Cr-W-Mo-V高合金中高碳钢的显微组织及回火硬度

Microstructure and tempering hardness of Cr-W-Mo-V high alloy medium-upper carbon steel

研究了4种不同成分的Cr-W-Mo-V高合金中高碳钢的显微组织及回火硬度,并以相平衡热力学理论分析讨论了合金含量变化对显微组织及二次硬化的影响。结果表明,该类钢在αγ相变的加热和冷却过程,发生M23C6M6C相互转变,碳化物的溶解和析出过程使之细化分布均匀,在合适的成分比率时淬火未溶碳化物小于0.8μm。而Mo（或W）含量过高会导致碳化物颗粒粗化,V含量过高时出现少量的大块MC碳化物,使其不均匀性加重。该类钢在合适成分比率时回火硬度可达62~64 HRC。提高Mo含量有利于各种碳化物沉淀强化向中间温度靠近,明显提高回火硬度,最高硬度可达66.5 HRC。提高V含量会使沉淀析出的温度分散度加大,使回火硬度降低。

The microstructure and tempering hardness of Cr-W-Mo-V high alloy meddle-upper carbon steels with four different components were studied,and the effect of alloy contents on microstructure and tempering hardness was analyzed and discussed by phase equilibrium thermodynamic theory. The results show that in process of heating and cooling of α γ transformation of these steels,the dissolution and precipitation of M23C6M6C carbides transformation can be used to carbides distributing uniform refinement,such as the undissolved carbide size after quenching is less than 0. 8 μm when the steels composition is under the suitable proportion. The over adding of Mo（ or W） will lead to coarsening of carbide particles,and over adding of V will appear small of the bulk MC carbide,so the heterogeneity of carbides is increasing. Tempering hardness is higher of 62-64 HRC when the steels composition is under the suitable proportion. The increasing of Mo content is benefit to the carbides precipitation strengthening near intermediate temperature,will significantly improve the tempering hardness as the highest hardness can also up to 66. 5 HRC. Increasing V will make the dispersion degree of precipitation temperature increase,so the tempering hardness will decrease.