3. The poor corrosion resistance property of original substrate was mainly caused by the existence of rich and poor Cr regions, and the large potential difference between ferrite and pearlite (easy to formcorroding microcells), so a large of corrosion pits had been generatedon the surface of the corroded original substrate, which even accumulatedtogether to form lager corrosion holes. However, the degree ofcorrosion of laser transformation hardened samples were improvedobviously because of the formation of martensite and the precipitationof Cr atoms.