Influence of tungsten on microstructure and wear resistance of iron base hardfacing alloy

Abstract

A series of iron based hardfacing alloys with varying tungsten contents were fabricated using slag free self-shielded flux cored wire, and the effects of tungsten addition on microstructure and wear performance were investigated. The experimental results showed that the iron base tungsten free hardfacing alloy has a typical hypereutectic microstructure, which consists of primary hexagonal M₇(C, B)₃ carbides and eutectic long bar-like M₃(C, B) carbides in the austenite and martensite matrix. The addition of tungsten increases the size of primary hexagonal M₇(C, B)₃ carbides and promotes the formation of martensite, as well as changes the morphology of eutectic carbides. It was found that the eutectic carbides change from the long bar-like shape to the scattered web shape with the increase in tungsten content to 9 wt-%, and subsequently change to the plate shape with further increasing the tungsten content to 12 wt-%. For the all tungsten containing hardfacing alloys, tungsten exists in both the carbides and matrix uniformly. Results also showed that the wear loss of the sample with 9 wt-% tungsten was the smallest among all the samples owing to the higher hardness and reinforced microstructure.

Keywords:

• Tungsten addition
• Iron base
• Hardfacing
• Self-shielded flux cored wire
• Microstructure
• Wear resistance