Effect of heat treatment process on microstructure and dimensional stability of 2A12 aluminum alloy

Influence of heat treatment process of T4, T6 and cryogenic-thermal cycling treatment after solution treating (modified T7) on microstructure, properties and dimensional stability of a 2A12 aluminum alloy was investigated. The results show that compared with the normal heat treatments T6 and T4, the tensile strength, yield strength and microyield strength of the aluminum alloy come a long way by T7, 15% higher than T6, and much more than T4. The microstructure shows that after treated by the thermal cycle test (T7), no significant recovery and recrystallization process are observed in 2A12 aluminum alloys. The grains deflected and the new orientations blocked the dislocation slip. The laves transformed to S' phase entirely. Compared with T6, the mechanical properties and dimensional stability are raised because of the laves under T7 are completely precipitated and uniformly distributed. The dimensional stability tested results show that the dimensional stability of 2A12 aluminum alloy treated by T7 is 30% higher than T4.