Interrupted hot torsion at 450 degree C have been performed on as-cast specimens Al-4. 85 pct Mg-0. 74 pct Mn-0. 22 pct Cr homogenized by three different heating schedules. The tests lead to the finding that minor Si impurity, as little as 0. 05 pct, is harmful to hot ductility. Fe impurity up to 0. 34 pct has no influence. Preheating at 430 degree C for one and a half hours plus soaking at 530 degree C for eight hours results in the best hot ductility. Three different kinds of interdendritic precipitates (Fe, Mn)Al//x, (Cr,Mn,Fe,Ti)Al//7, and Mg//2Si have been identified by electron microscopy. After homogenization, submicron dispersoids of MnAl//6, containing Fe and Cr as alloying elements, precipitate within the dendrites and exert major influences on hot ductility.
|Number of pages||9|
|Journal||Metallurgical transactions. A, Physical metallurgy and materials science|
|State||Published - 1986|