Microstructure and mechanical properties of keyhole repair welds in AA 7075-T651 using refill friction stir spot welding

被引：86

作者：

Reimann, Martin ^{[1
]}

Goebel, Jannik ^{[1
]}

dos Santos, Jorge F. ^{[1
]}

机构：

[1] Helmholtz Zentrum Geesthacht, Inst Mat Res, Solid State Joining Proc Dept, Mat Mech, Max Planck Str 1, D-21502 Geesthacht, Germany

来源：

MATERIALS & DESIGN | 2017年 / 132卷

关键词：

Friction spot welding; Keyhole closure; Termination hole; FSW exit hole; Repair weld; ALUMINUM-ALLOY JOINTS; PARAMETERS; BIT;

D O I：

10.1016/j.matdes.2017.07.013

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

To develop a suitable keyhole closure process in high-strength AlZnMg(Cu) alloys, refill friction stir spot welding was used to perform repair welds of through holes of 7.5 mm diameter in AA 7075-T651 plateswith 6 mm thickness. The thermal cycle and the evolution ofmicrostructural features were investigated in detail. The mechanical performance of the welds was studied based on the changes in microstructure and temperature exposure caused by the welding process. Thermal cycle measurements revealed high heating rates and peak temperatures of up to 540 degrees C in the weld center. Leftover grains from the base metal that did not recrystallize were determined in the stirred zone of the weld center. The welds showed a W-shaped hardness distribution with a lowest hardness of 70% of base metal values in the heat affected zone. Under quasi-static loading, two failure modes were determined, with mode 1 failure occurring in the heat affected zone and mode 2 failure occurring in the outer regions of the stirred zone with crack initiation in the lower portions of the weld. Post-weld natural aging was proven to be highly significant for the mechanical properties of the welds and is effective for up to 4 weeks after welding. (C) 2017 Elsevier Ltd. All rights reserved.

引用

页码：283 / 294

页数：12

共 23 条

[1] Filling exit holes of friction stir welding lap joints using consumable pin tools [J].