EBSD Characteristics of HSLA100 Steel Quenched in the 2-Phase Region

Abstract

The grain and grain boundary characteristics of HSLA100 steel quenched in the 2-phase region were investigated by electron backscatter diffraction (EBSD).The results showed that the austenite amount was controlled by the 2-phase region heating temperature and the composition and morphology of transformation products were mostly depended on the carbon content in austenite. With the quenching temperature in 2-phase region increasing, the dislocation density in bainite decrease as a result of the block bainite coarsening and mergering, which makes the subgrains with much more low angle grain boundaries (2°~15°) decreasing and the massive ferrite with more high angle grain boundaries increasing gradually. Furthermore, the lath martensite or bainite with high angle grain boundaries and subgrains with low angle grain boundaries gradually increase owing to new austenite grain increasing and growing up. With the roles of above two interactions, some EBSD characteristics such as the packet size and the number fraction of high angle grain boundaries all have a peak present at 740°C