18%Cr-12%Mn-0.55%N高氮奥氏体不锈钢低温性能与组织稳定性

Low-Temperature Mechanical Properties and Microstructural Stability of 18%Cr-12%Mn-0.55%N High-Nitrogen Austenitic Stainless Steel

研究了高氮奥氏体不锈钢18%Cr-12%Mn-0.55%N在室温和低温下的力学行为和组织稳定性,并对实验钢的断裂失效行为进行了讨论.低温冲击实验结果表明,实验钢在-70℃前后存在韧脆转变现象,这种脆性类解理断裂是在奥氏体的{111}面发生的;低温拉伸实验结果表明,该钢室温拉伸时即有相变发生,相变产物除α′马氏体外,还发现了一种不同于α′马氏体的相变产物,其结构和相关参数暂不能确定.基于冲击实验和拉伸实验结果可以认为,该钢在-60℃以上有很好的强度和塑性结合,因此其使用温度应该在-60℃以上.

Mechanical behavior and microstructural stability of the high-nitrogen austenitic stainless steel 18%Cr-12%Mn-0.55%N at room/low temperature were investigated with its fracture mechanism discussed. Charpy impact test result showed that the ductile-brittle transformation of the steel specimens takes place at about -70 ℃ and a cleavage-like fracture happens along the {111} facet of austenitic matrix. Furthermore,the tensile test result indicated that a deformation-induced phase transformation happens even at room temperature,from which the products include α＇ martensite and the other one whose structure and relevant parameters cannot be ascertained yet. Based on both the results,it is found that the steel has a good combination of high strength with favorable ductility when it is used at over -60 ℃.