Laser Surface Alloying (LSA) of AISI 304 Stainless Steel with 20WC+40Co+40NiCr for Improving Wear Resistance
A. Chakraborty, I. Manna, D. Sen, S. Pityana, T. Dutta and J. Dutta Majumdar
Laser surface alloying (LSA) of AISI 304 stainless steel with WC+Co+NiCr in the weight ratio of 20:40:40 has been carried out with a 5 kW continuous wave (CW) Nd:YAG laser by melting the surface with laser and simultaneous feeding the powder mixture using Ar as shrouding environment. The main process variables in the present study were applied laser power and scan speed. Followed by LSA, a detailed characterization of the alloyed zone was carried out in terms of surface roughness, microstructure, composition, and phases present. The wear resistance property was evaluated by fretting wear testing unit against WC ball. There is a significant improvement in hardness due to LSA (310 to 320 VHN) as compared to 245 VHN of the as-received AISI 304 stainless steel substrate. The wear resistance property was also found to be improved due to mainly grain refinement, precipitation refinement and supersaturation of Cr and Ni in the matrix. The mechanism of wear resistance improvement has been discussed.
Keywords: Nd:YAG laser, AISI 304 stainless steel, WC+Co+NiCr, laser surface alloying (LSA), powder, microhardness, wear, residual stress