As-quenched low-carbon martensitic steels (<0.2 wt.% C) contain auto-tempered carbides. Auto-tempering improves the work hardening and upper-shelf impact energy; however, an efficient characterization method to determine the degree of auto-tempering has not been available. This paper demonstrates an efficient image processing tool that calculates the relative auto-tempered carbide fraction by analyzing scanning electron microscope micrographs. By the process of image segmentation, the qualitative volume fraction of auto-tempered carbides can be determined, and an associated color map produced, which distinguished the levels of auto-tempering. This image processing tool could become useful for the optimization of new low-carbon steel’s mechanical properties.
