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用光学金相及扫描电镜分析方法研究了20Cr2Ni4A钢的低温回火脆性机理.研究结果表明,该钢在250～350℃区间回火时出现低温回火脆性,其原因与碳化物沿奥氏体-马氏体相界面析出及杂质元素偏聚于原奥氏体晶界有关,后者易导致沿晶断裂.提出了适宜的低温回火温度范围.
The mechanism of low-temperature tempering brittleness of 20Cr2Ni4A steel was studied by optical metallography and scanning electron microscopy.The results show that the low temperature temper brittleness occurs when the steel is tempered in the range of 250 ~ 350 ℃, the reason is that the carbide along the austenite - martensitic interface precipitation and segregation of impurity elements in the original austenite grain boundaries, the latter easily lead to intergranular fracture.A suitable temperature tempering temperature range is proposed.