摘要
对42 mm厚的A7N01S-T5铝合金板双面搅拌摩擦焊接头进行了组织分析、硬度测试。将接头分为上、中、下三层分别进行高频疲劳试验,通过S-N曲线、断口分析对接头疲劳性能进行研究。结果表明,焊核区微观组织为细小的等轴晶,热影响区组织相对母材有所粗化,前进侧热机影响区组织表现为高度扭曲变形,后退侧组织无明显变形;接头横截面中线的显微硬度分布呈"W"型,焊核区硬度相对母材有所下降,约为母材硬度的88%。距离焊缝中心约25 mm处的软化区硬度最低,约为母材硬度的72%;接头上、中、下三层疲劳极限相近,疲劳试样大多断裂于热影响区软化区,而"S"线缺陷的存在并未引发疲劳源。
The microstructure analysis and hardness test of double-side friction stir welding joint of A7N01S-T5 aluminum alloy plates with thickness of 42 mm were carded out. The welded joint was divided into the upper, middle and lower layers for the high frequency fatigue test. The fatigue properties Of welded joints were studied by the analysis of S-N curves and fracture. The results show that microstmcture of the weld nugget zone is free, equiaxed grains and the microstmcture of the heat affected zone is coarser than that of base metal. The microstmcture of the advanced side TMAZ shows high distortion, while the microstmcture of the retreating side TMAZ has no obvious deformation. The micro-hardness distribution at center line in cross section of the welded joint shows ＂W＇ type. Compared with the base metal, the micro-hardness of the weld nugget zone decreases, which is about 88% of base metal＇s micro-hardness. The micro-hardness of the softening zone about 25 mm distance from the weld center is the lowest, which is about 72% of base metal＇s micro-hardness. The fatigue limits of upper, middle and lower layers of welded joint are similar. The fracture of fatigue specimens mostly occurrs in the softening zone, while the existence of the ＇S＇ line defect does not induce the generation of fatigue source.
出处
《热加工工艺》
CSCD
北大核心
2017年第19期44-47,共4页
Hot Working Technology
