Author ORCID Identifier

https://orcid.org/0000-0002-2701-9305

Date of Award

21-5-2025

Document Type

Thesis

School

School of Mechanical Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.P.Dinesh Babu

Keywords

Laser Cladding, Box-Behnken Design, Optimisation, Microhardness, Response Surface Methodology, Microstructure, Residual stress, Wear, Corrosion, CrNiW, CrNiFeAlZr

Abstract

In this work, laser cladding on H13 steel substrate with two different powder compositions CrNiW and CrNiFeAlZr has been carried out. The laser power, powder feed rate, and scanning speed were varied and the clad dimensions, aspect ratio, and dilution percentage were measured. The microhardness found in the CrNiW clad is 834 ± 20 HV0.5, which is higher than that of the CrNiFeAlZr clad (780 ± 20 HV0.5) as well as the substrate (548 ± 20 HV0.5).

The X-ray Diffraction (XRD) patterns identified the common phase creation of Ni3C and Fe3C for CrNiFeAlZr and CrNiW coatings, while the oxide formation was only noticed in CrNiFeAlZr coatings and the addition of carbon content in the CrNiW clad layer forms WC, Cr23C6, Ni3C, and Fe3C. A response surface methodology with a Box–Behnken design is used in the optimisation process.

The optimal deposition conditions were acquired for corrosion, wear, and residual stress study. Compared to the H13 steel substrate, the cladded samples exhibited significantly lower coefficient of friction and superior wear resistance. Furthermore, increased corrosion resistance was achieved by both clad specimens in a 3.5% NaCl solution.

The clad specimens had a higher Ecorr value than the substrate. In contrast, the icorr value of the clad was lower than base metal. The compressive residual stress that was produced on the surface of clad specimens was caused by the difference in the substrate and surface cooling rates during the cladding process.

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