固溶温度对TP347HFG耐热钢组织和性能的影响

摘要

TP347HFG heat resistant steel with different solution temperature were characterized by OM,SEM,hardness and tensile strength test,and its microstructure and corresponding properties were investigated as well.Results show that the grain size of TP347HFG heat resistant steel decreases as the solution temperature increases.Their crystalline sizes are evenly distributed with the solution temperature at 1 180 ℃,whereas the crystalline sizes increase and unevenly disperse at 1 210 ℃.The second phase of TP347HFG heat resistant steel,which is mainly NbC,is composed of both large particles and small particles.Small second phase precipitate at the grain boundary at 1 180 ℃ and 1 120 ℃,which can strengthen the grain boundaries.Most part of the second phase precipitate at 1 210 ℃ in the grains with simultaneous occurrence of the Ostwald ripening phenomenon,where the particle distribution of small second phase diminishes while that of larger one increases,and thus bringing the change of corresponding fundamental properties.The values of tensile strength and Rpo.2 reach their peaks with the solution temperature at 1 120 ℃ and 1 180 ℃.The elongation property of this material improves while its hardness decreases,as the increasing solution temperature.%采用金相显微镜、扫描电镜、布氏硬度测试、拉伸测试等手段研究了不同固溶温度下TP347H FG钢的组织和性能.结果表明,随着固溶温度升高,TP347HFG耐热钢晶粒度降低,固溶温度为1 180℃时晶粒尺寸、形状均匀;固溶温度为1 210℃时晶粒明显长大,且尺寸不均匀;TP347HFG耐热钢第二相由大颗粒相和小颗粒相组成,其主要成分均为NbC;固溶温度为1 120℃和1 180℃时小颗粒第二相在晶界析出,对晶界强化作用显著,1 210℃时第二相大部分在晶粒内部析出,并有Ostwald熟化现象发生,细小第二相消溶而较大颗粒第二相变大,从而影响基体性能;固溶温度为1 120℃和1 180℃时其抗拉强度和Rp0.2最高,随着固溶温度的升高,伸长率增加而硬度降低.