焊接参数对YG16硬质合金/35CrMo钢异质金属焊接接头组织与性能的影响

Influence of welding parameters on the microstructure and properties of welded joint on YG16 cemented carbide/35CrMo dissimilar metals

采用BAg50CuZnCd银基钎料作为填充金属,对YG16硬质合金与35CrMo钢进行了高频感应钎焊连接,并分析了焊接温度、加热速度、保温电流和保温时间共16种工艺参数组合对接头显微组织和力学性能的影响规律。研究结果表明:典型接头硬质合金侧界面基本保持原始的硬质合金组织结构,主要是由WC颗粒及Co(s,s)组成,焊缝主要是由Ag(s,s)和Cu(s,s)的共晶组织组成。焊接温度对接头显微组织的影响最为显著。随着焊接温度的升高,焊缝截面的微观组织中亮色Ag基固溶体所占比例越来越小,而灰色片状Cu基固溶体所占比例越来越大。焊接温度和保温时间对接头的剪切强度影响较大,加热速度和保温电流对接头的剪切强度影响不大。接头的剪切强度随着Cu基固溶体含量的增加而升高。由于Cu基固溶体的硬度较高,其含量增加到一定程度时,接头的脆性增大,剪切强度开始降低。所有接头焊缝处的显微硬度值均稳定在210 HV左右,当焊接温度、加热速度、保温电流、保温时间增大时,焊缝中的Cu(s,s)的含量增加,焊缝的硬度值也随之增加。最优参数组合为焊接温度700℃,加热速度20℃/s,保温电流300 A,保温时间20 s,此时接头的强度达到最大值。

High-frequency induction brazing is performed on YG16 hard alloy and 35CrMo steel with BAg50CuZnCd silver-based brazing filler metal,and the influence of 16 process parameter combinations,including welding temperature,heating speed,holding current,and holding time,on the microstructure and mechanical properties of the joint is analyzed.Research results indicate that the typical joint at the hard alloy side maintains the original hard alloy microstructure,mainly composed of WC particles and Co(s,s),while the weld joint is mainly composed of eutectic structures of Ag(s,s)and Cu(s,s).The welding temperature has the most significant effect on the microstructure of the joint.As the heating temperature increases,the proportion of bright Ag-based solid solution in the microstructure of the weld cross-section decreases,while the proportion of gray lamellar Cu-based solid solution increases.The welding temperature and holding time significantly affect the shear strength of the joint,while the welding speed and holding current have little effect on the shear strength of the joint.The shear strength of the joint increases with the increase of Cu-based solid solution content.Due to the high hardness of Cu-based solid solution,when its content increases to a certain extent,the brittleness of the joint increases and the shear strength begins to decrease.The microhardness of all joint welds remains stable at around 210 HV.As the welding temperature,heating rate,holding current and time increase,the content of Cu(s,s)in the weld increases,and the hardness of the weld also increases.The optimal parameter combination covers a welding temperature of 700℃,heating speed of 20℃/s,holding current of 300 A,holding time of 20 s,thus achieving a top strength of the joint.