변태유기소성강의 소성변형에 미치는 2차상의 형상과 고용탄소의 영향

Effects of the Morphology of Secondary Phases and Carbon Content on the Plastic Deformation of TRIP steel

The effects of secondary phase morphology and carbon content on the plastic deformation of 0.2C-1.5Si-1.5mn TRIP(TRansformed Induced Plasticity) steel have been investigated at various annealing and bainitic transformation temperatures. The morphology of ferrite and secondary phases was controlled by the annealing temperature and the distribution of secondary phase was controlled by the bainitic transformation temperature. The secondary phase contributed to elongation and/or UTS depending on the ferrite morphology which determined deformation mode simple elongation or rotation of secondary phase along the tensile direction In case of the sample containing the granular type retained austenite the elongation was improved as carbon stabilized the austenite phase. If the film-shape retained austenite in acicular ferrite was dominant however UTS was enhanced as the transformed martensite was hardened by carbon.