Influence of the structure of the steel of electroslag remelting on the properties of cemented and nitrided surfaces of machine parts

Abstract

The analysis of the influence of electroslag remelting steel structure on the properties of cemented and nitrided surfaces of machine parts is carried out. It is noted that when using electroslag remelting, the greatest efficiency is achieved in the production of large-sized gearwheels, hardened by cementation and ion nitriding. It is shown that cast steel, crystallized in a water cooled crystallizer, has a strength not lower than forged or rolled with significantly lower anisotropy properties and accelerated carbon diffusion when cementation. The discovered patterns are caused by the structural and chemical homogeneity of boundary grain volumes, which formation is affected by copper impurities. Uniform density of copper in the said volumes not only reduces their propensity to localize plastic deformation, but contributes to a higher ability for uniform carburization of these steels in the process of cementation. This causes a change in the main characteristics of the cemented layers and is the basis for increasing the bearing capacity of the gearwheels. The obtained results also testify to the fact that controlling grain-boundary effects in steel material at the stage of crystallization of blanks can be a significant factor in increasing the characteristics of the hardened layer in the manufacture of nitrided gearwheels from cast blanks of the electroslag redistribution. A set of studies was carried out and results were obtained which indicate that the control of grain boundary effects in modern steel material at the stage of its crystallization may be a significant factor in improving the characteristics of the hardened layer in the manufacture of cemented and nitrated gear wheels from cast billets electroslag remelting.