Duplex surface treatment on microalloy steels by dehydrated paste pack boriding and pack carburizing

Abstract

In this work, a novel duplex surface treatment is carried out on API X60 microalloy steels by boronizing and carburizing. Firstly, the dehydrated paste pack boriding (DPPB) on microalloy steels was carried out at a temperature of 1273 K for 8 h of exposure time. Then, the pack carburizing (PC) was conducted on borided steels at 1173 K temperature for four different exposure times. The layers formed by DPBP and DPBP+PC, were caracterized by X-ray difrraction, scanning electron microscopy, and energy dispersive spectroscopy. The results show that DPBP+PC promotes the formation of coatings outermost cementite layer with a range of depth (15.30–45.34 µm) over the boride layer. Hardness and Young's modulus of DPPB+PC were measured using the nanoindenter with a Berkovich diamond tip under load of 100mN. The higher average indentation hardness (HIT=1.53±0.25 GPa) and Young's modulus (EIT=212.70±2.4 GPa) were characteristic of carburized layer as well as Fe2B layer was characterized by HIT=20.56±0.80 GPa, and EIT=300.9±15.57 GPa, these parameters have an important influence on wear resistance to improve the performance in practical applications.