Abstract: The experiments were carried out on laser surface alloying of F. G. cast iron with pure Si Powder. The composition of the solidified structures located in the range of ≤2.0%C and 1.62%～9.21%Si. The processing and mechanism of rapid solidification were discussed. During the quick heating by laser beam and subsequent rapidly self-quenching the solidification rate and temperature gradient were chanted, which determined the morphology and seale of the solidified structure. By means of SEM with EPMA system and TEM, the details of structure and phase were observed. The hardening mechanisms of the alloyed structures were reveled. The structure had not only high hardness value of 830～1120HV, but also high wear resistance which was shown in wear testing.

Key words: F. G. Cast iron, Solidification, Surface alloying, Wearing resistance