Microstructure and mechanical performances of the coarse grain heat-affected-zone （CGHAZ） for oil tank steel with different Ti content were investigated through Gleeble-3500, scanning electron microscopy, transmissi...Microstructure and mechanical performances of the coarse grain heat-affected-zone （CGHAZ） for oil tank steel with different Ti content were investigated through Gleeble-3500, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometer. The results show that the strength and low- temperature toughness of base material are significantly improved for the high titanium content steel, but the impact toughness of CGHAZ is seriously deteriorated after the high heat input welding and declined sharply with the heat input increasing, while the effects of heat input on impact toughness are very weak for the low titanium content steel, impact toughness of which is gradually larger than that of high titanium content steel with the welding heat input increasing because of the granular bainite increasing, TiN particle coarsening, and （Ti, Nb） N composition evolution during the high input welding for high titanium content steel.展开更多
Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The maj...Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The major reason of boron improving toughness of Bg was to reduce the.quantity of M-A constituents.The reasons of martensitic brittleness in microstructure were discussed in detail.The experimental results proved that the order state of dislocations was an important factor of martensitic brittleness caused by boron, and the higher the order degree of dislocations was, the more brittle the martensite was.展开更多
In this study, the microstructure evolution and corrosion resistance in O. 5 M Na2CO3 - 1 M NaHCO3 solution of X80 high-deformability （ X8OHD ） pipeline steel coarse-grained heat-affected zone （CGHAZ） with several...In this study, the microstructure evolution and corrosion resistance in O. 5 M Na2CO3 - 1 M NaHCO3 solution of X80 high-deformability （ X8OHD ） pipeline steel coarse-grained heat-affected zone （CGHAZ） with several heat input levels were investigated. It is shown that the microstructure of CGHAZ changes from bainite ferrite to granular bainite as the heat input increasing. In addition, the corrosion resistance and the stability of passive film of base material are better than those of CGHAZ with several heat input levels. Too small or too big heat input is inadvisable and better corrosion resistance of CGHAZ is attained when heat input is 30 kJ/cm.展开更多
基金supported by the Fundamental Research Funds for the National Science and Technology Support Program(No.2011BAE25B01)
文摘Microstructure and mechanical performances of the coarse grain heat-affected-zone （CGHAZ） for oil tank steel with different Ti content were investigated through Gleeble-3500, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometer. The results show that the strength and low- temperature toughness of base material are significantly improved for the high titanium content steel, but the impact toughness of CGHAZ is seriously deteriorated after the high heat input welding and declined sharply with the heat input increasing, while the effects of heat input on impact toughness are very weak for the low titanium content steel, impact toughness of which is gradually larger than that of high titanium content steel with the welding heat input increasing because of the granular bainite increasing, TiN particle coarsening, and （Ti, Nb） N composition evolution during the high input welding for high titanium content steel.
文摘Effect of boron on microstructure and toughness of simulated CGHAZ of 790 MPa grade HSLA steel was studied.In the CGHAZ,boron improved the toughness of granular bainite(Bg),but deteriorated that of martensite.The major reason of boron improving toughness of Bg was to reduce the.quantity of M-A constituents.The reasons of martensitic brittleness in microstructure were discussed in detail.The experimental results proved that the order state of dislocations was an important factor of martensitic brittleness caused by boron, and the higher the order degree of dislocations was, the more brittle the martensite was.
基金This work was supported by The National Natural Science Foundation of China （No. 51271099）.
文摘In this study, the microstructure evolution and corrosion resistance in O. 5 M Na2CO3 - 1 M NaHCO3 solution of X80 high-deformability （ X8OHD ） pipeline steel coarse-grained heat-affected zone （CGHAZ） with several heat input levels were investigated. It is shown that the microstructure of CGHAZ changes from bainite ferrite to granular bainite as the heat input increasing. In addition, the corrosion resistance and the stability of passive film of base material are better than those of CGHAZ with several heat input levels. Too small or too big heat input is inadvisable and better corrosion resistance of CGHAZ is attained when heat input is 30 kJ/cm.
