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<p>This study focuses on the machining performance and recrystallization behavior of two Ni-base single-crystal superalloys (NSX alloys) — second-generation DD98 and third-generation DD90N — during high-speed grinding with and without ultrasonic vibration (US) using CBN grinding wheels. Experimental results indicate that DD90N exhibits approximately 18% higher grinding force and temperature on average compared to DD98. For both alloys, the application of US reduces grinding force by up to 20% and temperature by a similar margin. In contrast to conventional grinding, US alleviates tool clogging but aggravates fractures of CBN grains, leading to an approximate 8% increase in surface roughness Ra. Microstructural characterization of the subsurface reveals that ultrasonic-assisted high-speed grinding (UAHSG) induces the formation of nanograins and dislocation structures in NSX alloys. Notably, DD90N features finer recrystallized grains (around 77&#xa0;nm) than DD98 (about 86&#xa0;nm) in the subsurface, primarily due to its significantly higher recrystallization nucleation rate of 1.05 × 10⁶ m⁻²·s⁻¹. Additionally, UAHSG facilitates the formation of recrystallized grains in the subsurface more readily than grinding without US, as the impact effect of abrasive grains under ultrasonic vibration promotes local surface deformation. However, the recrystallized layer is confined to a narrow depth range of 300–500&#xa0;nm, attributed to the reduced grinding temperature induced by US, which inhibits dynamic recrystallization. Consequently, UAHSG proves effective in suppressing subsurface recrystallization and enhancing the machinability of NSX superalloys.</p>

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Machining Performance and Recrystallization Characteristics of Different Ni-base Single-crystal Superalloys in Ultrasonic Assisted High-speed Grinding

  • 期刊论文

  • 发表日期：

    2026年4月30日

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  • Qing Miao,
  • Wenfeng Ding,
  • Tao Chen,
  • Ning Qian,
  • Biao Zhao,
  • Chenwei Dai,
  • Zhen Yin

摘要

This study focuses on the machining performance and recrystallization behavior of two Ni-base single-crystal superalloys (NSX alloys) — second-generation DD98 and third-generation DD90N — during high-speed grinding with and without ultrasonic vibration (US) using CBN grinding wheels. Experimental results indicate that DD90N exhibits approximately 18% higher grinding force and temperature on average compared to DD98. For both alloys, the application of US reduces grinding force by up to 20% and temperature by a similar margin. In contrast to conventional grinding, US alleviates tool clogging but aggravates fractures of CBN grains, leading to an approximate 8% increase in surface roughness Ra. Microstructural characterization of the subsurface reveals that ultrasonic-assisted high-speed grinding (UAHSG) induces the formation of nanograins and dislocation structures in NSX alloys. Notably, DD90N features finer recrystallized grains (around 77 nm) than DD98 (about 86 nm) in the subsurface, primarily due to its significantly higher recrystallization nucleation rate of 1.05 × 10⁶ m⁻²·s⁻¹. Additionally, UAHSG facilitates the formation of recrystallized grains in the subsurface more readily than grinding without US, as the impact effect of abrasive grains under ultrasonic vibration promotes local surface deformation. However, the recrystallized layer is confined to a narrow depth range of 300–500 nm, attributed to the reduced grinding temperature induced by US, which inhibits dynamic recrystallization. Consequently, UAHSG proves effective in suppressing subsurface recrystallization and enhancing the machinability of NSX superalloys.