This thesis is focused on the study of laser remelting of 17-4PH stainless steel. The 2KW CO_2 laser and 400W pulse YAG laser were used as a pair of a comparative process. The following aspects were investigated: relationship between laser irradiation parameter and laser remelting zone, the effects of aging time and temperature on hardness and microstructure of the remelting zone, and the microstructure changes in aging processes, and so on. The experiment results showed that: After laser remelting and following aging, th hardness of the 17-4PH steel reached HV450, which is more than its conventional age-hardening. Aging dynamic behaviors of laser remelting zone different from its substrate was observed in the study.
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