上夹板断裂原因分析

某材料牌号为30CrMnSiNi2A的上夹板进行强度试验,当加载到220 kN时在夹板截面突变处R根部发生突然断裂,其设计要求是在加载到300 kN时不允许破坏。通过断口宏微观观察、化学成分分析、金相组织检查、硬度测试等手段对夹板的断裂原因进行了分析。结果表明:夹板金相组织为正常的回火马氏体,无过热过烧的粗大组织,该上夹板断裂失效原因是氢脆所致;对于高强度钢,即使氢含量较低,也会在应力集中处发生氢致脆性断裂。

Fracture Analysis of Upper Batten

An upper batten made of 30CrMnSiNi2A steel fractured suddenly at the toot of Rtransition under the load of 220 kN during tensile test. The fracture load is above 300 kN according to the design requirement. In order to find the failure cause, chemical composition analysis, microstructure examination, hardness testing and fracture observation were carried out. The results show that the fracture mode of the upper batten was hydrogen induced brittle fracture. The microstructure of the upper batten is normal. To high-strength steel, hydrogen induced brittle fracture may take place at the stress concentration zone even if the content of the hydrogen is not very high. Based on the analysis results, the failure reason is sugguested to be hydrugen embrittlement.