Cr的添加方式与含量对粉末冶金烧结钢组织及力学性能的影响

摘要

Adding 430L stainless steel powder and CrFe alloy powder to the based powder Fe-1.75Ni-1.5Cu-0.5Mo-0.6C, respectively. Then high temperature sintered hardening process were used to fabricate chromium containing powder metallurgic steel Fe-1.75Ni-1.5Cu-xCr-0.5Mo-0.6C (x=0.5, 1.0, 0.5). The effects of Cr content and addition method on the microstructure and mechanical properties of the sintered steel were investigated. The results show that, compared with adding Cr-Fe alloy powder, the strengthening effect of alloy through adding 430L stainless steel powder for adding Cr is better, and this adding method is adopted to fabricate chromium containing powder metallurgy steel. With increasing chromium content, tensile strength increases first and then decreases, while elongation decreases and hardness increases steadily. The material with 1.0%Cr has the best properties, and green density, sintered density, tensile strength, elongation and Rockwell hardness are 7.18 g/cm3, 7.20 g/cm3, 910 MPa, 2.0% and 30 HRC, respectively. Microstructure of the sintered alloy steel is mainly composed of pearlite, bainite and martensite. The fracture of the material is a mixed ductile-brittle fracture.%在Fe-1.75Ni-1.5Cu-0.5Mo-0.6C粉末中，分别以添加430L不锈钢粉和CrFe合金粉的方式加入Cr元素，采用高温烧结硬化工艺制备含铬烧结钢 Fe-1.75Ni-1.5Cu-xCr-0.5Mo-0.6C(x=0.5，1.0，1.5)，研究铬的添加方式与含量对烧结钢组织与力学性能的影响。结果表明，与添加CrFe合金粉的方式相比，采用添加430L不锈钢粉的方式时，Cr的强化效果更好。采用该方式制备的含Cr烧结钢，随Cr含量增加，抗拉强度先上升后下降，伸长率不断下降，硬度不断提高，含铬量1.0%的材料具有良好的综合性能，生坯密度和烧结密度分别为7.18 g/cm3和7.20 g/cm3，抗拉强度、伸长率和硬度分别达到910 MPa、2.0%和30 HRC；烧结钢组织主要以珠光体、贝氏体和马氏体为主的混合组织；烧结钢的拉伸断裂以韧–脆混合断裂为主。