Ni含量对0Cr17Ni4Cu4Nb不锈钢富铜相析出的影响

研究了不同Ni含量的0Cr17Ni4Cu4Nb不锈钢在1040℃固溶后油冷和炉冷(均进行480℃时效,分别表示为OC、FC试样)两种热处理工艺下的力学性能和微观组织变化规律,通过力学性能测试、SEM和TEM观察,探讨了Ni含量对力学性能和富铜相析出的影响.研究表明:FC试样的强度由于炉冷过程中析出了粗大的富铜相而显著低于OC试样的；随Ni含量的提高,两种试样的强度均增加,但差距在缩小,其原因是炉冷过程中析出的富铜相尺寸逐渐细小,表明Ni可以提高了Cu在γ相区的溶解度,延缓了固溶后炉冷过程中的富铜相析出；随时效温度的提高,不同Ni含量试验钢的强度降低,且Ni含量高的试验钢强度降低更显著；随Ni含量的提高,时效过程中富铜相的形核速率和长大速度增加,表明Ni降低了Cu在钢中的扩散激活能.

Effect of Ni content on precipitation of Cu-rich phase in 0Cr17Ni4Cu4Nb stainless steel

The mechanical properties and microstructure of 0Cr17Ni4Cu4Nb stainless steels with various Ni content after the heat treatments of solid solution at 1040 ℃,and then oil cooling(OC sample) or furnace cooling(FC sample) and both aged at 480 ℃ were studied,and the effect of Ni content on both the mechanical properties and the precipitation of Cu-rich phase were investigated by means of mechanical properties tests,SEM and TEM analysis.The experimental results show that the strength of FC sample is lower than that of OC sample significantly due to precipitation of coarser Cu-rich phases in the steel during the slow cooling in furnace.The strength of both samples improved with increasing of Ni content,and the difference of strength between OC and FC sample is reduced due to the size of Cu-rich phase getting smaller gradually during the process of slow cooling after solid solution with increasing of Ni content.It means that Ni element may increase the solubility of copper in γ phase zone,which postponed the precipitation of Cu-rich phases during the process of slow cooling after solid solution.The strength of samples with various Ni content is reduced with increasing of aging temperature,and the degree of reduction in strength was more obvious for the samples with high Ni content.Both the nuclei and growth rate of Cu-rich phase increase during the aging process with increasing of Ni content,it indicate that Ni element may decrease the diffusion activated energy of copper in 0Cr17Ni4Cu4Nb stainless steel.