形变热处理对11Cr3Co耐热钢组织性能的影响

Effect of thermo-mechanical treatment on microstructure and mechanical properties of 11Cr3Co heat resistant steel

为了提高火电发电效率,要求耐热钢在更高的服役温度下保持良好的高温性能。利用扫描电镜(SEM)、透射电镜(TEM)与电子探针(EPMA)等手段,研究了不同变形量的形变热处理对11Cr3Co耐热钢组织性能的影响。结果表明,随变形量的增加,11Cr3Co钢板基体组织得到显著细化,马氏体板条宽度变细,小角度晶界数量减少;在200~700℃拉伸时,不同变形量形变热处理的钢板抗拉强度均得到提升,伸长率略有降低;在400、600℃拉伸时,经20%TMT700-T处理后的钢板抗拉强度分别为299、269 MPa,伸长率分别为19.3%、21.93%,具有优异的综合力学性能。形变热处理钢板组织中的高密度位错能够促进析出粒子数量增加且使40~100 nm M23C6与10~30 nm MX粒子的分布更加均匀弥散,更好地保证了耐热钢组织的高温稳定性。

In order to improve the efficiency of thermal power generation,heat resistant steel is required to maintain good high-temperature performance at a higher service temperature.By means of SEM、TEM and EPMA,microstructures and mechanical properties of 11 Cr3 Co heat resistant steel plate under thermo-mechanical treatment processing(TMTP)were investigated.The results show that with the reduction increasing,the matrix structure of 11 Cr3 Co plate is remarkably refined,the width of lath martensite becomes finer and the number of small angle grain boundaries increases remarkably.The tensile strength of plates treated by TMTP with different reduction are increased and the elongations are decreased slightly at the tensile temperature of 200-700℃.Under the tensile temperature of 400℃and 600℃,the tensile strength of 20%TMT700-T samples are respectively 299 MPa and 269 MPa,and the elongation are 19.3%and 21.93%,thus 11 Cr3 Co plate shows excellent comprehensive mechanical properties.High density dislocation promotes the increase of precipitated particles.The distribution of 40~100 nm M23C6 and 10~30 nm MX particles is more uniform,which ensures the high temperature stability of 11 Cr3 Co steel.