Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

Guowei Li; Furong Chen; Yongquan Han; Yahong Liang

doi:10.3390/ma11030379

Improving Mechanical Properties of PVPPA Welded Joints of 7075 Aluminum Alloy by PWHT

Materials (Basel). 2018 Mar 5;11(3):379. doi: 10.3390/ma11030379.

Authors

Guowei Li¹, Furong Chen², Yongquan Han³, Yahong Liang⁴

Affiliations

¹ School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China. liguowei-2008@imut.edu.cn.
² School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China. cfr7075@imut.edu.cn.
³ School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China. hyq@imut.edu.cn.
⁴ School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010051, China. liangyahong@imut.edu.cn.

Abstract

In this study, 7075 aluminum alloy with a thickness of 10 mm was successfully welded with no obvious defects by pulsed variable polarity plasma arc (PVPPA) welding. The mechanical properties of PVPPA welded joints have been researched by post weld heat treatment (PWHT). The results indicate that the heat treatment strongly affects the mechanical properties of the welded joints. The tensile strength and the microhardness of the welded joints gradually improved with the increase of the solution temperature. With the increase of the solution time, the tensile strength, and microhardness first dramatically increased and then decreased slightly. The best tensile strength of 537.5 MPa and the microhardness of 143.7 HV were obtained after 490 °C × 80 min + 120 °C × 24 h, and the strength was nearly 91.2% of that of the parent metal, and increased about 35% compared with as-welded. The improvement of strength and microhardness was mainly due to the precipitation of η' phase.

Keywords: 7075 aluminum alloy; PVPPA welding; heat treatment; mechanical properties; microstructure.