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<p>Invar alloys are extensively used in aerospace, mold manufacturing, and precision structural applications due to low coefficient of thermal expansion. However, developing Invar alloys with high hardness, strength, and wear resistance is challenging. Surface grain refinement is an efficient method to meet this challenge while maintaining the precision structure of the mold. In this study, ultrafine-grained surfaces of Invar alloy are prepared via ultrasonic surface rolling process (USRP) and laser heat treatment-assisted USRP (LHT-USRP). The grain refinement evolution mechanism and wear resistance of USRP and LHT-USRP are investigated. The results show that submicron ultrafine grains can be produced on the surface of Invar alloy via USRP, driven by dislocation motion and the stacking fault mechanism. LHT before USRP increases the proportion of low angle grain boundaries, accelerates grain refinement, and deepens the plastic deformation layer by 18%. Compared to untreated samples, the surface hardness of USRP- and LHT-USRP-treated samples increases by 48.8% and 52.2%, while the wear rate decreases by 26.5% and 58.8%, respectively. These improvements are attributed to increased surface hardness, grain refinement, and residual compressive stress, which enhance surface performance and friction-wear properties. This study highlights the potential of LHT-USRP in enhancing the surface performance of Invar alloys.</p>

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Microstructure and wear behavior of ultrafine-grained surfaces in Invar alloy prepared by laser heat treatment and ultrasonic surface rolling

  • 期刊论文

  • 发表日期：

    2026年3月19日

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  • Ting-xia Luo,
  • Ya-li Chen,
  • Tao Cheng,
  • Meng Nie,
  • Cun-hong Yin,
  • Xiong-feng Hu,
  • Bo Lin,
  • Hua-qiang Xiao,
  • Zheng-wen Zhang

摘要

Invar alloys are extensively used in aerospace, mold manufacturing, and precision structural applications due to low coefficient of thermal expansion. However, developing Invar alloys with high hardness, strength, and wear resistance is challenging. Surface grain refinement is an efficient method to meet this challenge while maintaining the precision structure of the mold. In this study, ultrafine-grained surfaces of Invar alloy are prepared via ultrasonic surface rolling process (USRP) and laser heat treatment-assisted USRP (LHT-USRP). The grain refinement evolution mechanism and wear resistance of USRP and LHT-USRP are investigated. The results show that submicron ultrafine grains can be produced on the surface of Invar alloy via USRP, driven by dislocation motion and the stacking fault mechanism. LHT before USRP increases the proportion of low angle grain boundaries, accelerates grain refinement, and deepens the plastic deformation layer by 18%. Compared to untreated samples, the surface hardness of USRP- and LHT-USRP-treated samples increases by 48.8% and 52.2%, while the wear rate decreases by 26.5% and 58.8%, respectively. These improvements are attributed to increased surface hardness, grain refinement, and residual compressive stress, which enhance surface performance and friction-wear properties. This study highlights the potential of LHT-USRP in enhancing the surface performance of Invar alloys.