Cr_(3)C_(2)含量对热压烧结WC基硬质合金材料微观组织和力学性能的影响

Effects of Cr_(3)C_(2) content on microstructure and mechanical properties of hot-pressed sintered WC based cemented carbides

为了研制高强度高硬度的硬质合金刀具材料,本文采用真空热压烧结技术制备Cr_(3)C_(2)含量不同的WC基硬质合金。通过XRD、SEM、EDS等分析手段研究其物相组成及微观形貌,探究Cr_(3)C_(2)含量对WC基硬质合金力学性能和微观组织的影响规律。结果表明:在WC-Co硬质合金中添加适量Cr_(3)C_(2)可有效抑制WC晶粒异常长大,提高晶粒均匀度,减少微观组织缺陷,进而改善其综合力学性能。随Cr_(3)C_(2)含量增加,合金的硬度和抗弯强度先升高后降低,断裂韧性先降低后升高。当Cr_(3)C_(2)的质量分数为0.4%时,WC基硬质合金综合力学性能最佳,硬度(HV)达到20.97 GPa,抗弯强度为1584 MPa,断裂韧性为10.92 MPa·m^(1/2),其中硬度大幅提高对于硬质合金材料用作切削刀具具有重要意义。

In order to develop cemented carbide tool materials with high strength and high hardness,WC-based cemented carbides with different Cr_(3)C_(2)contents were prepared by vacuum hot-pressed sintering technology.The phase compositions and microstructures of the WC-based cemented carbides were studied by XRD,SEM,and EDS.The effect of Cr_(3)C_(2)content on the mechanical properties and microstructures of WC-based cemented carbide were investigated as well.The results show that appropriate amount of Cr_(3)C_(2)can effectively inhibit the abnormal growth of WC grains,improve grain uniformity,reduce microstructure defects,and improve its comprehensive mechanical properties.With the increase of Cr_(3)C_(2)content,the hardness and bending strength of the alloys increase firstly and then decrease,and the fracture toughness first decreases and then increases.When the mass fraction of Cr_(3)C_(2)is 0.4%,the WC based cemented carbide has the best comprehensive mechanical properties,with the hardness(HV)of 20.97 GPa,bending strength of 1584 MPa,and fracture toughness of 10.92 MPa·m^(1/2).