Effect of Homogenization Treatment and Microalloying with Mn on the Microstructure and Hot Workability of AA6060 Aluminum Alloys

摘要

The effects of a homogenization treatment and microalloying with Mn on the evolution of the microstructure and hot workability of AA6060 aluminum alloys were investigated. Various homogenization treatments with temperatures ranging from 520 to 610 degrees C and soaking times from 2 to 16 h were conducted. The results revealed that beta-AlFeSi intermetallic was the dominant phase in the as-cast microstructure of the experimental alloys. During the homogenization, the fragmentation of intermetallics occurred and plate-like beta-AlFeSi transformed into rod-like alpha-AlFeSi. In addition, a number of dispersoids precipitated in the 0.1Mn alloy in the temperature range of 520-580 degrees C. The flow stress behavior of the homogenized AA6060 alloys was mainly determined by the solid solution level. Increasing homogenization temperatures resulted in higher flow stresses owing to the increase in solute atoms in the aluminum matrix. The incremental Mn addition from 0 to 0.1% moderately increased the flow stress by up to 3%. Grain growth occurred in the alloys with low Mn contents (< 0.03Mn) during the high-temperature homogenization (580-610 degrees C), which resulted in a sudden decrease in the flow stresses and an irregular sample shape after the deformation. Microalloying with Mn (> 0.06%) can effectively prevent grain growth at such temperatures. For an alloy with Mn (0.1%) microalloying, homogenization at 550-580 degrees C for 6 h could be the optimal condition to balance the flow stress and desirable microstructure.