This paper introduces the research and development of high strength A517Q developed by Baosteel for platform rack,with micro-alloying adding suitable quenching and tempering process,trial thickness of 127 - 178 mm hig...This paper introduces the research and development of high strength A517Q developed by Baosteel for platform rack,with micro-alloying adding suitable quenching and tempering process,trial thickness of 127 - 178 mm high-strength A517Q.The trial plate crossing thickness has a uniform mechanical properties, yield strength greater than 700 MPa,tensile strength than 790 MPa,the Charpy impact than 90 J at -40℃, aging impact than 69 J,has high strength and excellent low temperature impact toughness,While the plate has excellent resistance to crack tearing ability of low-temperature,NDT is less than -45℃.The Developing heavy plates had been used for manufacturing racks of 200-foot jack-up offshore platform,the performance meeting the requirements of the ABS,CCS classification societies.展开更多
We investigated phase transition and precipitation of ultra-high strength steel（UHSS）in a new ＂short process＂ with controlled rolling and controlled cooling.Thermalexpansion test combined with metallographic obser...We investigated phase transition and precipitation of ultra-high strength steel（UHSS）in a new ＂short process＂ with controlled rolling and controlled cooling.Thermalexpansion test combined with metallographic observation was used to research the continuous cooling transformation（CCT）curve.Moreover,the microstructuraltransformation and precipitation law was revealed by morphologicalobservation and alloying elements by electron probe micro-analyzer（EPMA）.Transmission electron microscopy（TEM）was utilized to analyze the composition and grain orientation of microstructure.The study showed that the measured criticaltransformation temperatures of Ac1 and Ac3 were 746 and 868 ℃,respectively.The CCT curve indicated that the undercooled austenite was transformed into proeutectoid ferrite and bainite with HV 520 in a broad range of cooling rate 0.1^（-1） ℃·s^（-1）.When subjected to a cooling rate of 1 ℃·s^（-1）,the undercooled austenite was divided into small-sized blocks by formed martensite.With further increase of cooling rate,micro-hardness increased dramatically,the microstructure of specimen was mainly lathe bainite（LB）,granular bainite（GB）,lath martensite（LM）and residualaustenite.By diffraction test analysis,it was identified that there was K-S orientation relationship between martensite and austenite for {110}_α//{111}_γ,{111}_α//{101}_γ.EPMA clearly showed that carbon diffused adequately due to staying for a long time at high temperature with a lower cooling rate of 2 ℃·s-1.Phase transition drive force was lower and the residualaustenite existed in the block form of Martensite austenite island（M-A）.With the increase of cooling rate to 10 ℃·s^（-1）,the block residualaustenite reduced,the carbon content of residualaustenite increased and α phase around the residualaustenite formed into a low carbon bainite form.展开更多
Analyzed and studied the characters of high strength low alloy steel which contain Mo,Cr,Nb and Ni.etc.Following actual rolling,combining the feature of rolling mode,and exploiting the equipment advantage of 5 m Heavy...Analyzed and studied the characters of high strength low alloy steel which contain Mo,Cr,Nb and Ni.etc.Following actual rolling,combining the feature of rolling mode,and exploiting the equipment advantage of 5 m Heavy Plate Mill,optimized the material design,heating temperature and rolling method, stabilized rolling process of thin alloyed steel,the quality index was advanced.展开更多
Systematic research on developing a series of extra high strength steel plates for shipbuilding via thermomechanical control process (TMCP) is introduced.A microalloyed low carbon-equivalent SiMnCrNiCu steel was used ...Systematic research on developing a series of extra high strength steel plates for shipbuilding via thermomechanical control process (TMCP) is introduced.A microalloyed low carbon-equivalent SiMnCrNiCu steel was used to develop F460 steel.Ultra low carbon Cu-Ni containing steels were used to develop NV-F550,NV-F620 and NV-F690 steel plates.The effect of TMCP parameters on microstructure and properties was investigated by test-scale plant trials.Industrial production trials were conducted to verify the validity of the laboratory studies on the F460 steel.Heavy plates in 45-60 mm thickness met Det Norske Veritas NV-F460 specification.The effect of heat-input on the mechanical properties of the coarse-grained-heat-affect-zone (CGHAZ) of the advanced heavy plates was studied.展开更多
文摘This paper introduces the research and development of high strength A517Q developed by Baosteel for platform rack,with micro-alloying adding suitable quenching and tempering process,trial thickness of 127 - 178 mm high-strength A517Q.The trial plate crossing thickness has a uniform mechanical properties, yield strength greater than 700 MPa,tensile strength than 790 MPa,the Charpy impact than 90 J at -40℃, aging impact than 69 J,has high strength and excellent low temperature impact toughness,While the plate has excellent resistance to crack tearing ability of low-temperature,NDT is less than -45℃.The Developing heavy plates had been used for manufacturing racks of 200-foot jack-up offshore platform,the performance meeting the requirements of the ABS,CCS classification societies.
基金Funded by the Scientifi c and Technological Research Program of Chongqing Municipal Education Commission(No.KJ1501324)the General Project of Chongqing Frontier and Applied Basic Research Project(No.cstc2015jcyj A90005)the Research Foundation of Chongqing University of Science and Technology(Nos.CK2013Z16&CK2014Z20)
文摘We investigated phase transition and precipitation of ultra-high strength steel（UHSS）in a new ＂short process＂ with controlled rolling and controlled cooling.Thermalexpansion test combined with metallographic observation was used to research the continuous cooling transformation（CCT）curve.Moreover,the microstructuraltransformation and precipitation law was revealed by morphologicalobservation and alloying elements by electron probe micro-analyzer（EPMA）.Transmission electron microscopy（TEM）was utilized to analyze the composition and grain orientation of microstructure.The study showed that the measured criticaltransformation temperatures of Ac1 and Ac3 were 746 and 868 ℃,respectively.The CCT curve indicated that the undercooled austenite was transformed into proeutectoid ferrite and bainite with HV 520 in a broad range of cooling rate 0.1^（-1） ℃·s^（-1）.When subjected to a cooling rate of 1 ℃·s^（-1）,the undercooled austenite was divided into small-sized blocks by formed martensite.With further increase of cooling rate,micro-hardness increased dramatically,the microstructure of specimen was mainly lathe bainite（LB）,granular bainite（GB）,lath martensite（LM）and residualaustenite.By diffraction test analysis,it was identified that there was K-S orientation relationship between martensite and austenite for {110}_α//{111}_γ,{111}_α//{101}_γ.EPMA clearly showed that carbon diffused adequately due to staying for a long time at high temperature with a lower cooling rate of 2 ℃·s-1.Phase transition drive force was lower and the residualaustenite existed in the block form of Martensite austenite island（M-A）.With the increase of cooling rate to 10 ℃·s^（-1）,the block residualaustenite reduced,the carbon content of residualaustenite increased and α phase around the residualaustenite formed into a low carbon bainite form.
文摘Analyzed and studied the characters of high strength low alloy steel which contain Mo,Cr,Nb and Ni.etc.Following actual rolling,combining the feature of rolling mode,and exploiting the equipment advantage of 5 m Heavy Plate Mill,optimized the material design,heating temperature and rolling method, stabilized rolling process of thin alloyed steel,the quality index was advanced.
文摘Systematic research on developing a series of extra high strength steel plates for shipbuilding via thermomechanical control process (TMCP) is introduced.A microalloyed low carbon-equivalent SiMnCrNiCu steel was used to develop F460 steel.Ultra low carbon Cu-Ni containing steels were used to develop NV-F550,NV-F620 and NV-F690 steel plates.The effect of TMCP parameters on microstructure and properties was investigated by test-scale plant trials.Industrial production trials were conducted to verify the validity of the laboratory studies on the F460 steel.Heavy plates in 45-60 mm thickness met Det Norske Veritas NV-F460 specification.The effect of heat-input on the mechanical properties of the coarse-grained-heat-affect-zone (CGHAZ) of the advanced heavy plates was studied.
