In order to study the structural performance of TP304H austenite heat-resisting steel used in long-term high-temperature and high-pressure

and having occurred overheat tube-burst

the metallugical structural analysis

electronic probe test

scanning electronic microscopic spectrum analysis

and mechanic property test under normal atmospheric temperature etc.have been carried out onto the specimens.Results of study show that the carbide Cr23C6 may separate out in the structure of TP304H austenite heat-resisting steel

and σ phase being separated out along grain boundaries

under high-temperature and high-pressure

thereby

resulting in decrease of impact toughness

plasticity

and anti-oxidation property of said steel

making poor chronium being produced along grain boundories in the solid solution

increasing the sensitivity of grain boundary corrosion.The more σ phase separated out

the lower strength of TP304H steel becomes.