热处理工艺对Fe-12Cr马氏体钢组织与力学性能的影响

Effect of heat treatment on microstructure and mechanical properties of Fe-12Cr martensitic steel

对Fe-12Cr马氏体钢包壳管材分别进行980~1050℃下保温15~30 min正火处理,随后在730~790℃温度下进行2 h回火处理,研究不同热处理工艺对Fe-12Cr马氏体钢包壳管材微观组织、室温和高温力学性能的影响。结果表明:正火处理后,冷轧Fe-12Cr马氏体钢的组织为板条马氏体,冷轧态的碳化物粒子会部分固溶于马氏体基体中;随正火温度的升高,残余碳化物的含量降低,且原奥氏体晶粒尺寸会增大(从980℃的9μm增至1050℃的12μm);回火处理后,马氏体基体上重新析出细小碳化物粒子,且随回火温度增加,碳化物粒子会发生粗化,平均尺寸为0.2~0.28μm,而马氏体板条间距几乎不随回火温度发生变化。Fe-12Cr马氏体钢经过1050℃×15 min正火+760℃×2 h回火处理后具有最佳的综合力学性能,其在600℃下的屈服强度为270 MPa,伸长率为40%;此时合金的碳化物粒子体积百分数最高,约为4.5%。

Fe-12Cr martensitic steel cladding tubes were treated by normalizing at 980-1050℃for 15-30 min and then tempering at 730-790℃for 2 h,and the effects of different heat treatment processes on microstructure,room temperature and high temperature mechanical properties of the Fe-12Cr martensite steel cladding tubes were investigated.The results show that after normalizing treatment,the microstructure of the cold rolled Fe-12Cr martensite steel is lath martensite,and the carbide particles will partially dissolve in martensite matrix.With the increase of normalizing temperature,the content of residual carbide decreases,and the grain size of primary austenite increases(from 9μm at 980℃to 12μm at 1050℃).After tempering treatment,the fine carbide particles are reprecipitated in the martensite matrix,and with the increase of tempering temperature,the carbide particles is coarsened,the average size is 0.2-0.28μm,while the martensite lath spacing almost does not change with the tempering temperature.The Fe-12Cr martensite steel has the best comprehensive mechanical properties after normalizing at 1050℃for 15 min and tempering at 760℃for 2 h,its yield strength is 270 MPa and elongation is 40%at 600℃,and the carbide particle volume percentage of the alloy is the highest,which is about 4.5%.