3.5NiCrMoV钢的离子渗氮层

Ion-nitriding of 3.5NiCrMoV Steel

对经正火和860℃油淬、640℃回火的含0.25%C、3.75%Ni、1.62%Cr、0.33%Mo和0.09%V(质量分数)的3.5NiCrMoV钢,分别在520℃、550℃、570℃离子渗氮18h。检测了渗氮层的组织、表面硬度和硬度梯度及基体组织。试验结果表明:在520〜570℃离子渗氮的3.5NiCrMoV钢基体组织没有明显变化;随着渗氮温度的提高,渗层深度增加表面硬度下降。此外,采用硬度法测定的渗氮层深度与采用金相法测定的基本一致。

;After being normalized,quenched form 840℃in oil and then tempered at 640℃,3.5NiCrMoV steel containing 0.25%C,3.75%Ni,1.62%Cr,0.33%Mo,and 0.09%V(by mass)was ion nitrided at 520℃,550℃and 570℃for 18 h respectively.Microstructure,surface hardness,hardness gradient of the ion-nitrided layer as well as hardness of the matrix were measured.The results demonstrated that as nitriding temperature became higher,the case depth increased,and the surface hardness decreased,and that the 3.5NiCrMoV steel ion-nitrided at 520℃ to 570℃ had no evident change in hardness of the matrix.Furthermore,the case depth measured by test was basically in accord with that measured by metallographic test.