AZ31Bマグネシウム合金の半溶融状態での固相の球状化に及ぼす熱処理と加工の影響

抄録

  The structural changes of AZ31B in the semisolid state are clarified in terms of the responses of AZ31B to a certain heat treatment temperature, holding time, heating rate and deformation rate. Two types of test piece are adopted, namely, the heat-extruded material without predeformation and that with predeformation, resulting in a 30% height reduction at 573 K(300°C). The following are the main results. (1) The heat-extruded material without predeformation only exhibits grain growth after a long holding time. (2) The heat-extruded material with 30% predeformation shows an almost perfectly spheroidized structure in the semisolid state at a temperature of 883K, heating rate of 2 K•s^-1 and holding time of 120 s. (3) The heating rate markedly affects the spheroidizing rate of grains. In the case of the heating rate is larger than the diffusion rate at a semisolid temperature, it is difficult to obtain the spheroidized semisolid structure.