Abstract: Microstructure and mechanical properties of a high aluminum low-density steel after solution treatment and continuous annealing treatment in simulated production line were analyzed by OM, SEM, tensile test and hardness test. The effects of solution treatment and aging temperatures on the microstructure and properties of the tested steel were studied. The results show that as the solution treatment temperature increases, the number of carbides in the tested steel structure decreases. When the solution treatment temperature reaches 1050 ℃, all the carbides dissolve into the matrix and the grain size significantly increases, resulting in a significant decrease in the strength of the tested steel. When solution treatment temperature is 950 ℃, most of the carbides have dissolved into the matrix, and the grain size is not significantly increased, exhibiting excellent comprehensive properties. After continuous annealing treatment in simulated production line, the microstructure is composed of ferrite matrix and precipitated carbides. As the aging temperature increases, the number of carbides gradually increases. There is not much difference in the strength at different aging temperatures, but after the aging temperature reaches 350 ℃, the grain size grows and the elongation after fracture significantly increases.

Key words: low-density steel, solution treatment temperature, aging temperature, simulated continuous annealing in production line, microstructure, mechanical properties