固溶处理对冷轧Cr-Mn-N奥氏体不锈钢组织性能的影响

Effect of solution treatment on microstructure and properties of a cold-rolled Cr-Mn-N austenitic stainless steel

对一种节镍型Cr-Mn-N奥氏体不锈钢(Fe-13.8%Cr-11%Mn-0.35%N)的固溶处理工艺进行研究,设计固溶温度为800~1100℃,保温时间为10、20和30 s,冷却方式为水冷和空冷。结果表明,试验钢经过900℃保温30 s水冷后,综合力学性能最佳,其中断后伸长率为47.7%,抗拉强度为1023 MPa,屈服强度为540 MPa,强塑积为48.8 GPa·%。当固溶温度为800℃时,塑性提升并不明显,主要由于该温度仍处于敏化温度区间,导致含铬碳化物析出于奥氏体晶界,这对试样的塑性具有不利影响。根据EBSD的统计结果,经过900℃保温30 s后,试样组织中晶粒十分细小且均匀,平均晶粒尺寸约为1.4μm;而提高固溶温度会导致晶粒粗化,1000℃保温30 s后试样平均晶粒尺寸约为2.1μm,1100℃保温30 s后平均晶粒尺寸约为9.2μm。

Solution treatment of a low-nickel Cr-Mn-N austenitic stainless steel(Fe-13.8%Cr-11%Mn-0.35%N)was investigated.The solution temperatures were 800~1100℃,the holding time was 10,20 and 30 s,and the cooling methods were water cooling and air cooling,respectively.These results showed that after solution treatment at 900℃for 30 s under water cooling,the best comprehensive mechanical properties of experimental steel were obtained with the elongation after fracture of 47.7%,tensile strength of 1023 MPa,yield strength of 540 MPa,and product of strength and elongation of 48.8 GPa·%.However,the increase of ductility was not obvious after solution treatment at 800℃,because the temperature was still in the range of sensitization temperature,resulting in the precipitation of a type of chromium carbide along grain boundaries,which had a negative impact on the plasticity of the sample.According to the statistical results by using EBSD,the austenitic grains were very fine and uniform after solution treatment at 900℃for 30 s with the average grain size of 1.4μm.Besides,increasing temperature can lead to grain coarsening.The average grain size was 2.1μm after solution treatment at 1000℃for 30 s,and that was 9.2μm after solution treatment at 1100℃for 30 s.