Determination of the optimum conditions for ion nitriding of 32CDV13 low alloy steel

Abstract

The excellent mechanical properties of chrome-vanadium low alloy steel usually obviate the need for expensive quench and tempering operations. Furthermore, the presence of a significant amount of nitride phases has generated interest in the applicability of this kind of steel to fabricate tools with good corrosion and wear resistance. In this paper, 32CDV13 low alloy steel was ion nitrided under different process parameters including time (2, 4, 6 and 8 h), temperature (380, 500 and 580 8C) and gas mixture (N2, H2 and CH4). By determining phase composition, hardness profiles, compound layer thickness and case depth, the optimum working conditions were determined. Microhardness tester, X-ray diffraction and scanning electron microscopy were utilised to characterise the nitrided surfaces. The observed differences in the hardness, the thickness and the structure of the compound layers and the diffusion zones are discussed. The optimum results were obtained at 75%N2þ20%H2þ5%CH4 gas mixture, at the temperature of 500 8C and for a process time of 8 h.