球形封头热冲压成形残余应力分析

Residual stress analysis of hot stamping for spherical head

球形封头在其直边段易发生折皱和开裂,残余应力过大是造成其缺陷的根本原因之一。针对无损X射线衍射法、有损全释放法这两种残余应力测试方法的检测原理、测试方法及应用特点等方面进行了分析介绍。以12Cr2Mo1R(H)材料为例,采用两种方法分别测量了球形封头热冲压成形后的外壁残余应力值。揭示了封头外壁残余应力分布规律:封头外壁的残余应力值由底部开始逐渐增大,过渡段为应力值转折区域,进入直边段后,残余应力值达到最大。通过对比发现:两种测量方法测得的残余应力变化规律相似;全释放法测得的残余应力值较大;残余应力值在封头外壁直边段部分达到最大。

Wrinkling and cracking easily happen in the straight part of spherical head, and one of the essential reasons is the excessive residual stress. It was introduced and analyzed the principle, procedure and application characteristics of undamaged X - ray diffraction method and damaged full release method. For material 12Cr2MolR （H） , the outer wall residual stress after hot stamping for spherical head was studied by the above methods. The residual stress distribution rule of outer wall of head was revealed ： the residual stress values of head outer wall increased gradually from the bottom. The transition section was the transition area of stress value. After entering straight section, the residual stress reached the maximum value. The results show that the residual stress changing rules are the same by two meth- ods of measurement, the residual stress values by full release method are bigger, the residual stress values achieve the maximum value in the straight section of the head outer wall.