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一、前言压力容器和高压管道的部件承受较大的周期应力,常发生低周期疲劳断裂。这是由于构件承受的工作应力超过材料的屈服强度,因而在每一个应力循环中产生较大的塑性变形。循环塑性变形成为低周期疲劳断口的主要原因,部件的疲劳寿命一般在10~2～10~5循环周期之间。这种断口的形成与高周期疲劳断口相比,有许多不同之处,须要进一步探讨。本文通过扫描电镜对45号钢在不同的应力状态和不同的热处理条件下产生的各种疲劳断
I. INTRODUCTION Parts of pressure vessels and high-pressure pipes are subject to large cyclic stresses and often cause low-cycle fatigue fracture. This is due to the components of the work stress to withstand the yield strength of the material, resulting in each stress cycle greater plastic deformation. Cyclic plastic deformation as the main reason for low cycle fatigue fracture, the fatigue life of parts is generally between 10 ~ 2 ~ 10 ~ 5 cycles. Compared with the high-cycle fatigue fracture, there are many differences between the formation of such fracture and need to be further explored. In this paper, scanning electron microscopy of 45 steel in different stress conditions and different heat treatment conditions produce a variety of fatigue off