Investigation Of The Microstructural And Properties Of ODS-HT9 Steel Prepared By Hot-pressing

Travelling-wave reactor(TWR)compared to sodium cooled fast reactor is a new fast reactor.It needs much better comprehensive properties as the fuel cladding.HT9 steel was a candidate materials in TWR.Its properties need improve for meet never replace fuel in all life.Oxide dispersion strengthened(ODS)technology has been usually noticed in advanced anti-radiation properties of HT9 steel.ODS-HT9 steel with the content of HT9 power and nonameter Y2O3 powder were prepared by mechanically milling and hot-pressing technology.The power and fracture microscope were observed by scanning electron microscope(SEM).Oxide microscope and dispersion were observed by transmission electron microscope(TEM).The phase of power and samples was analyzed by X-Ray diffraction(XRD).The influence and mechansim of the ball milling technology,the sintered technology,the content of Y2O3 powder were investigated.The optimal milling paremeters were determined as millng time 30 h,rotational speed at 200 rpm,rational of ball and power at 10:1.Mixed powde morphology was flat.Mixed power particle size was uniform.ODS-HT9 steel samples were obtained by the vacuum hot-pressed sintered technology.The samples properties are obvious influenced by the sintered temperature and sintered press.With the sintering temperature increased,the reative density,the vickers hardness,the tensile strength and elongation of the samples are increased.Because the gap and hole of samples were declined so that microstructure density in the high sintered temperature.But the samples properties are inclined above the sintered temperature 1000℃.Beause the grains are grown up.With the sintering press increased.The reative density,the vickers hardness,the tensile strength and elongation of the samples are increased.Because the powder particle are sintered together and the grain gap and hole of samples are inclined.The relative density has a significant increased.With sintering press increased,the samples relative density and properties have only a few changes when the sintered press is reached worth.The content of Y2O3 has a significant effect on properties of samples.With the increase of the Y2O3 content,The vickers hardness and the tensile strength of the samples are increased,but the elongation reduces.With the Y2O3 content increased,the oxide dispersion particles are increased in HT9 steel.The dislotion lines meet oxide dispersion particle in much more chance.The dislotion lines are more likely to obstacled by the oxide dispersion particles.The materials are difficultly out of shape.So the vickers hardness and the tensile strength of the samples are increased,but the elongation reduces.The samples were obtained by mechanically milling and hot-pressing technology.With the sintering temperature 1050℃,the sintering press 30 MPa and 0.3%(mass fraction)content of Y2O3,the samples got well combined properties.The grain size is small and dispersion in the samples.The oxide dispersion particles of the diameter 40nm are about sphere and uniform distribution in the HT9 steel.The relative density of samples is reached to 97.5%.The vickers hardness,the tensile strength and elongation are also reached to 620,912.2 MPa and 11.2%,respectively.