Study On The Wear Resistance And Anticorrosion For QPQ Complex Salt Bath Treatment Technology Of3Cr2W8V Hot-Working Die Steel

QPQ complex salt bath treatment is a new modification of surface hardening of metal salt bath. As prefix stands for the "Quench-Polish-Quench","QPQ" is salt bath Nitrocarburizing and oxidation-polishing-the second oxidation process of the composite; metal is made for combined treatment in two different kinds of low-temperature molten salt bath, in order to penetrate the metal surface with a variety of elements to form compounds formed by several complex layer to be strengthened so that the metal surfaces are modified, while the whole process can be harmless, which is complex salt bath treatment technology.As a veteran strong heat hot work die steel,3Cr2W8V is widely used in die casting dies, extrusion mold, forging mold with good forging process performance and machining process performance and heat treatment process performance. High temperature wear is a hot die failure of a major form, so domestic and foreign scholars have done a lot of work in high temperature wear behavior research, but a little research in3Cr2W8V steel in high temperature wear properties, so the research of QPQ technology for high-temperature steel3Cr2W8V Wear behavior is less.This article uses the oxygen sensor to measure potential of oxygen at different temperatures in carbonitriding salt bath and oxidation salt bath. According to the Nernst equation, partial pressure of oxygen is calculated, so as to establish the quantitative relationship between the oxygen potential, oxygen pressure and temperature. This thesis systematically studies QPQ technology factors influencing the macro morphology, microstructure, phase composition, microhardness, high temperature wear behavior and corrosion resistance of3Cr2W8V steel and explores the mechanisms of anti-corrosion wear to improve the steel hot die3Cr2W8V life. Analysis shows the following conclusions:(1) In the salt bath nitrocarburizing temperature range, oxygen potential and the partial pressure of oxygen along with the temperature then decreased, showing openings down the parabolic shape; in the salt bath oxidation temperature range, oxygen potential decreasing with increasing temperature after the first increment, showing upward opening parabola shape, oxygen partial pressure decreasing with increasing temperature after the first flat.(2) When the salt bath nitrocarburizing time is certain, with the increasing of salt bath nitrocarburizing temperature, the first appeared phase is Fe3N, followed by the emergence is Fe4N and Fe3O4phase, and finally there Fe2N phase. QPQ treated specimen surface hardness is600HV-1400HV. The wear volume of QPQ treatment samples is only the half of the matrix, with the minimum friction coefficient. In the same oxidation salt bath temperature, with the increasing oxidation time, the corrosion potential gradually increased, and the corrosion resistance increases gradually; when the molten salt oxidation temperature parameter is set to380℃and the oxidation time is set to120min, QPQ treatment sample by trial has the. highest corrosion potential and corrosion resistance of the best.