固溶处理对Fe-30Mn-10Al-1C低密度钢组织及力学性能的影响

借助OM、SEM、TEM、拉伸试验等手段研究了固溶温度对热轧Fe-30Mn-10Al-1C低密度钢组织及力学性能的影响,并阐明了其组织演变和力学性能变化的原因。结果表明,试验钢经热轧及固溶处理后组织均为奥氏体单相组织,固溶处理后出现大量退火孪晶;950~1050 ℃固溶时,平均晶粒尺寸随温度的升高由34 μm增长至138 μm;随着固溶温度的升高,微米κ碳化物逐渐固溶消失,但由于较低成核势垒和较大的过冷度,固溶后仍有大量纳米κ碳化物生成;试验钢轧态的抗拉强度和屈服强度最高,分别为1188 MPa和1123 MPa,但伸长率最低为33%;随固溶温度的升高,试验钢抗拉强度和屈服强度逐渐降低,伸长率则不断升高,1050 ℃时抗拉强度和屈服强度分别为853 MPa和726 MPa,伸长率达到61%。

Effect of solution treatment on microstructure and mechanical properties of Fe-30Mn-10Al-1C low density steel

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%.