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本文研究了混合稀土对Fe—Mn粉末热锻钢性能与组织的影响。试验结果表明,在雾化预合金钢粉前加入0.02～0.15混合稀土,对钢粉的压缩性和压溃密度没有明显的影响,但能提高压溃强度,改善成型性能,改变锻钢中夹杂物的大小与分布,并能显著提高钢的强度与冲击韧性、改变冲击断口形态,消除淬火开裂现象。电子探针分析表明在原始粉末颗粒表面有稀土锰复合氧化物,它有利于烧结、减少间隙,强化颗粒间界。当稀土含量较低时,这种复合氧化物强烈地抑制合金元素的扩散,造成合金元素的不均匀分布,得到不均匀金相组织。抑制合金元素扩散的能力随稀土加入量的增加而降低,因此要得到均匀金相组织必须提高还原温度和延长高温烧结时间。
In this paper, the effect of mixed rare earth on the properties and microstructure of Fe-Mn powder hot-forged steel was studied. The results show that the addition of 0.02 ~ 0.15 mixed rare earth before atomizing the prealloyed steel powder has no obvious effect on the compressibility and crush density of the steel powder, but it can improve the crush strength, improve the formability and change the inclusions in the forged steel The size and distribution of materials, and can significantly improve the strength and impact toughness of steel, change the impact of fracture morphology, to eliminate quenching and cracking phenomenon. Electron probe analysis showed that rare earth manganese composite oxide was present on the surface of the original powder particles, which was conducive to sintering, reducing the gap and strengthening the grain boundary. When the content of rare earth is low, this composite oxide strongly inhibits the diffusion of alloying elements, resulting in the non-uniform distribution of alloying elements, resulting in an uneven microstructure. The ability to suppress the diffusion of alloying elements decreases with the addition of rare earth, so to obtain uniform microstructure, the reduction temperature must be increased and the sintering time prolonged.