Structure and properties of high-speed R2M9YuAT alloy formed by plasma surfacing in nitrogen with flux-cored wire

Abstract

The structure and properties of the high-speed R2M9YuAT alloy formed by plasma surfacing in nitrogen are studied. The samples are surfaced by a plasma arc at reverse polarity with the supply of non-current-carrying filler flux-cored PP-R2M9YuAT wire, additionally containing nitrided ferrochrome and titanium, into the weld pool. Surfacing of the samples is carried out using a plasma surfacing installation using UD-417D flux-cored wires. After surfacing is completed, the workpiece is cooled in air and subjected to high-temperature tempering at a temperature 560...580 °C, holding time 1 hour, number of temperings 4. The microhardness distribution of the surface layer of the deposited R2M9YuAT alloy in the state after plasma surfacing and after surfacing and high-temperature tempering is studied. Microhardness values vary from a minimum value of 4.68 to 5.93 GPa, and the distribution of microhardness of the deposited layer in the state after plasma surfacing is characterized by significant unevenness, which is explained by the comрlex thermal effect of multilayer plasma surfacing. Quadruple hightemperature tempering leads to the transformation of retained austenite and the precipitation of carbides and carbonitrides. The microhardness of the deposited metal after tempering increases from 6.89 to 7.48 GPa, and its distribution has become more uniform. It is established that the main phases in the deposited metal after high-temperature tempering are a solid solution of α-iron, carbides and carbonitrides based on iron, tungsten, molybdenum, chromium, aluminum and titanium.