高速钢/结构钢双金属复合材料界面研究

Study on Interface of High Speed Steel/Structural Steel Bimetal Composite

采用镶铸法 ,以液固结合的方式制备了高碳钒系高速钢 /结构钢双金属复合材料。研究了不同结合条件下 ,双金属复合材料界面结构及形态。试验结果表明 ,镶铸是靠外层合金带入的过热热量来获得界面结合的 ,当外材与芯材在体积比大于 8.0的条件下 ,才有可能获得界面结合 ,其界面结合为扩散结合。复合材料界面结构由芯材扩散层、激冷凝固层、方向性生长层和胞状晶粒层组成。外层材料凝固时有明显的方向性生长 ,其液固相线推移速度对在液固结合条件下外层材料的凝固组织具有明显影响。当外材与芯材体积比为 1.2 5时 ,外层材料的凝固速度最快 ,出现了棒状伪共晶组织 ,随体积比的增长 。

High carbon vanadium alloyed high speed steel/structural steel series bimetal composite was prepared through liquid solid bonding by cast in insertion. The microstructure and morphology of interface of bimetal composite were studied under different bonding conditions. The results show that interface bonding is dependent on superheated outer layer alloys in cast in insertion. It is possible to obtain interface bonding in volume ratio of outer/core materials greater than 8.0, and the bonding mechanism is diffusion bonding. The interface structure of composite consists of core material diffusion layer, chilling solidified layer, directional growth layer, and cellular granular layer. The apparent directional growth is found during solidification process of outer material.The advanced velocity of liquidus solidus has obviously effect on solidification structure of outer material. With 1.25 volume ratio of outer/core material, the fastest solidification velocity of outer material exhibits the rod like pseudo eutectic microstructure in composite. HSS solidification microstructure changes into prolonged cellular grain along the radial heat transfer direction with the increase of volume ration.