The knowledge on the properties of used materials is urgently needed for reasonable life - prediction and life - distribution . as cylinder bolts are concerned , they often rapture at the first tooth - root resulting from lower high temperature strength of their material and higher stress . since bolts operate at high temperature environment , creep skew and damage causing their failure are important factors that can not been neglected 就汽缸螺栓而言，由于螺栓材料的高温强度偏低，预紧力过大，常常在螺栓的第一齿根部位发生蠕变脆性断裂，因其长期在高温环境下工作，蠕变变形和蠕变损伤是其失效的一个不可忽略的重要因素。
