碳含量对亚微晶WC-12%Co硬质合金组织与性能的影响  

Effect of Carbon Content on the Microstructure and Properties of Submicron WC-12%Co Cemented Carbide

作　　者：龚红 刘恒嵩 鄢志刚 李微 林森 梁瑜 GONG Hong;LIU Hengsong;YAN Zhigang;LI Wei;LIN Sen;LIANG Yu(Jiangxi Jiangwu Hard Alloy Co.,Ltd.,Jing'an 330699,Jiangxi,China;Jiangxi Tungsten Industry Holding Group Co.,Ltd.,Nanchang 330006,Jiangxi,China)

机构地区：[1]江西江钨硬质合金有限公司,江西靖安330699 [2]江西钨业控股集团有限公司,江西南昌330006

出　　处：《中国钨业》2024年第5期33-39,共7页China Tungsten Industry

基　　金：江西钨业控股集团有限公司重大科技专项(JWGF-22ZD-01,JWGF-23ZD-01)。

摘　　要：采用3种不同碳含量的W-C-Co混合料,通过压制-低压烧结制备3种不同碳含量、晶粒度0.6μm的WC-12%Co亚微晶硬质合金棒材,研究了不同的碳含量对硬质合金组织与性能的影响。采用万能试验机测试材料的抗弯强度,采用维氏硬度仪进行维氏硬度及Palmqvist压痕试验测试材料的硬度和计算材料断裂韧性,采用扫描电镜(SEM)观察材料的微观组织、WC晶粒形貌、裂纹扩展情况。结果表明,硬质合金的碳含量会影响烧结过程中WC晶粒的长大,随着WC粉末中碳含量从6.12%增加到6.20%,合金中WC晶粒逐渐长大,部分晶粒最终呈现平板状;随着合金碳含量的升高,从合金的断裂韧性压痕裂纹观察到裂纹偏转以及穿晶断裂数量显著增加,以此阻碍裂纹扩展,从而提高合金的韧性。随着合金的碳含量减少,合金的钴磁下降,合金硬度随合金钴磁下降而增加,当合金钴磁为9.56%时,WC-12%Co硬质合金具有较好的综合力学性能,其硬度(HV_(30))为1690,抗弯强度和断裂韧性分别为4690 MPa和9.9 MPa·m^(1/2)。An experimental research was conducted on submicron WC-12%Co cemented carbide rod products with a grain size of 0.6μm.Three types of W-C-Co mixtures with different total carbon contents were utilized to prepare WC-12%Co cemented carbides with varying magnetic saturations through pressing and low-pressure sintering.Scanning Electron Microscopy(SEM)was employed to observe the microstructure,WC grain morphology,and crack propagation behavior of the materials.Universal testing machines and Vickers hardness testers were used to measure the flexural strength,fracture toughness,and hardness of the materials.The influence of different total carbon contents on the microstructure and properties of the cemented carbides was investigated.The results showed that the total carbon content in the alloy affected the growth of WC grains during sintering.As the carbon content increased from 6.12%to 6.20%,the WC grains gradually grew,with some grains eventually exhibiting a tabular shape.From indentation crack observations on the fracture toughness of the alloy,a significant increase in crack deflection and transgranular fracture was observed,which hindered crack propagation and thus improved the alloy's toughness.As the total carbon content of the alloy decreased,the cobalt magnetism of the alloy also decreased,and the hardness of the alloy increased accordingly.When the cobalt magnetism of the alloy was 9.56%,the WC-12%Co cemented carbide exhibited superior comprehensive mechanical properties,with a hardness(HV_(30))of 1690,flexural strength of 4690 MPa,and fracture toughness of 9.9 MPa·m^(1/2).

关 键 词：碳化钨 晶粒形貌 碳含量 增韧机制 显微组织 

分 类 号：TG135.5[一般工业技术—材料科学与工程]