Mechanical properties of plasma-hardened 5 chromium tool steel deposited by arc welding: plasma heat treatment promotes an increase in mechanical properties of deposited metal

摘要

A complex technology is proposed to increase the mechanical properties of tools, dies and machine components for hot work of metals. The combination of hardfacing with a 5% chromium deposited metal and subsequent surface treatment using a highly concentrated plasma jet creates a hard surface along with resistance to breakage upon impact. The extremely fine-grained martensite structure and relevant property gradients of the plasma-jet hardened layer are almost identical to those treated by laser and electron beams. Due to rapid phase recrystallization, the dissolution of primary carbides and the saturation of a solid solution with carbon and alloying elements develop. This leads to an increase in the degree of tetragonality, microdistortions of the crystal structure and to an increase in hardness without a decrease in dynamic fracture toughness because of the high dislocation density and mosaic block size reduction. In its mechanical properties, martensitic 5% chromium (0.20% C) deposited metal after plasma hardening is close to chromium hot-work die steels, significantly surpassing them in dynamic fracture toughness.