Study On The Precipitation Mechanism And Strengthening Mechanism Of Vanadium Carbide In High Manganese Austenitic Steel

High manganese austenitic steel which is an automotive steel have a great advantage either in strength or ductility, and become a development direction of the new generation of high strength and plasticity steel. However, high-manganese austenitic steel is still faced with the problem of strengthening the austenite region. The Ⅴ element is added to improve the strength of steel by precipitation strengthening of the way, while maintaining high ductility, to obtain the TWIP steel which have high strength and high plasticity.There are many ways of carbide precipitation in Fe-Mn alloys with low stacking fault energy. Alloy was cold-rolled with different deformations in order to study the law of precipitation by the microstructure observation, scanning electron microscopy, transmission electron microscopy and other characterization techniques, Through hardness test of The mechanical properties was analysised through hardness test, tensile test. Aging precipitation of solid alloy and the recrystallization of grain with the second phase precipitation of high manganese austenitic steel after adding V was studied.Solid solution alloy of Fe-32Mn-3Al-0.49V-0.36C aged at different temperatures, the increase of the hardness and the strength is not great. It can be determined that V4C3failed to enhance significantly.Fe-32Mn-3Al-0.49V-0.36C alloy was cold-rolled with different deformations in order to promote the precipitation of V4C3, The V4C3precipitation has a significant strengthening effect. The strengthening effect increases with the increase in the amount of cold deformation.V4C3precipited at the dislocations after aging at a lower temperature, which joint action with the recovery of crystal lead the strength of the alloy reduced smaller while the plasticity has greatly improved. The density of dislocation reduced after aging at a high temperature, most V4C3precipited punctate and a few at the dislocation evolution, The size of particle increases which caused over-aging. At the same time, the recrystallization process of grains started. Two effects combined lead to the strength of the alloy is drastically reduced and the plasticity improved significantly. The study showed that the cold-rolled deformation of40%of the Fe-32Mn-3Al-0.49V-0.36C alloy had the best strengthening effect after aging at550℃for5h, the tensile strength increased from1023MPa to1074MPa and the elongation enhanced from7.5%to18.8%.The recrystallization temperature of cold-rolled alloy was determined.The recrystallization temperature of Fe-Mn-Al-C alloy increased after adding Ⅴ,and the recrystallization temperature decreased with the increase in the amount of cold deformation.