Characteristic Damage of SUS304 Stainless Steel Subjected to Repeated Laser Heating Shocks

Thermal shock tests of SUS304 stainless steel subjected to local, instantaneous and repeated laser heating shocks were carried out to investigate the thermal resistivity and damage of the material. A Nd: YAG pulse laser with the maximum power of 50 J/1 pps was employed as a heating source. The heating damages and microstructures of the heated surface and interior were analyzed with scanning electron micrographs. The experimental results showed the appearance of various damage patterns, depending upon the incident heating energy strength and repeated number. High strength heating shocks induced large-sized internal damages, while low strength and repeated heating shocks induced an interface region between the phase transformation area the base SUS304 stainless steel. This region consists of many microcracks or low strength slender microstructures. These results suggest that the internal damages deserve more attention from the view point of material strength.