Research On Microstructure And Mechanical Properties Of High Stength And High Platicity TWIP Steel For Automobile

In the 21st century, the lightweight of automobile has become an irreversible trend. TWIP steel attracted much attention by good tensile strength (600?1000 MPa), high elongation (60?90%) and high rate of strain hardening, which can meet the requirements of automotive lightweight. Influence of the content of manganese, annealing and rolling process on microstructural and mechanical properties of Fe-X Mn-3Si-3Al TWIP steel (X=18?26%) was investigated by metallographic observation, microhardness measurement, tensile test and EBSD analysis.The content and results of this paper mainly include:1. Through metallographic observation and microhardness measurement, the paper analyzes the influence of manganese content to the microstructure and recrystallization temperature of TWIP steel.The results show that with the increase of manganese content, the grain size and the annealing twins size of Fe-XMn-3Si-3Al TWIP steel increases,; recrystallization temperature and recrystallization grain size increase; the hardness decrease.2. Through metallographic observation, EBSD analysis and tensile experiments, the paper analyzes the relationship between the grain size and the mechanical properties of Fe-18Mn-3Si-3Al TWIP steel. The results show that the grain size and its uniformity have significant effects on the mechanical properties of TWIP steel:with the increase of annealing temperature, the grain size increases;when the size of the grain is uniformity, the tensile strength decreased, elongation increased;continue to raise the temperature, the grain size of the TWIP steel appears obvious difference, then tensile strength and elongation decreases.3. Rolling the annealed TWIP steel again, then anneal and stretch; study the change of the mechanical properties of TWIP steel before and after the second cold roll. Results show that after the second cold-rolling, strength TWIP steel improving, the plasticity slightly decreasing.The experiment analyzes the TWIP steel from two aspects of microstructure and mechanical properties. It can provide a theoretical basis for the actual production of TWIP steel.