Pj. Jacques et al., The developments of cold-rolled TRIP-assisted multiphase steels. Al-alloyed TRIP-assisted multiphase steels, ISIJ INT, 41(9), 2001, pp. 1068-1074
The influence of heat-treating conditions on the retention of carbon-enrich
ed austenite of TRIP-assisted multiphase steel grades containing different
amounts of silicon and/or aluminium is investigated. The ensuing mechanical
properties resulting from the TRIP effect are also scrutinised. The bainit
e transformation kinetics was followed by dilatometry whereas a detailed ch
aracterisation of the microstructures led to the construction of transforma
tion maps giving the volume fractions of the different phases and the carbo
n content of austenite. The role of silicon and aluminium additions (i) on
the retention of austenite by partial bainite transformation and (ii) on th
e mechanical properties is enlightened. A strong influence of the solid-sol
ution strengthening effect of silicon is highlighted. Aluminium seems to be
an effective alloying element for the retention of austenite in TRIP-aided
steels even if lower strength levels can be attained. A mixed Al-Si TRIP-a
ided steel seems to be a very good compromise between the processing needs,
the required mechanical properties and the industrial constraints.