氮元素对马氏体不锈钢组织和性能的影响

Effect of nitrogen element on microstructure and properties of martensitic stainless steel

研究了马氏体不锈轴承钢经添加氮元素及热处理后的微观组织和力学性能。结果表明,经过相同的热处理后,高氮马氏体不锈轴承钢比没有经过氮合金化处理的马氏体不锈钢具有更高的抗拉强度、屈服强度和硬度,分别提高了20%、26%和21%;同时冲击韧性没有明显降低。组织观察发现,经过氮合金化及热处理后,马氏体不锈轴承钢中的析出碳化物得到了细化。最大碳化物尺寸由25μm降低至5μm,碳化物平均尺寸由882 nm降低至592 nm,碳化物所占面积比例由16.0%降低至2.3%。氮元素的固溶强化和细小析出相的沉淀强化是造成高氮马氏体不锈轴承钢综合性能提高的原因。

Microstructure and mechanical properties of martensitic stainless steel during the process of nitrogen alloying and heat treatment were investigated.The results indicate that after the same heat treatment systems,nitrogenous martensitic stainless steel has higher ultimate tensile strength（ UTS）,yield strength（ YS） and hardness（ enhanced by 20%,26% and 21%,respectively）,compare with the steel without nitrogen alloying,meanwhile the impact toughness decreases slightly.Optical microscope（ OM） and transmission electron microscopy（ TEM） observations show that refining carbides are obtained in the N-alloyed specimen,and the maximum size of the carbide decreases from 25 μm to 5 μm and the average grain size of the carbide is reduced from 882 nm to 592 nm.The volume fraction of the carbides decreases from 16.0% to 2.3%.The solid solution strengthening of N and precipitation strengthening of fine precipitate are responsible for the improved combination property of the nitrogenous martensitic stainless steel.