Al-Mg合金の引張性質に及ぼすMnとCrの影響
1974 年 23 巻 251 号 p. 619-625
詳細
1974 年 23 巻 251 号 p. 619-625
The effects of Mn and Cr on tensile properties of Al-Mg alloys were investigated by the tensile test performed in the temperature range from room temperature to 400°C. The compositional ranges of the test alloys were Mg=0-5%. Mn=0-1.0% and Cr=0-0.5%, respectively. Specimens were preannealed at 450°C for 1hr to bring them up close to the steady state at high temperatures, and then heated up to the test temperature and held for 30min.
The results obtained are as follows:
(1) The strength of alloy at relatively low temperatures depends largely on Mg content and increases with increasing its content. On the other hand, Mn and Cr have little effects, increasing slightly the strength but decreasing the elongation with the increase of their contents.
(2) It would be satisfactory to consider that the strength of alloy at relatively low temperatures is primarily caused by the effect of Mg dissolved in Al, which improves the solid solution hardenability and work hardenability.
(3) With rising temperature, the contributions of Mn and Cr on the strength gradually increase but that of Mg decrease, on the contrary. The strength of alloy, therefore, turns out to be dependent on Mn or Cr content rather than on Mg.
(4) The behavior at relatively high temperatures is caused by disappearance of the effect induced by the dissolved Mg on account of the expansion of crystal lattice and of the high diffusion rate of Mg in Al. It is also caused by the contribution of Mn and Cr on the maintenance of strength owing to the small diffusion rates of these elements and the derivative effect of delayed recrystallization.
