Changes in the structure of the surface layer of heavily loaded parts from structural steel with plasma hardening

Abstract

The article presents the research on plasma hardening’s impact on the processes of hardening heavily loaded wear parts of soil-cutting machines. The results of the research showed that in the hardened zone with a thickness of ~ 0.8 mm of a plow share made of 65G structural steel during surface plasma hardening, a gradient-layered (mixed) structure is formed, consisting of a finely dispersed mixture of austenite decomposition products with microhardness decreasing from the surface to the central zones in the interval of 429,3-215,2 HV0.5.
The article confirms the formation of a gradient-layered structure and its properties are due to ultra-high heating and cooling rates during surface plasma treatment, which differs significantly from the processes occurring during traditional heat treatment methods.
The authors established the impact of the parameters of the plasma hardening mode on the main characteristics of the thermal cycle under heating by a plasma arc. The mode is determined to achieve the required depth and rigidity of the surface-modified layer.