Tensile Properties and Stretch-Flangeability of TRIP Steels Produced by Quenching and Partitioning (Q&P) Process with Different Fractions of Constituent Phases

The influence of microstructure on tensile properties and stretch-flangeability TRIP steels with strengths higher than 1.2 GPa has been investigated under various Quenching Partitioning (Q&P) conditions. As lowering the quenching stop temperature, QT, below Ms temperature in range 340°C to 280°C, volume fractions tempered martensite retained austenite increased bainite fresh decreased final microstructure. QT 280°C 330°C, more relative proportion untransformed at end partitioning step was transformed into martensite. microstructural characteristics different conditions were analyzed by EBSD. phase identified a new method applying threshold values both Image Quality (IQ) Kernel Average Misorientation (KAM). It is suggested that decrease HER (Hole Expansion Ratio) value increasing due increase size fraction particle.