Effect of Deformation Parameters on Microstructure Evolution of FGH4113A Powder Metallurgy Superalloy
Through a series of hot compression tests on a novel powder metallurgy superalloy FGH4113A(WZ-A3),the effects of deformation temperature,strain rate and strain on the microstructure evolution were investigated.The results demonstrate that when the temperature is 1100 ℃,the strain rate is 0.1 s-1 and the true strain is between 0.1 and 0.7,the increase in strain is beneficial to promoting dynamic recrystallization and grain refinement.With the increase in strain,the volume fraction of γ'phase first decreases,then increases,and eventually remains stable.The morphology of γ'phase gradually becomes spherical during the thermal deformation process.Under the conditions of temperature 1100 ℃,deformation 50％and strain rate of 0.01-1 s-1,the increase in strain rate can improve the degree of dynamic recrystallization and refine the grains.With the increase in strain rate from 0.01-0.1 s-1 to 1 s-1,the adiabatic temperature rises and dislocation slip intensifies,reducing the volume fraction of γ'phase by about 2％.When the strain rate is 0.1 s-1 and the deformation is 50％,the increase in deformation temperature can promote dynamic recrystallization and grain growth in the temperature range of 1070-1160 ℃.With the deformation temperature rising to 1130 ℃,a large quantity of γ'phase has dissolved,the ability to pin the grain boundary has been significantly weakened,and the average grain size has increased to 12.1 μm.At the deformation temperature of 1100 ℃,strain rate of 1 s-1 and deformation of 50％,fine and uniform γ+γ'dual-phase structure with the grain size above ASTM 12 can be obtained.
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