The effects of technological parameters on microstructures and properties of low cost hot rolled dual-phase steel was researched by design different finish rolling temperature,mid cooling temperature between laminar c...The effects of technological parameters on microstructures and properties of low cost hot rolled dual-phase steel was researched by design different finish rolling temperature,mid cooling temperature between laminar cooling and UFC(ultra fast cooling)and stable UFC rate on the same gauge strips with the same chemistry composition during the manufacture process.It is the key for controlling coil temperature to control finish rolling temperature and mid cooling temperature between laminar cooling and UFC that based on stable UFC rate precondition.The lower finish rolling temperature,with mid cooling temperature between laminar cooling and UFC,the better to form martensite is.The foundation of developing the similar productions on the similar product line was supplied.It is good to technological advancement of developing high affixation value production as hot rolled DP steel,TRIP steel etc.in CSP line.展开更多
The structure and texture formation for single cold rolling （SCR） with annealing and double cold rolling （DCR） with annealing were investigated based on optical microscope and X-ray diffraction （XRD） with a Nb＋...The structure and texture formation for single cold rolling （SCR） with annealing and double cold rolling （DCR） with annealing were investigated based on optical microscope and X-ray diffraction （XRD） with a Nb＋Ti bearing interstitial free （IF） steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold rolling process with the same total reduction conducted. The plastic strain ratio increases from 2.23 for single cold rolling process to 3.2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. （Ti＋Nb）C and Fe（Ti＋Nb）P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111}∥ND for the DCR annealing was higher than that for SCR annealing.展开更多
A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microseg- regation of solute elements during solidification of heat-resistant steel containing cerium was established. Then ...A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microseg- regation of solute elements during solidification of heat-resistant steel containing cerium was established. Then the model was validated by the SEM analysis of the industrial products. The type and amount of inclusions in solidifica- tion structure of 253MA heat-resistant steel were predicted by the model, and the valuable results for the inclusions controlling in 253MA steel were obtained. When the cerium addition increases, the types of inclusions transform from SiO2 and MnS to Ce2 O3 and Ce2O2 S in 253MA steel and the precipitation temperature of SiO2 and MnS decrea- ses. The inclusions CeS and CeN convert to Ce2 O3 and Ce2 O2 S as the oxygen content increases and Ce2 O3 and CeN convert to Ce2 O2 S, Ce3 S4, and MnS as the sulfur content increases. The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increa ses. There is only a small quantity of inclusions containing cerium in 253MA steel with high cleanliness, i. e. , low oxygen and sulfur contents. By contrast, a mass of SiO2 , MnS and Ce2 O2 S are formed in steel when the oxygen and sulfur contents are high enough. The condition that MnS precipitates in 253MA steel is 1.2wEo[O] ＋W[s]〉0. 01% and SiO2 precipitates when 2w[O] ＋wrs[S]〉0. 017% （W[S]0. 005%） and w[O]〉0. 006% （w[S]〉0. 005%）.展开更多
The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface react...The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve conditions for continuous casting, a new mould flux based on aluminate system was devised. The viscous properties were investigated. Scanning electron microscopy and X-ray diffraction were applied to detect and characterize the crystalline phases in the continuous cooling process. The results showed that appropriate addition of CeOcould avoid the precipitation of CaO and decrease the viscosity of the mould flux. Increasing the mass ratio of CaO /AlO, especially to a value exceeding 1, could worsen the stability of the mould flux. With a content of less than 14 wt.%, LiO could reduce the viscosity and breaking temperature, but its effect could be weakened for the promoted precipitation of LiAlO. To obtain a mould flux with stable viscous properties, such as viscosity and breaking temperature, appropriate contents of CeOand LiO should be controlled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO /AlOshould not be more than 1.展开更多
Rare earth arouses frequently international eyes in recent years.Public concern with rare earth and its usage.A TV reporter (hereinafter Reporter) interviewed two experts Prof.Yang Zhanfeng (hereinafter Yang),the depu...Rare earth arouses frequently international eyes in recent years.Public concern with rare earth and its usage.A TV reporter (hereinafter Reporter) interviewed two experts Prof.Yang Zhanfeng (hereinafter Yang),the deputy chief engineer of Baotou Iron&Steel Corporation (Group) and Prof.Yan Huizhong (hereinafter Yan),chief expert of Baotou Research Institute of Rare Earths.They introduced the current situation of Chinese rare earth industry.展开更多
文摘The effects of technological parameters on microstructures and properties of low cost hot rolled dual-phase steel was researched by design different finish rolling temperature,mid cooling temperature between laminar cooling and UFC(ultra fast cooling)and stable UFC rate on the same gauge strips with the same chemistry composition during the manufacture process.It is the key for controlling coil temperature to control finish rolling temperature and mid cooling temperature between laminar cooling and UFC that based on stable UFC rate precondition.The lower finish rolling temperature,with mid cooling temperature between laminar cooling and UFC,the better to form martensite is.The foundation of developing the similar productions on the similar product line was supplied.It is good to technological advancement of developing high affixation value production as hot rolled DP steel,TRIP steel etc.in CSP line.
基金Sponsored by National Natural Science Foundation of China(51174020)Fundamental Research Funds for Central Universities of China(FRF-SD-12-010A)
文摘The structure and texture formation for single cold rolling （SCR） with annealing and double cold rolling （DCR） with annealing were investigated based on optical microscope and X-ray diffraction （XRD） with a Nb＋Ti bearing interstitial free （IF） steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold rolling process with the same total reduction conducted. The plastic strain ratio increases from 2.23 for single cold rolling process to 3.2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. （Ti＋Nb）C and Fe（Ti＋Nb）P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111}∥ND for the DCR annealing was higher than that for SCR annealing.
基金Sponsored by National Key Basic Research Program of China(2012CB626812)National Natural Science Foundation of China(51104039)Program for New Century Excellent Talents in University of Ministry of Education of China(NCET-11-0077)
文摘A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microseg- regation of solute elements during solidification of heat-resistant steel containing cerium was established. Then the model was validated by the SEM analysis of the industrial products. The type and amount of inclusions in solidifica- tion structure of 253MA heat-resistant steel were predicted by the model, and the valuable results for the inclusions controlling in 253MA steel were obtained. When the cerium addition increases, the types of inclusions transform from SiO2 and MnS to Ce2 O3 and Ce2O2 S in 253MA steel and the precipitation temperature of SiO2 and MnS decrea- ses. The inclusions CeS and CeN convert to Ce2 O3 and Ce2 O2 S as the oxygen content increases and Ce2 O3 and CeN convert to Ce2 O2 S, Ce3 S4, and MnS as the sulfur content increases. The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increa ses. There is only a small quantity of inclusions containing cerium in 253MA steel with high cleanliness, i. e. , low oxygen and sulfur contents. By contrast, a mass of SiO2 , MnS and Ce2 O2 S are formed in steel when the oxygen and sulfur contents are high enough. The condition that MnS precipitates in 253MA steel is 1.2wEo[O] ＋W[s]〉0. 01% and SiO2 precipitates when 2w[O] ＋wrs[S]〉0. 017% （W[S]0. 005%） and w[O]〉0. 006% （w[S]〉0. 005%）.
基金supported by the National Natural Science Foundation of China(51374059,51304042)the Fundamental Research Funds for the Central Universities of China(N130402020)the Key Science and Technology Program of Liaoning Province(2012221013)
文摘The conventional mould fluxes can not be applied to the continuous casting of RE alloyed heat resistant steel, because severe slag-metal interface reactions occur generally in the mold. To restrain the interface reaction and improve conditions for continuous casting, a new mould flux based on aluminate system was devised. The viscous properties were investigated. Scanning electron microscopy and X-ray diffraction were applied to detect and characterize the crystalline phases in the continuous cooling process. The results showed that appropriate addition of CeOcould avoid the precipitation of CaO and decrease the viscosity of the mould flux. Increasing the mass ratio of CaO /AlO, especially to a value exceeding 1, could worsen the stability of the mould flux. With a content of less than 14 wt.%, LiO could reduce the viscosity and breaking temperature, but its effect could be weakened for the promoted precipitation of LiAlO. To obtain a mould flux with stable viscous properties, such as viscosity and breaking temperature, appropriate contents of CeOand LiO should be controlled to around 10 wt.% and 14 wt.%, while the mass ratio of CaO /AlOshould not be more than 1.
文摘Rare earth arouses frequently international eyes in recent years.Public concern with rare earth and its usage.A TV reporter (hereinafter Reporter) interviewed two experts Prof.Yang Zhanfeng (hereinafter Yang),the deputy chief engineer of Baotou Iron&Steel Corporation (Group) and Prof.Yan Huizhong (hereinafter Yan),chief expert of Baotou Research Institute of Rare Earths.They introduced the current situation of Chinese rare earth industry.
