Abstract: Effect of solution temperature on microstructure and mechanical properties of hot-rolled Fe-30Mn-10Al-1C low density steel was studied by means of OM, SEM, TEM and tensile test. The reasons for microstructure evolution and mechanical properties change were clarified. The results show that the Fe-30Mn-10Al-1C low-density steel is austenitic single-phase structure after hot rolling and solution treatment. A large number of annealing twins appear after solution treatment. The average grain size increases from 34 μm to 138 μm when the temperature is increased between 950-1050 ℃. With the increase of solution temperature, micron κ carbide disappears gradually. However, due to the extremely low nucleation barrier and high degree of subcooling, a large amount of nano-κ carbides are still formed after solution treatment. The tensile strength and yield strength of the as-rolled tested steel are the highest, reaching 1188 MPa and 1123 MPa, respectively, but the elongation is the lowest (33%). With the increase of solution temperature, the tensile strength and yield strength of the tested steel gradually decrease, and the elongation continuously increases. At 1050 ℃, the tensile strength and yield strength are 853 MPa and 726 MPa, respectively, and the elongation reaches 61%.

Key words: low density steel, solution temperature, austenite, microstructure, mechanical properties