Planning experiments for heat treatment of products from powder steels in electrolytes

Abstract

The studies used quenching in electrolyte, determined the content of carbon and alloying elements, strength, toughness, hardness, microhardness of structural components, as well as metallographic analysis, X-ray diffraction and X-ray phase analysis. Samples and parts made of powder steels were used as the materials under study. The material in the manufacture of which were powders of the following brands: SP100, SP150, SP150D1,5, SP 100D2,5, SP100N1X1. The porosity of the studied samples ranged from 15 to 20 %. To increase the wear resistance, only the working surface of the part was quenched in electrolyte. By changing the current strength and density, only the surface of the sleeve can be hardened. When an electric current is passed, a rapid heating of the sample occurs, when the current is turned off after heating, the sample is cooled in the same electrolyte. After the heat treatment of the products (bushings), the determination of mechanical properties (bending strength) was carried out in accordance with GOST 26529–85. The test samples have the shape of a hollow cylinder. The sample is destroyed by compression and the maximum load preceding its destruction (σr.s.) is determined on the scale of the testing machine (the maximum stress that occurs at the moment of destruction or the appearance of a crack in it). The bending strength of powder steels was determined using a universal testing machine IR 5047-50 with a measurement error of ± 1 %. Microhardness was measured using a PMT-3 microhardness meter. The hardness was determined by the Brinell method on the installation of the WEB308/111 brand. Tensile and compression tests were carried out in special equipment on the UMM-5 breaking machine. The analysis of the mathematical model of heat treatment in electrolytes is carried out on the example of the regression equation of hardening of steel SP100D2.5H3-1 in NaCl solution.