Effect of Al on the Microstructure and Mechanical Properties of Hot-Rolled Medium-Mn Steel

Abstract:

The present investigation was made to study the effect of Al on the microstructure and mechanical properties of hot-rolled medium-Mn TRIP steel (abbreviated as Al-TRIP). As a contrast, a Si-added medium-Mn TRIP steel (abbreviated as Si-TRIP) was also studied. Addition Al in medium-Mn steel can raise Ac3 temperature, which will restrain austenite transformation and expand the two-phase region, promoting Mn and C elements enriched in austenite. In-depth microstructure and mechanical properties analysis were carried out for the hot-rolled Al-TRIP and Si-TRIP steels in this study. The microstructure was characterized by scanning electron microscope (SEM) and electron probe microanalyzer (EPMA). Volume fraction of retained austenite was measured by D/max2400 X-ray diffractometer (XRD). A dual-phase microstructure consisting of ultra-fine grained intercritical ferrite (IF) and lath-like retained austenite (RA) with high mechanical stability was obtained after annealing at 630°C for 2h for Al-TRIP steel. As prolonging the intercritical annealing time, the stability of RA decreased primarily due to the increase of grain size. The tensile test results indicated that the Al-TRIP steel possessed a better combination of tensile strength and elongation compared to Si-TRIP steel. Excellent mechanical properties with yield strength of 790MPa, tensile strength of 1050MPa, total elongation of 35% and UTS×TEL of 39GPa·% was obtained for the Al-TRIP steel.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 292-298
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.292
• Online since: December 2018
• Authors: Ding Ting Han, Yun Bo Xu*, Ying Zou, Zhi Ping Hu, Shu Qing Chen, Yong Mei Yu
• Keywords: Aluminium, Austenite Stability, Intercritical Annealing, Medium-Mn Steel, TRIP Effect

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