<p>This study explores the impact of grain size and specimen size on the mechanical properties of Al99.8 strips. Seven grain sizes (100 to 2500 µm) and five specimen widths (2 to 6 mm) were created and investigated, monitoring six mechanical properties via tensile tests. It was determined that the preliminary cold forming allows desired adjustment of grain size. Yield strength analysis using the Hall-Petch relation revealed a poor fit (R<sup>2</sup> = 0.60) but confirmed that smaller specimen sizes with fewer grains show decreased yield strength, reducing from 25.5 to 21 MPa (17.6 % reduction). Ultimate tensile strength (UTS) exhibits a strong dependence on grain size (R<sup>2</sup> = 0.95) but also varies with specimen size, decreased by 13.2 % from 63 to 54.7 MPa with fewer grains and by 24 % compared to bulk material. Elongation at UTS shows an unusual increase for grains above 1500 µm, while elongation at break and displacement during necking demonstrate size-dependent variations.</p>

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Investigating the influence of grain and specimen size on the mechanical properties of coarse grain tensile specimens

  • Dorottya Varga,
  • Attila Szlancsik

摘要

This study explores the impact of grain size and specimen size on the mechanical properties of Al99.8 strips. Seven grain sizes (100 to 2500 µm) and five specimen widths (2 to 6 mm) were created and investigated, monitoring six mechanical properties via tensile tests. It was determined that the preliminary cold forming allows desired adjustment of grain size. Yield strength analysis using the Hall-Petch relation revealed a poor fit (R2 = 0.60) but confirmed that smaller specimen sizes with fewer grains show decreased yield strength, reducing from 25.5 to 21 MPa (17.6 % reduction). Ultimate tensile strength (UTS) exhibits a strong dependence on grain size (R2 = 0.95) but also varies with specimen size, decreased by 13.2 % from 63 to 54.7 MPa with fewer grains and by 24 % compared to bulk material. Elongation at UTS shows an unusual increase for grains above 1500 µm, while elongation at break and displacement during necking demonstrate size-dependent variations.