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Mn—Mo—Co马氏体时效钢是为节镍节钻而设计的一种新的马氏体时效钢,虽然强度可以达到甚至超过马氏体时效钢的水平,而韧性却低的多。其主要原因是时效前已有大量析出相沿晶界分布。为改善其性能,本文研究了液态激冷Mn、Mo、Co马氏体时效钢的组织结构,时效温度与部分机械性能的关系。 实验结果表明:激冷带具有极细的晶粒和较大的固溶度。由于激冷带保留了液态的大量空位和位错,因此,形成了明显的胞状组织,激冷带的横断面分为上,下两层,在接近辊面的激冷层内,为直径小于1μm的细等轴晶,其上部为细柱状晶的组织。并发现激冷层为韧性断口,柱晶层为解理断口。经时效处理后,其硬度普遍高于相同成份的淬火钢的时效硬度。关于液态激冷钢铁微晶材料的机械性能有待进一步研究。
Mn-Mo-Co martensitic aged steel is a new martensitic steel designed for nodules, although its strength can reach or exceed the level of martensite aged steel, but the toughness is much lower. The main reason is that there are a large number of precipitates along the grain boundary before aging. In order to improve its performance, the paper studies the microstructure, aging temperature and some mechanical properties of liquid quenched Mn, Mo, Co martensitic steel. The experimental results show that the chilling zone has very fine grains and large solid solubility. As the chilling zone retains a large number of liquid vacancies and dislocations, thus forming a clear cellular structure, the cooling zone is divided into the upper and lower cross-section, in the chilled layer near the roller surface, the diameter is less than 1μm fine equiaxed, the upper part of the fine columnar crystal structure. It is found that the chilled layer is a ductile fracture, and the columnar layer is cleavage fracture. After aging treatment, its hardness is generally higher than the same composition of hardened steel aging hardness. The mechanical properties of liquid quenched steel microcrystalline materials need further study.