A Study On Thermo Hydrogen Processing And Hot Deformation Behavior Of BT20 Alloy

The thermo-compressive behavior and deformation mechanism of BT20 alloy with hydrogen at high temperature were studied in this paper. Relation of hydrided time and hydrogen content was mensurated. Ture stress-ture strain curve of thermo-compressive deformation of BT20 alloy with hydrogen was obstained by Gleeble-1500D and different process parameter effect on it was discussed. Metallomicroscope (MS), transmission electron microscope (TEM) and high resolution electron microscope (HREM) were used to observe microstructure before and after thermo-compressive deformation. Activation energy of deformation was calculated.Deformation behavior and mechanism was discussed by activation energy of deformation and microstructure.Dehydrided process in vacuum was investigated.The hydrided results show relation of hydrided time and hydrogen content meets CH(t)=1.2-1.2exp(-t/120), diffusion flux of solid and gas interface J= 3ρ[exp(-t/120)]/200 with hydrogen partial pressure 0.1MPa and hydrogen flux 990ml?min-1. TEM shows only hydrides were generated until hydrogen content up to 0.76% and hydrides have features as follows: needle convex, habit plane, median ridge, bit vector.Ture stress-ture strain curve of thermo-compressive deformation of BT20 alloy with hydrogen first descends and then rises integrally as hydrogen content increases and peak of flow stress occur in it. Appropriate hydrogen content can reduce peak of flow stress up to minimal value. Strain rate effect on hydrogen content corresponding to minimal value of peak of flow stress.Activation energy of deformation of BT20 alloy with 0.47% hydrogen content and strain rate 8.3×10-4s-1 is 90KJ·mol-1. Hydrogen reduces Activation energy of deformation in 600℃by 50 KJ·mol-1. Activation energy of deformation of BT20 alloy in 800℃is 390KJ·mol-1, Activation energy of deformation of BT20 alloy with 0.47% hydrogen content in 800℃and strain rate 8.3×10-4s-1 is 140KJ·mol-1. MS, TEM and HREM show fault ribbon and twin after deformation.recrystallization occurs in high strain rate in 800℃.Dehydrided result of before and after deformation of BT20 alloy with 0.47%...