Hardening technology of metallurgical equipment parts by high-speed nitrogen alloys

Abstract

The technology for hardening of metallurgical equipment parts by high-speed alloys with high nitrogen content is developed. The manufacturing process of deposited parts includes: machining of the workpiece, plasma surfacing, high-temperature tempering, finishing machining and quality control. To form a coating on 30KhGSA steel, an installation for plasma surfacing of bodies of rotation is used. A method and surfacing materials for multilayer plasma surfacing are developed, which make it possible to obtain deposited layers made of high-speed alloys (type R18Yu), additionally alloyed with nitride ferrochrome and titanium, which allows increasing the nitrogen content from 0.02 to 0.12 %. The surfacing method with low-temperature heating and surfacing materials prevent the formation of cracks during the surfacing process and ensure the hardness of the deposited metal up to 59...60 HRC without additional heat treatment. The hardness of the deposited metal after high-temperature tempering at a temperature of 560...580 °C increases to 62...64 HRC. Multilayer plasma surfacing made it possible to obtain a high-quality surfaced layer without cracks, pores and microstructure defects. The main phases of the deposited layer are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium. The wear resistance of the deposited parts of metallurgical equipment (rolls and rollers of crushers) increases by 1.5—2.0 times.