装配间隙对6005A-T6铝合金型材BT-FSW接头抗应力腐蚀性能的影响

Influence of Assemble Gap on Stress Corrosion Resistance of BT-FSW Joints of 6005A-T6 Aluminium Profile

对6005A-T6铝合金型材进行BT-FSW双轴肩搅拌摩擦焊,研究了0、0.5和1 mm三种装配间隙对焊接接头应力腐蚀(SCC)敏感性的影响。利用SEM扫描电镜对接头慢拉伸(SSRT)应力腐蚀试件断口截面形貌和微观缺陷进行了观察与分析。结果表明:装配间隙越大,焊接接头应力腐蚀开裂敏感性就越大。在0~0.5 mm范围内,间隙量对接头中心区域组织形貌影响较弱,断口均位于热影响区HAZ,是典型韧性断口。当间隙量到达1 mm时,应力腐蚀裂纹萌生于焊核区中心C型线界面,腐蚀区光亮平坦,中心放大区可以观察到细小放射状河流花样,断口类型为沿晶脆性断裂。

BT-FSW of 6005 A-T6 aluminum alloy profiles was carried out, the influence of three assembly gaps(0 mm,0.5 mm and 1 mm) on the stress corrosion cracking(SCC) sensitivity of welded joints was studied. The fracture morphology and micro-defects of the SSRT stress corrosion specimen of the joint were observed and analyzed by means of SEM. The results show that the bigger the assembly gap is, the bigger the stress corrosion cracking sensitivity of the welded joint is. Within the range of 0-0.5 mm, the gap has little influence on the microstructure morphology of the central region of the joint, the fractures are all located in heat affected zone and they are typical ductile fracture. When the assembly gap reaches 1 mm, the stress corrosion crack initiates on the interface of the C-line in the center of the nugget zone. The corrosive area is bright and flat, fine radial river patterns can be observed in the central enlargement area. The fracture type is intergranular brittle fracture.