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Laser Hardfacing of Colmonoy-5 (Ni-Cr-Si-B-C) Powder onto 316LN Austenitic Stainless Steel: Effect of Powder Feed Rate on Microstructure, Mechanical Properties and Tribological Behavior
S. Gnanasekaran, G. Padmanaban, V. Balasubramanian, H. Kumar and S.K. Albert

Laser hardfacing is a method whereby another layer of material is deposited onto a substrate by laser fusion of blown powders or pre-placed powder deposit. Multiple layers can be saved to form shapes with complex geometry. This manufacturing procedure has been utilized for modifying the material surface property and for the repair of the component. There are many parameters which have influence on controlling the characteristics of laser hardfaced surfaces and one such parameter is powder feed rate. In this investigation the effect of powder feed rate on microstructure, microhardness and wear resistance of laser hardfacing Ni-based Colmonoy-5 alloy (Ni-Cr-Si-B-C) powder onto a 316LN austenitic stainless steel substrate was analysed. The powder feed rate was varied from 3 to 11 g/min. The other parameters such as laser power, travel speed and defocusing distance were kept constant. From this investigation, it was found that the deposit hardness increased from 500 to 800 HV with increase in powder feed rate. The microstructure of the hardfaced deposit primarily consists of the γ-Ni phase and the interdendritic eutectic mixture comprises γ-nickel, nickel-rich borides and chromium-rich carbides. These contribute to higher hardness in deposits at higher powder feed rate.

Keywords: Disc laser, 316LN austenitic stainless steel, Colmonoy 5, Ni-Cr-Si- B-C, nickel-based powder, laser hardfacing, powder feed rate, microstructure, hardness, wear

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