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本文用示波冲击法研究了30CrMnSiA钢的高温回火脆性,并对冲击试样进行了宏观断口形貌观察。韧性状态下这种钢的示波冲击曲线可区分为弹性变形功、塑性变形功和裂纹稳定扩展功及失稳扩展功四个部分。这时的宏观冲击断口由萌生区、稳定扩展区和失稳扩展区三部分组成。出现回火脆性时,示波冲击曲线上稳定扩展功变为零,而失稳扩展功严重下降;宏观断口上稳定扩展区消失。因此,用裂纹扩展功的变化能更好地反映回火脆性的程度。
In this paper, the high temperature temper brittleness of 30CrMnSiA steel was studied by oscillometric method, and the macroscopic fracture morphology of impact specimen was observed. The ductile state of this steel oscillometric impact curve can be divided into elastic deformation work, plastic deformation work and crack stability expansion work and instability expansion work of four parts. At this time, the macroscopic impact fracture consists of three parts: the sprouting area, the stable extension area and the instability extension area. When temper embrittlement occurs, the steady expansion work on the oscillometric impact curve becomes zero, but the steady-state expansion work decreases seriously; the stable extension area disappears on the macro fracture. Therefore, the variation of crack propagation work better reflects the degree of temper embrittlement.