Pre-hardening water quenching effect on the wear resistance of TiCN coated 4140 steels

Abstract

In this comprehensive study, we investigated the mechanical and wear characteristics of AISI 4140 steel specimens subjected to quench hardening and coated with Titanium Carbo Nitride (TiCN) using the Physical Vapor Deposition (PVD) technique. Our analysis encompassed microstructure characterization, cross-sectional examination of the coating layer, phase analysis, microhardness evaluation, and wear behavior assessment, aiming to discern the combined impact of TiCN coating and pre-hardening treatment. The surface imaging and characterization of the coating layer were conducted employing Energy Dispersive Spectroscopy (EDS) assisted Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. Hardness measurements were performed utilizing a microhardness testing apparatus. Furthermore, wear assessments were executed employing a ball-on-disc tribometer, employing two distinct loads of 20 and 40 N. Results revealed that the pre-hardening process led to a remarkable coating surface hardness of 2473 HV, surpassing the 2230 HV recorded in AISI 4140 steel without pre-hardening. Pre-hardening notably improved coating thickness and hardness, and substantially reduced wear rates, especially when combined with TiCN coating. In conclusion, the combined approach of pre-hardening and TiCN coating emerges as a highly effective strategy for enhancing the mechanical and wear properties of this steel alloy.