Effects Of Asymmetric Rolling And Annealing Processing On Microstructure And Properties Of Low Carbon Steel

To meet the requirements of market on the properties of metal materials and the shortage of resources. How to effectively produce high performance metal materials has become the focus of scientific research personnel. The properties of metal materials depend on the internal microstructure. Refine grain can improve the properties of metal materials. Therefore, the microstructure and mechanical properties of metal material should be studied.The strip steel was cold rolled by asymmetric rolling technology. The sample with original thickness of 2.0mm was cold rolled to 0.3mm with reduction of 85%. Then the effect of annealing time and temperature on the microstructure and mechanical properties were investigated after the specimens were annealed at different temperature for various annealing time.The mechanical properties and microstructure of the cold rolled samples after annealing related to cold rolling and annealing process.The grains were elongated significantly and high density dislocation(ρ≈1.25×1015m-2) was observed in the strip steel after cold rolling. With increasing of the annealing temperature, high density dislocation and smaller subgrains were observed in the strip steel. It was indicated that the average grain size decreased to 1.24μm from 11.38μm, dislocation density decreased to1.34×1014m-2, hardness of samples increased to 1265.26 Mpa from 1265.26 Mpa, tensile strength is575 Mpa, elongation is improved. And the activation energy for grain growth of278 k J/mol was determined.The microstructure of 45 steel is refined, and the average grain size is 1.8μm, but the microhardness increases after asymmetric rolling and annealing. The microhardness is1900 MPa. Dislocation density drop to 3.63×1012m-2from 1.15×1015m-2. The properties is improved.