表面活性元素碲调控M42高速钢组织性能的基础研究

碲（Te）在钢中是一个强表面活性元素。大量研究表明Te具有球化MnS夹杂物、细化钢凝固组织、抑制奥氏体晶粒长大的显著效果，以及抑制析出相长大和抑制钢热处理过程脱碳的潜在显著效果。因此，本项目创新性地提出利用表面活性元素Te调控M42高速钢组织性能的新思路，以解决高速钢碳化物不均匀而严重恶化其耐磨性、硬度和韧性等力学性能的问题，以及热处理过程严重脱碳的问题。揭示凝固、淬火和回火过程Te对M42高速钢晶粒尺寸和碳化物类型、形貌、尺寸、分布的影响规律。基于Te在钢中的赋存状态以及碳化物生长动力学，阐明Te细化碳化物的机理。揭示Te对M42高速钢热塑性、硬度和冲击韧性的影响规律，明确Te最优加入量以及对应的最佳锻造温度区间和热处理工艺。另外，揭示Te对M42高速钢氧化脱碳的影响及作用机制。该研究成果将丰富高速钢微合金化处理工艺及理论，提高我国以“碳化物均匀性”为核心的高速钢微观组织控制技术。

Tellurium (Te) is a very strong surface-active element in steel. Numerous studies have shown that surface active element Te can obviously spheroidize MnS inclusions, refine steel solidification microstructure and suppress austenite grain growth, and that Te might suppress precipitate growth and steel decarburization during heat treatment. Therefore, adding surface active element Te to M42 high speed steel to modify its microstructure and properties was proposed in this project, aiming at solving the problems of non-uniform carbides severely deteriorate the wear resistance, hardness, roughness and other mechanical performance of M42 high speed steel as well as severe decarburization during heat treatment. The effects of Te on the grain size and carbide type, morphology, size and distribution of M42 steel during solidification, quenching and tempering will be clarified, respectively. Based on Te status in the steel and carbide growth dynamics, the underlying mechanisms of Te refining carbides will be revealed. By comprehensively considering the effects of Te on the hot ductility as well as the hardness and impact roughness of M42 steel after tempering, the optimal addition of Te in M42 steel and the corresponding forging temperature range and heat treatment technology optimized will be obtained. Furthermore, the effect of Te on the decarburization of solid M42 steel due to oxidation will be clarified and the mechanisms will be revealed. This research will enrich the technology and theory of high speed steel microalloying, improve the ability of controlling high speed steel microstructure, where carbide uniformity is taken as the core, in our country.