Influence of Sc content on microstructure and stress corrosion cracking behavior of medium strength AI-Zn-Mg alloy have been investigated by optical microscopy, scanning electron microscopy, electron backscatter diffr...Influence of Sc content on microstructure and stress corrosion cracking behavior of medium strength AI-Zn-Mg alloy have been investigated by optical microscopy, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy and slow strain rate test. The results indicate that the addition of Sc results in the formation of the quaternary coherent AI3（Sc, Zr, Ti） dispersoids during homogenization treatment, which will inhibit the dynamic recrystallization behavior. The number density ofAl3（Sc, Zr, Ti） particles increases with the increase of Sc content, and thus the recrystallization fraction of hot-extruded alloy is reduced and the peak strength in two-stage artificial aging sample is enhanced. At the same time, the wide of precipitation free zone is reduced, and the content of Zn and Mg in grain boundary particles and precipitation free zone is increased with the increase of Sc content. In peak-aged state, the 0.06 wt% Sc added alloy shows the better stress corrosion cracking resistance than the Sc-free alloy because of the reduction of recrystallization fraction and the interrupted distribution of grain boundary precipitates along grain boundary. However, the further addition of Sc to 0.11 wt% will result in the deterioration of stress corrosion cracking resistance due to the increase of electrochemical activity of grain boundary particles and precipitation free zone as well as hydrogen embrittlement.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.展开更多
The 34CrMo4 （AISI 4130） steel is extensively utilized in the compressed natural gas cylinders. Due to the importance of thermomechanical processing in the production of these cylinders, the dynamic reerystallization...The 34CrMo4 （AISI 4130） steel is extensively utilized in the compressed natural gas cylinders. Due to the importance of thermomechanical processing in the production of these cylinders, the dynamic reerystallization （DRX） characteristics of 34CrMo4 steel were investigated. The effect of hot deformation parameters such as temperature and strain rate on the dynamic restoration processes of a 34CrMo4 alloy was studied. Hot compression tests were performed in the temperature range of 900 to 1 100 ℃ and the strain rate range of 0. 001 to 0.1 s-1. Hot workability of this alloy has been analyzed by employing flow localization parameter. The flow curves observed are typical of occurrence of dynamic recrystallization and have exhibited single or multiple peaks in flow stress curve before reaching steady state, depending on the temperature and strain rates. The flow stress decreases with the increase of deformation temperature and the decrease of strain rate. Finally the activation energy obtained in this research is 490. 749 kJ/mol.展开更多
Low carbon steels microalloyed with small amount of carbide and/or nitride forming elements such as Nb,Ti and V with Thermomechanical controlled processing (TMCP) can give fine grained ferrite structure with high stre...Low carbon steels microalloyed with small amount of carbide and/or nitride forming elements such as Nb,Ti and V with Thermomechanical controlled processing (TMCP) can give fine grained ferrite structure with high strength and superior toughness.The present study was aimed at identifying rolling parameters as well as microstructural characterization for accomplishing high yield strength and high charpy impact property at-60℃ by controlling hot rolling parameters and microstructure Grain size distribution was also monitored and related to mechanical properties of steel.展开更多
基金supported by the State’s Key Project of Research and Development (Grant Nos. 2016YFB1200600, and 2016YFB1200504)the Strategic Priority Program of the Chinese Academy of Sciences (Grant No. XDB22000000)
文摘Influence of Sc content on microstructure and stress corrosion cracking behavior of medium strength AI-Zn-Mg alloy have been investigated by optical microscopy, scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy and slow strain rate test. The results indicate that the addition of Sc results in the formation of the quaternary coherent AI3（Sc, Zr, Ti） dispersoids during homogenization treatment, which will inhibit the dynamic recrystallization behavior. The number density ofAl3（Sc, Zr, Ti） particles increases with the increase of Sc content, and thus the recrystallization fraction of hot-extruded alloy is reduced and the peak strength in two-stage artificial aging sample is enhanced. At the same time, the wide of precipitation free zone is reduced, and the content of Zn and Mg in grain boundary particles and precipitation free zone is increased with the increase of Sc content. In peak-aged state, the 0.06 wt% Sc added alloy shows the better stress corrosion cracking resistance than the Sc-free alloy because of the reduction of recrystallization fraction and the interrupted distribution of grain boundary precipitates along grain boundary. However, the further addition of Sc to 0.11 wt% will result in the deterioration of stress corrosion cracking resistance due to the increase of electrochemical activity of grain boundary particles and precipitation free zone as well as hydrogen embrittlement.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.
文摘The 34CrMo4 （AISI 4130） steel is extensively utilized in the compressed natural gas cylinders. Due to the importance of thermomechanical processing in the production of these cylinders, the dynamic reerystallization （DRX） characteristics of 34CrMo4 steel were investigated. The effect of hot deformation parameters such as temperature and strain rate on the dynamic restoration processes of a 34CrMo4 alloy was studied. Hot compression tests were performed in the temperature range of 900 to 1 100 ℃ and the strain rate range of 0. 001 to 0.1 s-1. Hot workability of this alloy has been analyzed by employing flow localization parameter. The flow curves observed are typical of occurrence of dynamic recrystallization and have exhibited single or multiple peaks in flow stress curve before reaching steady state, depending on the temperature and strain rates. The flow stress decreases with the increase of deformation temperature and the decrease of strain rate. Finally the activation energy obtained in this research is 490. 749 kJ/mol.
文摘Low carbon steels microalloyed with small amount of carbide and/or nitride forming elements such as Nb,Ti and V with Thermomechanical controlled processing (TMCP) can give fine grained ferrite structure with high strength and superior toughness.The present study was aimed at identifying rolling parameters as well as microstructural characterization for accomplishing high yield strength and high charpy impact property at-60℃ by controlling hot rolling parameters and microstructure Grain size distribution was also monitored and related to mechanical properties of steel.
