Effect of Rolling Temperature on Microstructure and Properties of Fe-18Mn-1.5Al-0.3C High Strength Steel for Automobile

The warm rolling test of hot rolled Fe-18Mn-1.5Al-0.3C high strength and low density steel was carried out at different temperatures from 500℃ to 680℃.The effects of different rolling temperatures on microstructure and mechanical properties of high strength and low density steel were studied by OM, TEM, XRD and tensile tests.The results show that compared with those of the hot rolled test steel, the strength of the 500-680℃ interval rolled test steel is improved and the elongation is decreased.With the increase of rolling temperature, the tensile strength and yield strength of the test steel increase first and then decrease, while the elongation and strength-plastic product decrease first and then increase.The tensile strength and yield strength of the test steel rolled at 560℃ are the highest, which are 1098.2 and 1041.5 MPa, respectively.The elongation and strength-plastic product of the test steel rolled at 680℃ steel are the highest, which are 45.4% and 44.86 GPa·% respectively.With the increase of rolling temperature, the grain boundary of Fe-18Mn-1.5Al-0.3C steel becomes fuzzy, and fine grains appear in the grain boundary of the test steel rolled at 560 ℃.As the rolling temperature continues to rise, the fine grain size gradually increases.