Microstructure and Wear Resistance Enhancement of H13 Hot Worked Tool Steel by Means of Laser Clad NiCrBSi+Wc Powder
C-J. Chen, X. Xu, Q. Cao, M. Zhang, S-C. Zhang and Q-M. Chang
In the present work a self-fluxing NiCrBSi+Wc powder was laser clad onto a H13 hot worked tool steel. The purpose of the experiment was to enhance the wear resistance of the H13 steel. The results show that up to 0.9 mm thick, fully dense and crack-free NiCrBSi+Wc laser clad layers could be formed on the H13 steel substrates. The microstructure of the clad coating was analysed by scanning electron microscope (SEM) with attached energy dispersive X-ray analysis (EDX). The microhardness of the clad layers was measured using a Vickers microhardness tester. Wear behaviour was determined by using block-on-ring sliding linear contact at 133.5 N loads and sliding speeds 0.65 m/s. It was found that no pores and crack-free clad layers could be obtained, with measured hardness ranging from 732 to 874 Hv. Higher concentration of precipitates were observed in the overlapped clad tracks. The clad layer wear resistance was a factor of 2 to 3 times higher than that of the unclad H13 tool steel. The wear mechanisms are discussed.
Keywords: Laser cladding, CO2 laser, hot worked tool steel, H13, NiCrBSi, WC, hardness, wear