深冷处理对中高钴硬质合金性能及组织的影响

Influence of Cryogenic Treatment on the Performance and Microstructure of Cemented Carbide with Medium and High Cobalt Content

采用常规硬质合金生产工艺制备了YG11C﹑YG20C和MB50A3种WC-Co硬质合金牌号试样,研究了深冷处理对3种硬质合金牌号性能和组织的影响。采用SEM分析深冷后合金的微观组织变化,用X衍射分析合金的钴相转变和晶格常数的变化,对深冷前后的3种合金进行了冲击韧性试验。结果表明:深冷处理对合金的磁力、钴磁、硬度和密度几乎无影响,但是会小幅度提高硬质合金的抗弯强度,同时使合金的冲击韧性提高10%以上,深冷处理后合金的微观组织也无明显变化,深冷处理会促使面心立方Co向密排六方Co的转变,但不会影响面心立方钴的晶格常数。

Three kinds of cemented carbide grade samples of YG11C, YG20C and MB50A were produced by using conventional production process of cemented carbide. Effect of cryogenic treatment on the performance and microstructure of cemented carbides was investigated. The microstructure change after cryogenic treatment was analyzed using SEM. Co phase transition and the change of fcc-Co lattice constant were studied by X-ray diffraction. The impact toughness was tested on three kinds of alloys before and after cryogenic treatment, respectively. The results show that cryogenic treatment has almost no effect on the magnetic, cobalt magnetic, hardness and density. But the bending strength is improved a little. The toughness is also increased by 10% after cryogenic treatment. The mierostructure of the alloys has no obvious change, although cryogenic treatment can lead to fcc-Co to hcp-Co phase transition. It will not affect the lattice constant of fcc-Co in cemented carbide.