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<p>AISI 4340 high strength low alloy (HSLA) steels are widely used in critical engineering applications, including expensive heavy-duty shafts and gear assemblies, where localized wear often leads to component rejection. In the present work, a systematic study has been attempted to refurbish AISI 4340 HSLA steel component by rebuilding the damaged area using a laser cladding process. Optimized laser cladding parameters enabled the successful deposition of AISI 4340 alloy powder on the substrate from a used component, resulting in a dense, crack-free clad with strong metallurgical bonding and minimal porosity (~ 0.3%). The as-deposited clad exhibited microstructural and hardness inhomogeneity due to overlapping thermal cycles from subsequent clads. The as-clad condition primarily showed a martensite phase (~ 96.5 wt%), with a minor fraction of retained austenite (~ 3.5 wt%). To address this, a post heat treatment (PHT) at 470&#xa0;°C was employed to minimize the inhomogeneity in the clad microstructure with minimal variation in the substrate properties. The PHT clad sample showed a more homogeneous microstructure with an increased martensitic (~ 99.2 wt%) and reduced retained austenite (~ 0.8 wt%). The key findings reveal that the clad region exhibited a tensile strength of ~ 1333&#xa0;MPa, exceeding that of the original substrate (~ 1205&#xa0;MPa), without compromising ductility. A three-point bend test and pin-disc pull test confirms a strong metallurgical bond at the clad-substrate interface. As the actual application is a bearing contact component, the wear behavior of the clad was evaluated, and the performance was found to be on par with that of the substrate. Overall, this study provides a comprehensive and robust framework for the repair and refurbishment of HSLA steel components using the laser cladding process.</p>

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Refurbishment of High Strength Low Alloy AISI 4340 Steel Component Using Laser Cladding: A Study on Microstructure Evolution and Mechanical Characteristics

  • 期刊论文

  • 发表日期：

    2025年6月30日

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  • Kondababu Kadali,
  • Manish Tak

摘要

AISI 4340 high strength low alloy (HSLA) steels are widely used in critical engineering applications, including expensive heavy-duty shafts and gear assemblies, where localized wear often leads to component rejection. In the present work, a systematic study has been attempted to refurbish AISI 4340 HSLA steel component by rebuilding the damaged area using a laser cladding process. Optimized laser cladding parameters enabled the successful deposition of AISI 4340 alloy powder on the substrate from a used component, resulting in a dense, crack-free clad with strong metallurgical bonding and minimal porosity (~ 0.3%). The as-deposited clad exhibited microstructural and hardness inhomogeneity due to overlapping thermal cycles from subsequent clads. The as-clad condition primarily showed a martensite phase (~ 96.5 wt%), with a minor fraction of retained austenite (~ 3.5 wt%). To address this, a post heat treatment (PHT) at 470 °C was employed to minimize the inhomogeneity in the clad microstructure with minimal variation in the substrate properties. The PHT clad sample showed a more homogeneous microstructure with an increased martensitic (~ 99.2 wt%) and reduced retained austenite (~ 0.8 wt%). The key findings reveal that the clad region exhibited a tensile strength of ~ 1333 MPa, exceeding that of the original substrate (~ 1205 MPa), without compromising ductility. A three-point bend test and pin-disc pull test confirms a strong metallurgical bond at the clad-substrate interface. As the actual application is a bearing contact component, the wear behavior of the clad was evaluated, and the performance was found to be on par with that of the substrate. Overall, this study provides a comprehensive and robust framework for the repair and refurbishment of HSLA steel components using the laser cladding process.