The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal ...The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal simulator. The results showed that the high-Nb steels have excellent weldability. Ernbrittlement regions appear in coarse grain heat affected zone （CGHAZ） and intercritically heat affected zone （ICHAZ） ~ Softening region appears in fine-grain heat affected zone （FGHAZ）, and the strength here was even lower than 555 MPa as required in the standard. Meanwhile, with the increase of heat input, the strength and the toughness of HAZ of steel with high Nb, C and lower alloy decrease notably. Therefore, take into account the welding procedure during manufacture of weld pipe, suitable amount of alloy elements, such as Cr, Ni, Cu, Mo and so on, is necessary for high Nb X80 heavy- thick steel plate.展开更多
Ultra-high strength pipeline steels were rolled by thermal mechanical controlling process (TMCP),and effects of the volume fraction,the size and microstructure morphologies of three different bainite (AF,GB and LB) on...Ultra-high strength pipeline steels were rolled by thermal mechanical controlling process (TMCP),and effects of the volume fraction,the size and microstructure morphologies of three different bainite (AF,GB and LB) on mechanical properties were investigated by optical microscope.The results showed that,X120 ultra-high strength pipeline steel was rolled through the reasonable thermal mechanical controlling process (TMCP),and the yield strength and the low temperature charpy impact energy (-30℃) were higher than 840MPa and above 230J,respectively,meanwhile,the ratios of tensile strength to yield strength were lower below 0.82.As for X100 pipeline,of which the mechanical property were higher than that by X100 pipeline steel of ISO standard,yield strength of the steel was 715 MPa,ultimate tensile strength 963 MPa,impact energy 282J,and yield ratio 0.74.展开更多
The hydrogen induced cracking （HIC） behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite （F＋B）, ferrite and martensite/austenite is...The hydrogen induced cracking （HIC） behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite （F＋B）, ferrite and martensite/austenite islands （F＋M/A） and ferrite and martensite （F＋M）, respectively. The HIC test was conducted in hydrogen sulfide （H2S）-saturated solution. The results showed that the steels with F＋B and F＋M/A dual-phase microstructures had both higher deformability and better HIC resistance, whereas the harder martensite phase in F＋M microstructure was responsible for the worst HIC resistance. The band-like hard phase in dual-phase mi- crostructure was believed to lead to increasing susceptibility to HIC.展开更多
基金Item Sponsored by National Natural Science Foundation of China(51171162)Natural Science Foundation of Hebei Province of China(E2011203169)The R&D Project of CITIC-CBMM(2011-D056-3)
文摘The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal simulator. The results showed that the high-Nb steels have excellent weldability. Ernbrittlement regions appear in coarse grain heat affected zone （CGHAZ） and intercritically heat affected zone （ICHAZ） ~ Softening region appears in fine-grain heat affected zone （FGHAZ）, and the strength here was even lower than 555 MPa as required in the standard. Meanwhile, with the increase of heat input, the strength and the toughness of HAZ of steel with high Nb, C and lower alloy decrease notably. Therefore, take into account the welding procedure during manufacture of weld pipe, suitable amount of alloy elements, such as Cr, Ni, Cu, Mo and so on, is necessary for high Nb X80 heavy- thick steel plate.
文摘Ultra-high strength pipeline steels were rolled by thermal mechanical controlling process (TMCP),and effects of the volume fraction,the size and microstructure morphologies of three different bainite (AF,GB and LB) on mechanical properties were investigated by optical microscope.The results showed that,X120 ultra-high strength pipeline steel was rolled through the reasonable thermal mechanical controlling process (TMCP),and the yield strength and the low temperature charpy impact energy (-30℃) were higher than 840MPa and above 230J,respectively,meanwhile,the ratios of tensile strength to yield strength were lower below 0.82.As for X100 pipeline,of which the mechanical property were higher than that by X100 pipeline steel of ISO standard,yield strength of the steel was 715 MPa,ultimate tensile strength 963 MPa,impact energy 282J,and yield ratio 0.74.
基金Item Sponsored by National Key Technology Research and Development Program of China(2011BAE25B03)
文摘The hydrogen induced cracking （HIC） behavior of a high deformability pipeline steel was investigated with three different dual-phase microstructures, ferrite and bainite （F＋B）, ferrite and martensite/austenite islands （F＋M/A） and ferrite and martensite （F＋M）, respectively. The HIC test was conducted in hydrogen sulfide （H2S）-saturated solution. The results showed that the steels with F＋B and F＋M/A dual-phase microstructures had both higher deformability and better HIC resistance, whereas the harder martensite phase in F＋M microstructure was responsible for the worst HIC resistance. The band-like hard phase in dual-phase mi- crostructure was believed to lead to increasing susceptibility to HIC.
