Study On The Vacuume Diffusion Bonding In Bimetallic Composite Die Steels

High-carbon and high-alloy cold work die steel has been widely applied in large and medium cold work die at home and abroad, because it possessing high-hardness, high-wear resistant, little deformation after heat treatment and great carrying capacity. But the serous carbide segregation of which is apt to cause directional deformations, strength-toughness decreasing. Instead by bimetal composite die steel that fabricated using high-hardness cold work die steel and high-toughness alloy structure steel can overcome the defects mentioned above, save source and reduce cost. Various approached are applied in the course of manufacturing bimetal composite die steel, such as hot forged-rolled welding, explosive welding and vacuum diffusion welding are applied, among which, the vacuum diffusion welding is the optimal.The vacuum diffusion bonding of cold work die steel Cr12MoV and high speed steel W6Mo5Cr4V2 (M2) with alloy spring steel 50CrVA ,alloy structure steel 40Cr and high speed steel M35 was studied by means of hardness test, tensile test, bending test, SEM ,EDX and OM analysis and micro-hardness test.Sound metallurgical bonding was obtained between the two dissimilar materials of Cr12MoV/50CrVA,M2/50CrVA at 1150℃for 30 minute, bonding pressure is 20MPa and the vacuum level is less than 1.0×10-1Pa; The fracture of tensile test and bending test both took in place on the Cr12MoV and M2, which have higher hardness and wear-resistance. therefore, it can be seen that the strength of bonding zone is higher than Cr12MoV and M2 matrix.Sound metallurgical bonding was obtained between the two dissimilar materials of Cr12MoV/40Cr,M2/40Cr at 1100℃for 30 minute, bonding pressure is 20MPa and the vacuum level is less than 1.0×10-1Pa; The fracture of tensile test and bending test took in place on the Cr12MoV or 40Cr. therefore, it can be seen that the strength of bonding zone is higher than Cr12MoV and 40Cr matrix.Sound metallurgical bonding was obtained between the two dissimilar materials of M2/M35 at 1150℃for 30 minute, bonding pressure is 20MPa and the vacuum level is less than 1.0×10-1Pa; The fracture of tensile test and bending test both took in place on the M2, which have higher hardness and wear-resistance. therefore, it can be seen that the strength of bonding zone is higher than M2 matrix.