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采用扫描电镜、金相显微镜和XRD等手段研究了5Cr9Mo Ni2Si V热作模具钢在热处理后的组织演化过程,通过俄歇电子能谱实验,分析了不同回火温度下冲击断口晶界元素的变化。结果表明:铸态钢5Cr9Mo Ni2Si V存在严重的组织偏析,主要是Cr、Mo、Mn和V等合金元素沿原奥氏体枝晶间偏聚,常规热处理工艺虽有所改善,但是无法将其消除,导致回火后组织晶界偏析依然存在,严重弱化了晶界;材料在530℃发生的回火脆性是不可逆的,属于第一类回火脆性;材料产生第一类回火脆性的机理主要是杂质元素P偏聚于晶界,降低了晶界结合力;影响P向晶界偏聚的元素主要有Cr和Mo。
The microstructure evolution of 5Cr9Mo Ni2Si V hot work die steel after heat treatment was studied by means of scanning electron microscopy, metallographic microscope and XRD. The changes of grain boundary elements at impact fracture under different tempering temperatures were analyzed by Auger electron spectroscopy . The results show that the as-cast steel 5Cr9Mo Ni2Si V has serious segregation, mainly segregation of alloying elements such as Cr, Mo, Mn and V along the original austenite dendrites. Although the conventional heat treatment process has been improved, After the tempering, the grain boundary segregation still persists, severely weakening the grain boundary. The temper brittleness of the material at 530 ℃ is irreversible and belongs to the first type of temper embrittlement. The first temper brittleness mechanism of the material The main impurities P segregation in the grain boundary, reducing the grain boundary binding; impact P segregation of grain boundaries mainly Cr and Mo.