Annealing temperature of Fe-2.0Mn-4.7Al-0.4C steel was determined to be 860 ℃ by using JMatPro simulation software.The effect of annealing time on the microstructure and mechanical properties of the hot-rolled Fe-2.0Mn-4.7Al-0.4C steel was studied by means of optical microscope,scanning electron microscope,and electronic universal material testing machine.The results show that after annealing treatment,the microstructure of the hot-rolled Fe-2.0Mn-4.7Al-0.4C steel transforms from δ ferrite,α ferrite,martensite,pearlite,and cementite to 8 ferrite,pearlite,and retained austenite.When annealed for 120 min,the tensile fracture morphology of the specimen shows a transition from brittle fracture to ductile fracture.The tested steel has the best comprehensive mechanical properties with tensile strength of 515.6 MPa,yield strength of 361.0 MPa,maximum elongation of 35.4％,and strength-elongation product of 18.3 GPa·％.However,when the annealing time is too long to reach 180 min,the grain grows and aggregates,the dislocation movement disappears,resulting in a decrease in material toughness and an increase in material brittleness.The fracture surface is mainly composed of ductile dimples and relatively smooth cleavage surfaces.
关键词
低密度钢/退火时间/断口形貌/显微组织/力学性能
Key words
low density steel/annealing time/fracture morphology/microstructure/mechanical properties
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