Microstructure and Properties of Ferrous Powder Sintering Forging Steel with Different Cr Content
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摘要: 通过添加铬铁合金粉的形式将铬元素引入到Fe-Ni-Mo预合金粉中，经冷压烧结、热锻、淬火、回火等工序制备得到含有不同质量分数（0，0.35%，0.55%，1.00%，1.50%）铬的铁基粉末烧结锻造钢，研究了此钢的显微组织、密度、力学性能和耐磨性能。结果表明：冷压烧结钢的组织为铁素体+珠光体，经冷压烧结、热锻和淬火后的组织为马氏体，再经回火后的组织为回火索氏体，当铬质量分数0.55%时，试验钢组织的均匀性最好；烧结锻造钢的硬度、密度、抗拉强度和伸长率均大幅度高于冷压烧结钢的，磨损率降低；当铬质量分数为0.55%时，烧结锻造钢具有最佳的综合性能，密度为7.74 g·cm-3，硬度为712 HV，抗拉强度为1 310 MPa，伸长率为5.98%，磨损率为7.01×10-13 m3·N-1·m-1；其拉伸断口具有韧窝特征，但宏观断裂形式为脆性断裂，磨损机制主要为剥层磨损和磨粒磨损。Abstract: The chromium element was introduced into Fe-Ni-Mo pre-alloyed powder by adding chromium-iron alloy powder, and then ferrous powder sintering forging steels containing different mass fractions (0, 0.35%, 0.55%, 1.00%, 1.50%) of chromium were prepared by cold pressing sintering, hot forging, quenching and tempering. The microstructure, density, mechanical properties and wear resistance of the steels were studied. The results show that the microstructure of the steel by cold pressing sintering consisted of ferrite and pearlite; after hot forging and qanching, the microstructure of martersite was obtained; after tempering, the microstructure was composed of tempered sorbite. The microstructure of the sintering forging steel with chromium of 0.55wt% was the most uniform. Compared with the steel after cold pressing sintering, the hardness, density, tensile strength and elongation of the sintering forging steel got improved greatly, and wear rate decreased. When the content of chromium was 0.55wt%, the tested steel had the best comprehensive performance, including density of 7.74 g·cm-3, hardness of 712 HV, tensile strength of 1 310 MPa, elongation of 5.98%, and wear rate of 7.01×10-13 m3·N-1·m-1. The tensile fracture had dimple characteristic, but the macroscopic fracture mode was brittle fracture. The wear mechanism mainly consisted of delamination wear and abrasive wear.
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Keywords:
- powder metallurgy /
- Cr-Fe powder /
- microstructure /
- mechanical property /
- wear resistance
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