten an, dass die verschiedenen Dehnungsakkumulationen auf beiden Seiten in einem engen Zusammenhang mit Scherbändern und Texturvariationen in der rührreibgeschweißten Zone stehen. Zusätzlich wird ein Modell für die Bildung der Dehnungsakkumulationen auf der Ober- und Unterseite der Mg-Schweißverbindungen vorgestellt.


*Correspondence Address, Dr. Dejia Liu, School of Materials Science and Engineering, East China Jiaotong University, Shuang Gang Dong Jie 808#, Economic and Technological Development Zone, Nanchang, P. R. China, E-mail:

Dr. Dejia Liu, born in 1982, is a head of materials forming and control engineering at East China Jiaotong University, Nanchang, P. R. China. He graduated from Chongqing University in 2014 with a degree in Materials Science and Engineering and received a Ph.D. His main research interests are friction stir welding and processing of magnesium alloys, as well as the surface modification by laser cladding.

Dr. Yanchuan Tang, born in 1989, graduated from the University of Science and Technology Beijing, China in 2017 with a degree in Materials Science and Engineering and received his PhD. Currently, he is a lecturer at the School of Materials Science and Engineering, East China Jiaotong University in Nanchang. His main research interest is the strengthening and toughening mechanisms of materials.

Dr. Yong Hu, born in 1982, graduated from Nanchang University in 2009 with a degree in Material Processing Engineering and received a Ph.D. Currently he is an associate professor at the School of Materials Science and Engineering, East China Jiaotong University. His main research interest is new material processing technologies.

Dr. Longzhi Zhao, born in 1977, graduated from the Institute of Metal Research Chinese Academy of Sciences, Shenyang, P. R. China in 2006 with a degree in Material Processing Engineering and received a Ph.D. Currently, he is a deputy dean of the School of Materials Science and Engineering, East China Jiaotong University, Nanchang, P. R. China. His main research interest is the strengthening mechanisms for new materials in laser cladding.


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Published Online: 2019-01-18
Published in Print: 2018-12-04

© 2018, Carl Hanser Verlag, München