Two-Sublattice Thermodynamic Model on Carbonitride Precipitation in Microalloyed Steels Bearing Nb-V

• 出 处: Journal of Iron and Steel Research(International)
• 发表日期: 2011年S1期
• 关键词: titanium vanadium Precipitation starting austenite steels nitride interstitial h

Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon steel.The calculation results show that starting-temperature of the precipitation of niobium carbonitride,vanadium carbonitride and titanium carbonitride are 1100℃,920℃ and 1340℃,respectively,the mole fraction of carbonitride precipitates is 8.65×10-4 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti0.029V-Fe steel.When the N content is from 0.0028% to 0.0056%,the starting-temperature of the precipitation of the titanium carbonitride changes from 1340℃ to 1430℃.And the C content is from 0.053% to 0.07%,the startingtemperature of the precipitation of the titanium carbonitride hardly changes,but the atomic fraction of niobium in the carbonitride obviously increases.

Based on the two sublattice model of the regular solution, one being metal atom sublattice and another being interstitial atom sublattice, a thermodynamic model for the precipitates of niobium carbonitride, vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon steel. Calculation results show that starting-temperature of the precipitation of niobium carbonitride, vanadium carbonitride and titanium carbonitride are 1100 ° C, 920 ° C and 1340 ° C, respectively, the mole fraction of carbonitride precipitates is 8.65 × 10-4 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti0.029V-Fe steel. The content of the N content is from 0.0028% to 0.0056%, the starting-temperature of the precipitation of the titanium carbonitride changes from 1340 ° C to 1430 ° C. And the C content is from 0.053% to 0.07%, the starting temperature of the precipitation of the titanium carbonitride hardly chan ges, but the atomic fraction of niobium in the carbonitride obviously increases.