| Popis: |
TRIP steels are under development for automotive applications that require high strength and simultaneous high formability. This study was undertaken to examine the phase transformations occurring during the processing of a cold-rolled TRIP steel. The TRIP microstructure is comprised of ferrite, bainite and retained austenite. This microstructure is obtained by controlled cooling from the intercritical annealing temperature to the isothermal bainitic holding temperature. The effects of cooling rate from intercritical annealing temperature to isothermal transformation temperature, as well as isothermal transformation time, were studied via optical microscopy, SEM, TEM, XRD, magnetometry, dilatometry and mechanical testing. A CCT curve for one intercritically annealed TRIP steel was produced. Conclusions are drawn regarding the effects of processing parameters on phase balance (ferrite, bainite, austenite, martensite and pearlite) and mechanical properties. Suggestions for future work are also made. |
