Microstructure And Properties Of Nuclear Power Duplex Stainless Steel2205

The topic was first studied the solution temperature （ST） on nuclear power duplexstainless steel（DSS）2205alloying elements between phases and its corrosion resistance.Then on this basis it were system researched the precipitation behavior of σ phasebetween600℃-1000℃and which effect on microstructure and properties of alloy. Thepaper aims to reveal the precipitation, growing up of the σ phase and effecting on itsproperty, which was designed for this alloy processing technologies laid the foundationand service areas.The effect of ST and high temperature aging process on the microstructure andproperty of nuclear power2205DSS and the effect of aging on the microstructure andproperty were investigated by OM, X-ray diffraction, SEM, TEM, Mechanics Tests andCorrosion tests etc. The results show that:（1） The microstructure were only two phase of ferrite （α）and austenite（γ） after STrange from1050℃to1250℃. The phase proportions of two groups were attained to1:1at1150℃. The EDS shows that the distribution coefficient of Mo element increaseswith increasing ST, Ni and Cr elements in the opposite. The corrosion tests show thatthe alloy surface electric potential is smaller, pitting break potential is maximum after1150℃ST, which have the best corrosion resistance.（2） The research of aging temperature on precipitation behavior of2205DSSshows that: The black granular M₂₃C₆was precipitated in the α/γ phase boundary and αgrain boundary after aging for240min at650℃, the σ phase and χ phase wereprecipitated at750℃-950℃for240min.The maximum content of the precipitation at850℃.（3） The precipitation behavior of σ phase after thermal insulation different time at850℃of2205DSS were indicated that: The σ phase first precipitate at the α/γ phaseboundary and α grain boundary as long as aging at850℃for10min.Along withincreasing aging time the σ phase was grown up into α phase, which is mainly due to the eutectoid reaction αâ†'γ2+σ in the ferrite so that the σ phase content increasescontinuously. The corrosion tests shows that the σ phase can obvious reduce thecorrosion resistance. The formation of σ phase resulted in Cr, Mo depletion in ambientregions, so the pitting corrosion were emerged in this location. the pitting breakpotential reduced with increasing content of σ phase.