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<p>Inconel 718 fabricated by powder bed fusion-laser beam (PBF-LB) requires heat treatment to enhance its microstructure and mechanical properties for critical applications. The standard heat-treatment conditions enhance the properties of as-printed IN718 but require optimization for PBF-LB parts. Achieving a uniform microstructure, improved strength, and enhanced crack resistance under demanding conditions remains a challenge. This study investigates the effects of different heat treatments, including homogenization heat treatment (HHT), solution heat treatment (SHT), and two-step aging heat treatment (AHT), on the microstructure, microhardness, and wear behavior of PBF-LB Inconel 718. HHT was conducted at 1080&#xa0;°C for 1-8&#xa0;h, followed by SHT at temperatures ranging from 980 to 1140&#xa0;°C for 1&#xa0;h, and AHT at 760&#xa0;°C and 650&#xa0;°C. The results indicate that the initial grain morphology and Laves phase remained largely unchanged after 1-2&#xa0;h of HHT at 1080&#xa0;°C. However, a 4-hour HHT resulted in full recrystallization and significant dissolution of the Laves phase. Extending the HHT to 8&#xa0;h led to grain growth and the enlargement of carbide precipitates. After heat treatment, microhardness increased by 56%-77.39%, while the friction coefficient decreased by up to 22% compared to the as-built condition, which was attributed to the formation of <i>γ</i>′ and <i>γ</i>″ phases within the <i>γ</i>-matrix. These results emphasize the critical role of optimizing heat-treatment duration to achieve the desired balance of mechanical properties and microstructural stability, thereby demonstrating the potential of PBF-LB fabricated Inconel 718 for high-performance applications.</p>

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Influence of Modified Heat Treatment on Microstructure, Hardness and Wear Resistance of Inconel 718 Fabricated by Powder Bed Fusion-Laser Beam Additive Manufacturing Process

  • 期刊论文

  • 发表日期：

    2025年5月5日

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  • Aman Dwivedi,
  • Manoj Kumar Khurana,
  • Y. G. Bala,
  • Suryanarayan B. Mishra

摘要

Inconel 718 fabricated by powder bed fusion-laser beam (PBF-LB) requires heat treatment to enhance its microstructure and mechanical properties for critical applications. The standard heat-treatment conditions enhance the properties of as-printed IN718 but require optimization for PBF-LB parts. Achieving a uniform microstructure, improved strength, and enhanced crack resistance under demanding conditions remains a challenge. This study investigates the effects of different heat treatments, including homogenization heat treatment (HHT), solution heat treatment (SHT), and two-step aging heat treatment (AHT), on the microstructure, microhardness, and wear behavior of PBF-LB Inconel 718. HHT was conducted at 1080 °C for 1-8 h, followed by SHT at temperatures ranging from 980 to 1140 °C for 1 h, and AHT at 760 °C and 650 °C. The results indicate that the initial grain morphology and Laves phase remained largely unchanged after 1-2 h of HHT at 1080 °C. However, a 4-hour HHT resulted in full recrystallization and significant dissolution of the Laves phase. Extending the HHT to 8 h led to grain growth and the enlargement of carbide precipitates. After heat treatment, microhardness increased by 56%-77.39%, while the friction coefficient decreased by up to 22% compared to the as-built condition, which was attributed to the formation of γ′ and γ″ phases within the γ-matrix. These results emphasize the critical role of optimizing heat-treatment duration to achieve the desired balance of mechanical properties and microstructural stability, thereby demonstrating the potential of PBF-LB fabricated Inconel 718 for high-performance applications.