Hot Deformation Behavior And Properties Of Nb-V Ultra-high Nitrogen Austenitic Steel

The high nitrogen steel prepared by adding a certain amount of nitrogen to the steel material has excellent mechanical and chemical properties.Nickel-free high nitrogen austenitic stainless steel has a low cost,which avoids the biological allergy caused by nickel element and broadens the application field of austenitic stainless steel.At present,Mn18Cr18N and 16Cr13Mn3Mo0.9N steel used in the manufacture of high-power generator retaining rings are common types of high-nitrogen steel.The effect of the addition of microalloying elements Nb and V on the performance of traditional steels has been confirmed,but there are few reports on the impact of microalloying elements on the properties of ultra-high nitrogen austenitic steels,especially the effect on hot workability needs in-depth study.The deformation behavior was studied.1000?1150?and 0.01?10 s^-1,the flow stress increases with the increase of strain rate and the decrease of temperature.After calculation,the activation energy is:714 k J/mol;the thermal deformation equation is:?(5)=2.362×10²⁵[sinh(0.00572?)]^5.69exp(-714256/RT);relationship between peak stress and Z parameter:?_p=26.725ln Z-1407.76(MPa).The thermal processing diagram of the test steel was drawn,processing window:1040?1100?,0.25?4 s^-1.The necklace dynamic recrystallization was observed at 1000?1050?,and the classical dynamic recrystallization at 1100?1150?.At 0.01?1 s^-1,the recrystalli-zation is driven by the storage energy produced by the dislocation density plug;10 s^-1 is driven by twinning.Nb and V lead to MX type nitride precipitation.During the deforma-tion,the precipitates restricted dislocation and grain boundary migration,resulting in increased stress and activation energy.Nb and V content will affect precipitation behavior and further affect recrystallization.The suitable hot rolling process can obtain good mechanical properties.With the increase of the final rolling temperature,the amount of press-down and the cooling rate,the recrystallization rate increased,the grain refined,the precipitate content decreased and the dispersion degree increased,so as to obtain better strength and plasticity.Figure 47;Table 12;Reference 99...