Effect of Ni additions on microstructure, interfacial diffusion behavior and properties of Fe-based/B4C composite coating by vacuum cladding

Abstract

In order to improve the hardenability and toughness of Fe-based/B 4 C composite coatings, which were bonded on ASTM 1045 steel by vacuum cladding, nNi ( n = 0, 1, 3, 5, weight %) were added into the coatings. The influences of Ni additions on the microstructures, interfacial diffusion behavior, impact toughness and three-body abrasive wear behavior of composite coatings were investigated systematically. The results indicated that coatings were completely fused with steel substrate without micro-defects. When the amount of Ni was increased, the activity of the C atom on the coating side was enhanced, the decarburization zone near the interface disappeared, and the metallurgical bonding state of interface was strengthened. Furthermore, the increment of Ni improved the hardenability of coating and promoted the transformation from pearlite to martensite in the matrix structure of the coating. The impact toughness of the coating samples also increased with the increment of Ni additions, and reached the maximum of 4.8 J/cm 2 at 5Ni sample. The three-body abrasive wear test implied that when 3 wt% Ni was added to the coating, the mass loss was 0.14 g, which was much lower than that of other samples and exhibited the best wear resistance. The wear mechanism of coatings changed from partial plastic cutting and fatigue spalling to single fatigue spalling. • Ni addition strengthens the metallurgical bonding state of the coating interface. • The increase of Ni addition improves the hardenability of the coating matrix. • Ni addition improves the impact toughness and wear resistance of the coating.