7050铝合金型材开裂成因分析

Crack cause analysis of 7050 aluminum alloy profile

采用体视镜、光学显微镜、扫描电镜等观察了7050铝合金型材裂纹的断口形貌、显微组织;借助光谱仪和能谱仪分析了合金的化学成分和裂纹处的微区成分。结果表明,合金裂纹位于型材筋条端部粗晶区域,裂纹沿粗晶晶界开裂。造成合金型材开裂的原因是固溶淬火时产生的淬火应力超过了合金型材粗晶区的强度所致。合金型材裂纹为淬火裂纹。

The fracture morphology and microstructure of 7050 aluminum alloy profiles were observed by using stereo microscope,optical microscope and scanning electron microscope.The chemical composition of the alloy and the microzone composition at the crack site were analyzed by spectrometer and EDS.The results show that the alloy crack was located in the coarser grain region at the end of the bar and along the grain boundary of coarser grain.The causes of cracking of alloy profiles are as follows:quenching stress produced during solution quenching exceeds the strength of coarse grain area of alloy profiles and leads to cracking;The cracks of alloy profiles are quenching cracks.