不同碳含量碳钢淬火态马氏体精细结构

Martensitic substructure in quenched Fe-C binary alloys with different carbon contents was investigated by transmission electron microscopy (TEM). The results show that the initial or first-formed martensite of the steel with different carbon contents is composed of body-centered cubic (bcc) {112}<111>-type twinning structure with ultra-fine ω-phase particles (1-2 nm) at the twinning boundary region. Due to the high starting temperature of martensite transformation in low-carbon steel, the microstructure of martensite observed at room temperature is the product of twin and ω phase by self-tempering. Medium carbon and high carbon steels have lower martensite transformation starting temperature, and their self-tempering effect is weak, which makes phase transformation twins and ω phases relatively intact at room temperature.