A hot-compression bonding method for manufacturing large high-speed homogeneous steels

Hot-compression bonding with subsequent soaking treatment is employed to manufacture large high-speed homogeneous steels in the current study. The effects of the deformation temperature (1050, 1100, and 1150 ℃), strain (10%, 30%, and 50%), and holding time (1 and 12 h) on the interfacial microstructure and tensile strength of joints were investigated. The results indicated that complete bonding occurred at 1050 ℃/50%, 1100 ℃/30%, 1100 ℃/50%, 1150 ℃/30%, and 1150 ℃/50%, and the tensile strength of the obtained joints was comparable to that of the base material. In other cases, interfacial voids were formed along the straight interface, which deteriorated the bonding strength. These voids were eliminated by a post-holding treatment at 1150 ℃ for 12 h, promoting the transformation of a straight interface to bulged grain boundaries. This resulted in the complete healing of the interface, except for samples bonded at 1050 ℃/10%. The bulging of the original bonding interface due to the plastic deformation and atomic diffusion was the main mechanism for interfacial healing. Stable interfacial oxide nanoparticles were formed under a high vacuumand did not affect the recovery of joint strength. To validate the practicality of this method, an integrated high-speed steel with a homogeneous tensile strength was manufactured by
bonding four pieces of blanks.