Preparation and Microstructural Characterization of a High-Cr White Cast Iron Reinforced with WC Particles.

Aida B Moreira,Laura M M Ribeiro,Ana M P Pinto,Pedro Lacerda,Ricardo O Sousa,Manuel F Vieira

doi:10.3390/ma13112596

Abstract

High-chromium white cast iron (WCI) specimens locally reinforced with WC–metal matrix composites were produced via an ex situ technique: powder mixtures of WC and Fe cold-pressed in a pre-form were inserted in the mold cavity before pouring the base metal. The microstructure of the resulting reinforcement is a matrix of martensite (α’) and austenite (γ) with WC particles evenly distributed and (Fe,W,Cr)6C carbides that are formed from the reaction between the molten metal and the inserted pre-form. The (Fe,W,Cr)6C precipitation leads to the hypoeutectic solidification of the matrix and the final microstructure consists of martensite, formed from primary austenite during cooling and eutectic constituent with (Fe,Cr)7C3 and (Fe,W,Cr)6C carbides. The presence of a reaction zone with 200 µm of thickness, between the base metal and the composite should guarantee a strong bonding between these two zones.

Highlights

IntroductionThe addition of further alloying elements, such as molybdenum, nickel, copper and manganese can significantly affect the microstructure, in what concerns the matrix and type of carbides formed, and the final mechanical properties [1,2,3,4]
High-chromium white cast irons (WCIs) are based on the Fe-Cr-C ternary system
WC–metal matrix matrix composites produced via an ex-situ technique, using powder mixtures of as aa binder

Summary

Introduction

The addition of further alloying elements, such as molybdenum, nickel, copper and manganese can significantly affect the microstructure, in what concerns the matrix and type of carbides formed, and the final mechanical properties [1,2,3,4]. The high-Cr WCIs containing 12–30 wt.% Cr are extensively used in severe wear and corrosion applications due to their excellent wear resistance, ability to withstand moderate impact and relatively low production cost. The as-cast microstructure of hypereutectic high-Cr WCIs presents coarse primary. M7 C3 carbides and a eutectic structure of γ and fine M7 C3 carbides, which are responsible for the excellent abrasion resistance of these alloys [1,2,4,5,6]. The wear behavior of components made of high-Cr WCIs can be more improved by ceramic reinforcement of the surfaces that will be exposed to wear, maintaining the toughness of the bulk

Methods

Results

Conclusion