Influence of electrolytic-plasma surface quenching on the structure and strength properties of ferritic-pearlite class wheel steel

Abstract

This paper examines the influence of electrolyte-plasma surface hardening on the structure and micro- hardness of wheel steel mark 2. In the work electrolyte-plasma surface quenching was carried out in an electrolyte made from an aqueous solution of 10% carbamide (NH 2 ) 2 CO + 20% sodium carbon- ate Na 2 CO 3 . The work investigated the strength limit, fluidity and wear intensity of the wheeled steel after electrolyte-plasma surface quenching. After electrolytic-plasma surface quenching, a batch, high-temperature plate and low-temperature plate martensit is formed on the surface of the sample. Investigations have been carried out on microhardness determination on cross-section of wheel steel samples after quenching in aqueous solution of electrolyte. It is found that after electrolytic-plasma surface quenching, the microhardening values of this hardened surface layer increased on ≈ 3 times compared to the steel matrix, and the thickness of the hardened layer is 1000-1500 µ m. According to the results of the scanning transmission electron microscopy, the electrolyte-plasma surface quenching caused a change in the morphological constituents of steel mark 2. In the initial state, the matrix of steel is a α -phase, the morphological components of which are fragmented unfragmented ferrite and pearlite.