Surface mechanical attrition treatment (SMAT) was applied to the samples of a type AISI 304 stainless steel in order\r\nto induce grain refinement as well as formation of twins. Transmission electron microscopy and X-ray diffraction\r\nanalysis results showed that the average grain size at the surface of the SMATed sample was about 10 nm. The\r\nuntreated and SMATed samples were then welded using a one-pass gas tungsten arc procedure. The heat-affected\r\nzone (HAZ) of the samples was examined by optical microscopy and corrosion tests. Results of the double loop\r\nelectrochemical potentiokinetic reactivation tests showed that the degree of sensitization in the HAZ for the\r\nSMATed sample was very low as compared to that of the untreated one. The pre-SMATed sample was resistant to\r\nintergranular corrosion. This is mainly due to the formation of high density of twins which are not prone to carbide\r\nprecipitation because of their regular and coherent atomic structure and extreme low grain boundary energy as\r\ncompared with those of other grain boundaries.
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