Grain growth in ultrafine grain sized copper during cyclic deformation

• Published in: Journal of alloys and compounds Vol. 615; pp. S587 - S589
• Main Authors: Han, Seung Zeon, Goto, Masahiro, Ahn, Jee-Hyuk, Lim, Sung Hwan, Kim, Sangshik, Lee, Jehyun
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Kidlington Elsevier B.V 05-12-2014; Elsevier
• Subjects: Alloys; ANNEALING PROCESSES; Coarsening; Cold working, work hardening; annealing, quenching, tempering, recovery, and recrystallization; textures; Condensed matter: structure, mechanical and thermal properties; Copper; COPPER (PURE); Cross-disciplinary physics: materials science; rheology; Damage accumulation; DEFORMATION; Dynamic recrystallization; ECAP; Equal channel angular pressing; Exact sciences and technology; FAILURE; Fatigue failure; Fatigue limit; Fatigue strength; Fatigue, brittleness, fracture, and cracks; GRAIN GROWTH; GRAIN SIZE AND SHAPE; Grains; Materials science; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; MICROSTRUCTURES; Nano-grain; Nanostructure; Other heat and thermomechanical treatments; Physics; REFINING; TENSILE STRENGTH; Treatment of materials and its effects on microstructure and properties; Copper; Nano-grain; Dynamic recrystallization; Fatigue strength; ECAP; Grain size; Annealing; Grain growth; Cyclic loads; Fatigue limit; Tensile strength; Nanometer scale; Fine grain structure; Damage; Microstructure; Grain refinement
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.12.004

•Nano-grain copper has extraordinary low fatigue limit contrary to its high tensile strength.•Discovery of grain growth on the surface during fatigue experiment at room temperature.•Observation of dynamic grain growth in the nano-grained copper during cyclic stress (cyclic deformation) at room temperature.
The nano-sized grain microstructure of pure copper was achieved by Equal Channel Angular Pressing (ECAP) in which the average grain size of 4 and 8 passed ECAP was about 320 and 300nm. The grain refining increased the tensile strength of ECAPed copper to 420MPa from 210MPa of annealed counterpart. Despite the increase in strength level, the nano-grained copper fabricated by ECAP process did not show the expected level of fatigue strength, such that the fatigue limit was similar to that of coarse grained copper at low applied stress range. In this study, the damage accumulation during fatigue was found to be accelerated in ultrafine grained copper compared to coarse grained counterpart. The damage accumulation mechanism in ultrafine grained copper was discussed based on the micrographic observation.