Effect of Deformation Parameters on Microstructure of Ultra-high Nitrogen Austenitic Steel Used for Retaining Ring
Gleeble 3500 high temperature thermal simulation test machine was used to conduct high temperature compression deformation of ultra-high nitrogen austenitic steel for retaining ring.By metallographic microscope,scanning electron microscope and energy spectrum analysis methods,the microstructure and morphology of the steel after thermal deformation was analyzed.Using transversal method and quantitative metallography,the quantitative relationship between the critical stress and peak stress of dynamic recrystallization and Z parameter was determined.The results show that during the hot deformation of the test steel,when the degree of deformation and the deformation temperature are fixed,the lower the strain rate,the easier dynamic recrystallization occurs and the greater the degree of dynamic recrystallization.When the deformation degree and strain rate are fixed,the higher the deformation temperature,the larger the recrystallized grain size,the larger the volume fraction of recrystallized grains,the greater the dynamic recrystallization degree.During the hot deformation,the second phase precipitates appear in the crystal grains and grain boundaries of the test steel.These precipitates are MX-type composite precipitates(Nb,V)N.
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