Integrative Process Of Vacuum Brazing And Heat-treating For YG6C Cemented Carbide And Cr12 Steel

In this paper,vacuum brazing and heat-treating integration process between YG6C cemanted carbides and Cr12 steel with two kinds of different compositions CuMnCo filler metal(CuMnCo~①and CuMnCo~②) has studied. Through wettability test,three-point bending test,OM,micro hardness tester,SEM and EDS. The effects of brazing temperature,brazing clearance,thickness of Ni interlayer and heat-treatment on microstructure and properties of the joint were discussed.The wettability test shows that the CuMnCo~①filler metal and CuMnCo~②filler metal has excellent wettability to the substrates.By the organization and EDS analysis knowable,The Cu-Mn based solid solution in the middle area of the brazing seam has good plastic, which can release the residual stress of the joint.And Fe-Co based solid solution generated in two reaction areas can effectively strengthen the metallurgical bonding of the parent materials and the filler metal.If brazing at a too low temperature, the element diffusion ability is weak, and the properties of the joint is poor, because it's cannot achieve enough metallurgical combination,and the jiont fracture in the middle area of the brazing seam.There are lots of Fe-Co based solid solution generated in two reaction areas when the brazing temperature is too high. Much of the reaction product reduce the plastic of brazing seam, and make the ability of release residual stress poor. And the properties of the joint is poor, the jiont fracture on the cemanted carbides near by the brazing seam. By CuMnCo~①filler metal brazing,the best brazing temperature is 1110℃, in which the bending strength reaches about 508 MPa. By CuMnCo~②filler metal the best brazing temperature is 1100℃, in which the bending strength reaches about 408 MPa.When the brazing clearance is too narrow, a great number of Fe-Co based solid solution not only generated in two reaction areas,but also in the middle area of the brazing seam, which can decrease the plasticity of the brazing seam and the axial residual stress releasing capacity, and the jiont fracture on the cemanted carbides near by the brazing seam, the properties of the joint is poor. When the brazing clearance is too wide, the long-range diffusion of substrates elements is difficult and the metallurgical bonding of the joint is much weaker.So,there exists an optimal brazing clearance.By CuMnCo~①filler metal brazing,the best brazing clearance is 0.2 mm when brazing at the best temperature 1110℃, in which the bending strength reaches about 508 MPa. By CuMnCo~②filler metal the best brazing clearance is 0.16 mm when brazing at the best temperature 1100℃, in which the bending strength reaches about 487 MPa.As the Ni interlayer added in the brazed joint, the long-range diffusion of substrates elements is hindered.The joint metallurgical combination ability decline. In particular there are no Fe-Co based solid solution in the reaction areas close to YG6C cemanted carbides.And the joint fracture position here when doing three-point bending test.Using CuMnCo~①filler metal after quenching, the bending strength of the joint has declined, but it is still can reach 483 MPa, YG6C cemanted carbides and Cr12 steel obtain higher hardness. The integrative Process of Vacuum Brazing and Heat-treating for YG6C cemented carbide and Cr12 steel is reasonable and feasible.