退火温度对21Cr-0.3Cu铁素体不锈钢组织性能的影响

通过光学显微镜、拉伸试验及背散射电子衍射,研究了退火温度对21Cr-0.3Cu超纯铁素体不锈钢显微组织、力学性能、成形性能和微观织构的影响。结果表明,试验钢经970 ℃退火时,晶粒细小且均匀,组织处于完全再结晶状态。退火温度低于970 ℃时,再结晶不完全;退火温度高于970 ℃时,再结晶晶粒异常长大,这两种情况均出现混晶组织。试验钢在970 ℃退火时,综合力学性能最佳,抗拉强度为473 MPa,屈服强度为315 MPa,伸长率35.7%。随退火温度的升高,试验钢的平均塑性应变比r_m值先增加后减少。当退火温度达到970 ℃时,r_m可以达到最大值1.82。γ纤维织构密度变化趋势与r_m值一致,退火温度为970 ℃时,γ纤维增强明显,此时其取向密度达到最大值f(g)=20.56,成形性能最佳。

Effect of annealing temperature on microstructure and properties of 21Cr-0.3Cu ferritic stainless steel

Effect of annealing temperature on microstructure, mechanical properties, formability, and microtexture of the 21Cr-0.3Cu ultra-pure ferrite stainless steel was studied by means of optical microscope, tensile testing and backscattered electron diffraction. The results show that when the tested steel is annealed at 970 ℃, the grains are fine and uniform, and the structure is in a completely recrystallized state. When the annealing temperature is lower than 970 ℃, the recrystallization is incomplete; while when higher than 970 ℃, the recrystallized grains grow abnormally, and mixed grain microstructure appears in both the cases. When the tested steel is annealed at 970 ℃, the overall mechanical properties are the best, with a tensile strength of 473 MPa, a yield strength of 315 MPa, and an elongation of 35.7%. As the annealing temperature rises, the average plastic strain ratio r_m first increases then decreases, getting the maximum value of 1.82 at 800 ℃. The change trend of the γ texture density is consistent with that of the value of average plastic strain ratio r_m. When the annealing temperature is 970 ℃, the γ texture is reinforced obviously. At this time, its orientation density reaches the maximum value f(g)=20.56, and the forming performance is the best.