誘導加熱装置による高温短時間溶体化処理がAC4CH合金の機械的性質に及ぼす影響

抄録

  The effects of microstructure changes by short time solution treatment at high temperatures using a high-frequency induction heating apparatus on mechanical properties in an AC4CH aluminum alloy were investigated. In the sample solution treated at 560℃ for 3min with heating rate of 40℃/s, Vickers hardness in the primary α-aluminum phases and 0.2% proof stress increased by 21% and by 23% respectively as compared with those of the as-cast condition. The increase in hardness and proof stress was in good agreement with Mg and Si concentrations in the primary α-aluminum phases. These mutual relationships suggest that the solid solution hardening is acting effectively. In addition, it is also suggested that formation of the cluster during natural aging has a small influence. For samples which were solution-treated at 560℃ for 3min or more, the work hardening exponent (n value) increased with the increase in strain during the tensile test. The increase in the n value is thought to be due to the change in the dislocation structure caused by the solution of Mg and Si atoms into the α-aluminum phases. Distributions of eutectic Si particles and dimples in the fracture surface suggest that the slight increase of fracture elongation for solution treated at 560℃ beyond 3min was caused by the increase of inter particle distance between the eutectic Si particles.