The Research On Mechanism Of GH4133B Superalloy After Fatigue At Elevated Temperature

The nickel-base superalloy GH4133B is widely used as main turbine disk and other machines used at elevated temperature.Under 700℃of temperature GH4133B has stable microstructure,and withstand a large force of dynamic in a elevated temperature.So there was some huge signficance to research the properties of fatigue, and S-N curves of GH4133B is the critical ability among mechanical properties.This paper studied variation of microstructure and mechanical property of nickel-base GH4133B superalloy after fatigue testing ranging between 500℃and 800℃by means of optical microscope,grain size analysis,scanning electron microscope,EDS analysis and transmission electron microscope etc.The results of these studies indicates fatigue values vary as elevated temperature vary.As the elevated tempter increased from 500℃to 700℃,the fatigue strengths(the strengths of fatigue limit about S-N curves)are stronger.But the temperatureof 800℃,the fatigue's properties of GH4133B fatigue deterioration rapidly.GH4133B superalloy is a nickel-base and solid solution superalloy,in whichγ' phase dispersed is the primary strengthening phase.When temperature be raised to 700℃,the amount ofγ' phase precipitated is the most,and the distribution ofγ' phase is regular,and then the strengthening attain the most value.But around the 800℃the fatigue values fall rapidly because distribution ofγ' phase is bad througth gathering and growing.The carbide in grain boundaries prevent from shifting,and the massive carbide inside of grain reinforce the strengths somewhat.The carbide changes from brittleness to plasticity as the temperature is elevated,then carbide stronger strengths of boundary at elevated temperature.As well as the primary phase—γ' phases gather and grow,but the variation of fatigue at elevated temperature are decided on the variation of both the carbide andγ' phase at range between 500℃and 800℃.The amount,shape and distribution ofγ' phase influence the strength of elevated fatigue of GH4133B superalloy,and carbide limited the rising of strength of elevated fatigue.