硬质合金真空钎烽的研究

为了提高盾构隧道掘进机硬质合金刀头和钢基体的连接强度及使用寿命，选用801钎料，对42CrMo钢与WC-8％C0硬质合金进行真空钎焊试验，研究钎焊温度和钎焊压力对钎焊接头性能的影响，并用剪切试验确定最佳工艺参数。通过使用扫描电镜观察显微组织及能谱分析钎料中各元素在母材中的扩散情况，探讨了该钎料与母材的结合性能。结果表明，采用60kPa的压力在980℃下钎焊，钎料形成的中间，层与母材结合较好，无裂纹等缺陷，连接层厚约40-50mm；剪切强度达到415MPa，Zn与Mn发生了向硬质合金中的明显扩散，Co偏聚于连接层与钢的界面；压力的适当增加有利于提高界面结合强度，但压力过高导致连接层变薄，不利于缓解接头热应力。

Research on Vacuum Brazing of Cemented Carbide

In order to improve the joining strength and service life of the cemented carbide cutter and the steel base used for the shield tunnel boring machine, the vacuum brazing tests of 42GrMo steel and WC-8%Co cemented carbide were carried out to study the effects of brazing temperature and pressure on the properties of the brazing joints and determine the optimal process parameters by using shear test. By means of scanning electron microscope and energy dispersive spectrometer, the microstructure of the joints and the situation of the filler metal diffusing into the base materials for each element were investigated. Furthermore, the bonding properties of the idler with the base materials were studied. The results suggest that the interlayer formed by filler under the brazing pressure of 60 kPa at 980 ~C joins the base materials well without cracks and other defects; the interlayer thickness is of about 40-50 mm and the shear strength reaches 415 MPa. Zn and Mn apparently diffuse into the cemented carbide; Co accumulates at the interface between the interlayer and the steel Appropriately increasing the brazing pressure can improve the bonding strength, but if the pressure is too high, the interlayer becomes very thin, which is not beneficial to ease the thermal stress in the joint.