6016铝合金包边开裂组织性能研究

针对6016铝合金板材在实际生产中出现的包边开裂问题,采用金相显微镜、扫描电镜对包边开裂过程中的组织演变进行了分析,探究了包边产生开裂的原因。结果表明:在未变形区域,晶粒均为再结晶晶粒,其中,表面晶粒分布较为均匀,横、纵截面表层晶粒尺寸较心部晶粒大,且存在异常长大的晶粒,对包边性能会产生不利的影响;在包边开裂处,外拉伸面和内部压缩处萌生裂纹,且还存在粗滑移带,这主要是由局部化高应变导致的,微裂纹的存在是晶界脱粘的结果;在裂纹表面发现大量的韧窝,裂纹处存在粗大的第二相,经能谱分析为富铁相,裂纹的形成和扩展与富铁相有关,细化富铁相有利于提高包边性能。

Study on microstructure and properties for 6016 aluminum alloy hemming crack

For the hemming crack problem of 6016 aluminum alloy sheet in the actual production,the reasons for the hemming crack were explored,and the structure evolution in the process of hemming crack was analyzed by metallographic microscope and scanning electron microscope. The results show that in the undeformed area,the grains are all recrystallized grains,and the grain distribution on the surface is relatively uniform,the grain size in the surface layer of cross and longitudinal sections is larger than that in the core,and there are abnormally grown grains to adversely affect the hemming performance. At the hemming cracks,the cracks are initiated at the outer tensile surface and the inner compression area,there are also coarse slip zones in the area mainly caused by the localized high strain,and the existence of microcracks is the result of grain boundary debonding. Furthermore,a large number of dimples are found on the surface of cracks,and there is a coarse second phase at the cracks which is the iron-rich phase by the energy spectrum analysis. Since the formation and propagation of cracks are related to the iron-rich phase,refining the iron-rich phase is beneficial to improve the hemming performance.