Effect of cold rolling reduction on microstructure and mechanical properties of Fe-10Mn-6Al-0.4C steel
Fe-Mn-Al-C medium manganese steel has broad application prospects due to its low density,high strength and high plasticity.In the experiment,Fe-10Mn-6Al-0.4C was used as the research object.After hot roll-ing,it was annealed at 700 °C for 60 min and air-cooled to room temperature.Subsequently,they were cold rolled at 40%,60%and 70%reduction ratio,respectively.After cold rolling,they were annealed at 750 °C for 30 min and air-cooled to room temperature.The microstructure evolution after cold rolling and annealing was detected by SEM and EBSD,and the mechanical properties were measured by universal tensile testing machine.The results show that the microstructure of cold rolled plate is composed of banded δ ferrite,martensite(M),austenite(A)and α ferrite.The microstructure of the annealed plate is composed of α ferrite,austenite and banded δ ferrite.With the increase of cold rolling reduction rate,the microstructure of the annealed sheet is layered structure,and the average grain size,the pro-portion of fine grain and the proportion of austenite phase composition decrease first and then increase,while the degree of recrystallization increases from 69%to 83.5%,and the GND density of the annealed sheet decreases.When the reduction rate is 60%,the GND density in austenite decreases sharply.The annealed plate is composed of fine equiaxed austenite,α ferrite and banded δ ferrite.The ferrite grain size is bimodal distribution.The yield strength is 818.7 MPa,the tensile strength is 962.3 MPa,the elongation is 34.3%,and the product of strength and plasticity is 33.01 GPa·%.The combination of strength and plasticity is excellent.The tensile fracture shows that the tensile fracture with a reduction rate of 60%has dense and fine dimples,which promotes the elongation of the annealed plate,while the reduction ratio of 40%and 70%have different degrees of cleavage steps,which deteriorates the elongation.Controlling the reduction rate combined with short-time annealing can form a layered structure under the premise of reducing the process cost,thereby improving the mechanical properties of the material.
medium manganese steelrolling reduction ratiomicrostructuremechanical propertylightweight
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