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<p>The recycling and reuse of superalloy scrap constitutes a critical approach to reducing engine component costs, necessitating guaranteed material performance. This study investigates the effects of recycled processing scrap on the cleanliness, microstructure, and mechanical properties of GH4738 nickel-based superalloy through vacuum induction melting (VIM) combined with vacuum arc remelting (VAR). Results demonstrate that, compared with the 100% virgin alloy, the 60% scrap-containing alloy showed an 83% increase in total impurity content, from 29 ppm to 53 ppm, and an 8-fold increase in inclusion count per unit area, from 2.64/mm<sup>2</sup> to 21.04/mm<sup>2</sup>. The incorporation of recycled scrap does not induce significant alterations to the alloy’s macrostructure but does substantially increases carbide precipitation and exacerbated intergranular segregation of carbides along grain boundaries. Although tensile properties remain comparable, 60% scrap-containing alloy exhibits a 53% reduction in stress rupture life at 730°C/550&#xa0;MPa accompanied by 24% lower elongation. Fracture analysis reveals that it contains more defects with significant microvoid accumulation at MC carbide interfaces, serving as the dominant factor responsible for its degraded stress rupture performance. Optimizing impurity removal efficiency while suppressing inclusion clustering and carbide segregation is the critical metallurgical principle for achieving sustainable superalloy production through scrap recycling.</p>

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Recycling of Superalloy Scrap Through VIM-VAR: Cleanliness, Microstructure, Mechanical Properties

  • 期刊论文

  • 发表日期：

    2026年5月8日

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  • Yu Gu,
  • Peng Zhao,
  • Xiwei Wang,
  • Qiqi Wu,
  • Shufeng Yang,
  • Shulei Yang

摘要

The recycling and reuse of superalloy scrap constitutes a critical approach to reducing engine component costs, necessitating guaranteed material performance. This study investigates the effects of recycled processing scrap on the cleanliness, microstructure, and mechanical properties of GH4738 nickel-based superalloy through vacuum induction melting (VIM) combined with vacuum arc remelting (VAR). Results demonstrate that, compared with the 100% virgin alloy, the 60% scrap-containing alloy showed an 83% increase in total impurity content, from 29 ppm to 53 ppm, and an 8-fold increase in inclusion count per unit area, from 2.64/mm2 to 21.04/mm2. The incorporation of recycled scrap does not induce significant alterations to the alloy’s macrostructure but does substantially increases carbide precipitation and exacerbated intergranular segregation of carbides along grain boundaries. Although tensile properties remain comparable, 60% scrap-containing alloy exhibits a 53% reduction in stress rupture life at 730°C/550 MPa accompanied by 24% lower elongation. Fracture analysis reveals that it contains more defects with significant microvoid accumulation at MC carbide interfaces, serving as the dominant factor responsible for its degraded stress rupture performance. Optimizing impurity removal efficiency while suppressing inclusion clustering and carbide segregation is the critical metallurgical principle for achieving sustainable superalloy production through scrap recycling.