PLASMA MODIFICATION OF STRUCTURE OF REPLACEMENT OPERATING PARTS OF FARM VEHICLES

Abstract

On the basis of own researches and the analysis of references it has been shown that for extension of an operational resource of heavy-duty high-wear parts in parameters of universality, availability and economic efficiency surface plasma tempering is rational. Without changing surface roughness parameters, such strengthening heat treatment easily is built in technology process of recovery of parts, is finishing operation. It is low-cost, rather productive and allows to improve effectively operational firmness of replacement parts of agricultural machines. By comparison of results of the studied five options of thermal hardening of flat samples from steel 65G it has been proved that the best combination of high strength, plastic and viscous properties for
heavy-duty replacement working parts of soil cutting machines is provided by plasma modification with tempering at 300 0C.
It is confirmed that at the superfast speed of heating taking place at plasma tempering, phase transformations are displaced in area of high temperatures and this thermally activated process strongly influences kinetics of emergence and growth of nuclei of a new phase. The ratio between the speed of origin of austenite and speed of their growth changes; in process of temperature
increase process of origin of austenite happens quicker, than acceleration of their growth, and is observed the increasing quantitative advancing of speed of origin over growth rate. It leads to forming of fine-grained austenite which it turns high-disperse martensite with high strength characteristics.