摘要
采用TIG焊对2A12铝合金薄板进行焊接,并对接头的组织及力学性能相关性进行分析.金相观察发现焊缝及熔合区内晶粒粗大且不均匀,焊缝从边缘的柱状晶向中心的等轴晶过渡,熔合线附近出现粗细晶混杂分布.采用显微硬度及拉伸试验研究了焊接接头力学性能不均匀性.结果表明,硬度最小值处于焊缝的熔合区,拉伸试样亦断裂在该区,与组织分布相对应;对断口进行扫描电镜观察,采用电子探针对二次相进行成分分析.引起2A12铝合金焊接接头性能下降的主要原因是焊缝在冷却过程中由于偏析而生成的低熔点共晶θ相和S相.
TIG welding has been carried out for thin plate of aluminium alloy 2A12,and the correlation between microstructure and mechanical properties was analyzed.Coarse and mixed grains were observed in welding area by means of metallographical analysis.From the edge to the center of welding seam,the volume grains changed to isometric grains,a mixed grain distribution was shown near the fusion line.Inhomogeneous mechanical behavior was studied by micro hardness and tensile testing.The results showed that minimal hardness was located in the fusion line,and fracture was also happened in the same area,which was accordance to the microstructure distribution.SEM and electron probe tests were done for fracture analysis and elements identification of welded joints,it was shown that the main reason for strength decreasing of aluminium alloy welded joint was the precipitation phases θ and s,which were generated during cooling process of welding.
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2011年第9期5-8,113,共4页
Transactions of The China Welding Institution
基金
国家自然科学基金资助项目(51065016)
甘肃省留学人员科技资助项目(1001ZBS113)
关键词
焊接接头
微观组织
力学性能
低熔点共晶
welding point
microstructure
mechanical properties
eutectic point
