Effect of Fe2B boride orientation on abrasion wear resistance of Fe-B cast alloy

Abstract

W ear is one of the most important cost factors during mineral processing, rolling steel, cement production and material handling [1][2][3] . High chromium cast irons and Ni hard cast irons contain many eutectic carbides which have high hardness and excellent wear resistance. They are widely used in the above wear domain [4][5][6] . Because high chromium cast irons contain many alloy elements, such as chromium, nickel and molybdenum, etc., they have higher production cost. Moreover, they also have high brittleness and low toughness. Therefore, the development of a high property and low cost wear-resistant material has an important meaning. The proper boron concentration in a low alloy cast steel can produce high hardness boride and improve the wear resistance [7][8][9][10] , which also reduces the addition Abstract:The microstructures and abrasion wear resistance of directional solidification Fe-B alloy have been investigated using optical microscopy, X-ray diffraction, scanning electron microscopy and laser scanning microscopy. The results show that the microstructure of as-cast Fe-B alloy consists of ferrite, pearlite and eutectic boride. After heat treatment, the microstructure is composed of boride and martensite. The plane which is perpendicular to the boride growth direction possesses the highest hardness. In two-body abrasive wear tests, the silicon carbide abrasive can cut the boride and martensite matrix synchronously, and the wear mechanism is micro cutting mechanism. The worn surface roughness and the wear weight loss both increase with the increasing contact load. Moreover, when the boride growth direction is perpendicular to the worn surface, the highest hardness plane of the boride can effectively oppose abrasion, and the martensite matrix can surround and support borides perfectly. of scarce molybdenum and chromium elements, and therefore decreases the production cost. Previous studies [11,12] showed that the hardness of Fe 2 B and FeB type borides is up to 1,500 and 2,400 HV, respectively, while the hardness of (Cr,Fe) 7 C 3 type carbide is only 1,300-1,500 HV. The investigations [13,14] on abrasion wear resistance of high chromium cast irons discovered that M 7 C 3 carbides have higher microindentation hardness in the transverse direction than in the longitudinal direction, and high chromium cast irons present higher abrasion resistance in the transverse section than in the longitudinal section of the M 7 C 3 carbides. Similarly, it has been reported that the borides (Fe 2 B) in Fe-B alloys also have higher microindentation hardness in the transverse than in the longitudinal direction [15] . However, scores of studies have been performed on the effect of boride orientation on abrasion wear resistance. Therefore, focus of this study is on the microstructures and the effect of boride orientation on wear behaviors of the Fe-B cast alloys under directional solidification conditions.