0.15C-1.5Si-1.5Mn TRIP 냉연강판의 미세조직과 기계적 성질에 미치는 열처리의 영향 = Mechanical Behavior;Effects of Heat-Treatment on Microstructures and Mechanical Properties of a 0.15C-1.5Si-1.5Mn TRIP Cold-Rolled Steel Sheet

다국어 초록 (Multilingual Abstract)

The main emphasis of the present study has been placed on understanding the effects of heat-treatment (intercritical annealing and isothermal treatment) on the microstructures and mechanical properties of a cold-rolled 0.15C-1.5Si-1.5Mn steel sheet. The steel sheet was intercritically annealed, and isothermally treated at bainitic region following air cooling. Microstructural observation and tensile tests were conducted, and also the volume fractions of retained austenite were measured. The volume fractions of retained austenite and the mechanical properties of the steel sheet was changed dramatically by heat-treatment conditions, and the volume fractions of retained austenite increased with decreasing intercritical annealing temperature and isothermal treatment temperature, resulting in the improvement of tensile elongation and strength-ductility balance (TS×Elong.) without huge decrease of the yield or tensile strength. From the results of the present study, it is reached a conclusion that the conditions (temperature and time) of intercritical annealing and isothermal treatment should be established in consideration of the stability of austenite with the solubility of alloying elements in the austenite formed during the intercritical annealing.