The　hot　corrosion　tests　of　the　austenitic　TP347HFG　in　molten　sulfates　with　and　without　external　stresses　were　conducted　at　700　and　750　oC.　The　corroded　specimens　of　different　conditions　were　investigated　through　measurements　of　o　xide　morphology,　corrosion　thickness　and　composition.　Through　the　analysis　to　the　corrosion　specimens,　we　knew　that　the　corrosion　reaction　of　the　alloy　was　strongly　related　to　the　formation　of　an　oxidation　progress　of　metallic　elements.　The　unstressed　specimens　had　more　complex　products　and　thicker　corrosion　layers　than　those　under　20MPa　external　stresses　at　700　and　750　oC,　which　meant　mo　re　fierce　corrosion　behaviors.　It　seemed　that　the　applied　stress　led　to　a　faster　formation　of　a　continuous,　dense　oxides　layer　that　protected　the　inner　specimens　fro　m　further　corrosion　reaction.　Generally,　the　exertion　of　the　stresses　caused　many　micro　cracks　and　defects　in　the　metal.　These　defects　acted　as　faster　and　easier　diffusion　paths　for　the　Cr　atoms　to　diffuse　to　the　surface,　and　thus,　promote　a　faster　formation　of　the　protective　Cr2O3　oxide　layer.　©　2015　The　Japan　Society　of　Mechanical　Engineers.