In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind t...In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind turbine is struck by lightning,the lightning current is directly conducted to the N-line on the low-voltage side of the box-type transformer(invasion mode of transformer synonym end).At the same time,conducted overvoltage pulse is generated in the three-phase winding on the low-voltage side,and coupled to the high-voltage side of the box-type transformer(Δconnection)to generate coupling overvoltage pulse.After investigation,the existing regulations on the tripping rate of power lines have not taken into account the impact of wind turbines being struck by lightning on line tripping,and the mechanism is still unclear.In order to further analyze the causes of lightning tripping of collection line circuit breakers in wind farms,it is necessary to study the physical process of how lightning current is conducted(coupled)to the collection line through the box-type transformer after lightning strikes on the wind turbines.In this paper,the test method of"conduction and coupling test of lightning current invading transformer N-line",and the waveform parameters(polarity,phase,amplitude,and transformation ratio)of the primary and secondary windings of the box-type transformer when lightning current invades the transformer N-line are introduced.It can provide assistance for operation and maintenance personnel to analyze the reasons for lightning tripping of 35 kV line circuit breakers in wind farms.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
In a typical process, C-Mn steel was annealed at 800℃ for 180 s, and then cooled rapidly to obtain the ferrite-martensite microstructure. After pre-straining, the specimens were baked and the corresponding bake-harde...In a typical process, C-Mn steel was annealed at 800℃ for 180 s, and then cooled rapidly to obtain the ferrite-martensite microstructure. After pre-straining, the specimens were baked and the corresponding bake-hardening （BH） values were determined as a function of pre-strain, baking temperature, and baking time. The influences ofpre-strain, baking temperature and baking time on the microstructure evolution and bake-hardening behavior of the dual-phase steel were investigated systematically. It was found that the BH value apparently increased with an increase in pre-strain in the range from 0 to 1%; however, increasing pre-strain from 1% to 8% led to a decrease in the BH value. Furthermore, an increase in baking temperature favored a gradual improvement in the BH value because of the formation of Cottrell atmosphere and the precipitation of carbides in both the ferrite and martensite phases. The BH value reached a maximum of 110 MPa at a baking temperature of 300℃. Moreover, the BH value enhanced significantly with increasing baking time from 10 to 100 min.展开更多
The purpose of this study was to investigate the suitability of palm diacylglycerol （PDAG）-enriched formulations for bakery shortening. Three types of palm diacylglycerol olein （PDAGOL） at different degree of unsa...The purpose of this study was to investigate the suitability of palm diacylglycerol （PDAG）-enriched formulations for bakery shortening. Three types of palm diacylglycerol olein （PDAGOL） at different degree of unsaturation （PDAGOL1V56, PDAGOLIV62 and PDAGOLIV64） were used as main raw materials blended with palm stearin （PS）. The blending compositions ranged from 30% to 70% of PDAGOLIV56/PS, PDAGOLIV62/PS and PDAGOLIV64/PS, respectively. The physicochemical properties of all binary blend systems were characterized for fatty acid composition （FAC）, slip melting point （SMP） and solid fat content （SFC）. The selected bakery shortening formulations were further characterised for polymorphic form of fat crystal and thermal behavior, using X-ray diffractometer （XRD） and differential scanning calorimetry （DSC）. Bakery shortening enriched with diacylglycerol that were produced from 40DS56 （40% PDAGOLIV56/60% PS）, 40DS62 （40% PDAGOL1V62/60% PS） and 40DS64 （40% PDAGOLIV64/60% PS） had 45%-50% unsaturated fatty acid and crystallized in β ＋ β polymorphs; thus they were suitable for shortening system. Based on product＇s baking performance, it could be found that all Madeira cakes prepared from bakery shortening enriched with diacylglycerol had higher specific cake volume as compared to commercial shortening （CS）. In customer acceptance test, Madeira cake made from 40DS56 shortening scored the highest rating for all sensory attributes, including overall customer acceptability. It had given an indication that 40DS56 shortening formulation was the most suitable fat blends to be used as bakery shortening.展开更多
The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Ow...The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type Structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long term wave induced bending moments are also predicted.展开更多
A box-type solar cooker with an inclined surface, equipped with a concentration reflector to allow maximum energy to be collected, enabled cooking tests to be carried out in the rainy season. Different thermocouples w...A box-type solar cooker with an inclined surface, equipped with a concentration reflector to allow maximum energy to be collected, enabled cooking tests to be carried out in the rainy season. Different thermocouples were implanted on various places of the cooker. The temperature measurements from these sensors were taken every 10 minutes.<span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The tests presented in this article relate to the preparation of eggs and rice. The absorber temperatures during the tests exceeded 100<span style="white-space:nowrap;">°</span>C. The cooking times were between 1</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">h</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">50</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">min and 2</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">h</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">20 min despite the numerous cloudy periods. The cooker made it possible to reach sufficient temperatures for healthy cooking of food. The results obtained for these first tests are satisfactory and very encouraging.</span></span></span>展开更多
The influences of high temperature pre-straining (HT-PS) on the natural aging and bake hardening of Al?Mg?Si alloys were investigated by Vickers microhardness measurements, differential scanning calorimetry (DSC) anal...The influences of high temperature pre-straining (HT-PS) on the natural aging and bake hardening of Al?Mg?Si alloys were investigated by Vickers microhardness measurements, differential scanning calorimetry (DSC) analysis and transmission electron microscopy (TEM) characterization. The results show that pre-straining at 170 °C immediately after quenching can effectively resolve the rather high T4 temper hardness caused by the conventional room temperature (RT) pre-straining treatment, and give a better bake hardening response (BHR) after paint-bake cycle. HT-PS 7% at 170 °C for 10 min is chosen as the optimum process as it provides lower T4 temper hardness and better BHR. The simultaneous introduction of dislocations and Cluster (2) can significantly suppress the natural aging and promote the precipitation of β″ phase, and reduce the effects of deformation hardening by dynamic recovery.展开更多
The effects of copper on the ageing precipitation behavior of as-quenched and pre-aged AA6016 aluminum alloy were studied by differential scanning calorimetry （DSC）, Vickers hardness measurement and transmission ele...The effects of copper on the ageing precipitation behavior of as-quenched and pre-aged AA6016 aluminum alloy were studied by differential scanning calorimetry （DSC）, Vickers hardness measurement and transmission electronic microscopy （TEM）. The results indicate that the addition of copper facilitates the growth of clusters （GP I） to the critical size during pre-ageing. Therefore, the addition of copper accelerates the transition from GP I （pre-β＂） to GP II （β＂） during final artificial ageing, and finally results in the favorable paint-bake response. However, the one with the copper level of 0.3% does not show significant baking hardening response as expected. Pre-aging can also reduce the detrimental effect due to natural aging of copper-containing alloys.展开更多
Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increas...Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increased in high-tech applications over the past decades due to their chemical, catalytic, electrical, magnetic, and optical properties. After mining, comminution and ore beneficiation, hydrometallurgical and pyrometallurgical processes are carried out to recover REE compounds. The concentrate cracking is a process wherein the structure of a REE mineral is modified in order to dissolve REE in a weak acid solution. This would be accomplished through various techniques such as alkaline cracking and acid baking. The cracked concentrate is then leached to dissolve REE in a solution and subsequently recover those via neutralization, precipitation or solvent extraction methods. This paper reviewed the cracking and leaching methods applied to REE concentrates to produce an intermediate product for further REE separation.展开更多
After 2% predeformation,the baking treatment with different schedule was carried out for low silicon TRIP steel sheet with niobium.The effects of baking temperature and time on microstructures and mechanical propertie...After 2% predeformation,the baking treatment with different schedule was carried out for low silicon TRIP steel sheet with niobium.The effects of baking temperature and time on microstructures and mechanical properties were investigated.The results showed that with increasing the baking temperature and time,the volume fraction of retained austenite decreases,and the volume fraction of tempered martensite increases; as baking temperature ranges from 80 ℃ to 170 ℃,the bake-hardening（BH）value increases obviously,while from 170 ℃ to 230 ℃,the variation of BH value is very slight; as baking time ranges from 2 min to 20 min,the BH value increases significantly,while the BH value decreases when baking time exceeds 20 min.So that when the baking temperature is 170 ℃ and the baking time is 20 min,the low silicon TRIP steel sheet exhibits good bake-hardening behavior,and the highest BH value is above 70 MPa.展开更多
Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti＋ Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstructure and texture evolution, as well as...Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti＋ Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstructure and texture evolution, as well as the morphology, size and distribution of second phase precipitates during hot rolling, cold rolling and continuous annealing were also analyzed. The results showed that the size of NbC precipitates in Ti＋Nb stabilized ultra-low-carbon bake hardened steel was smaller than that of TiC precipitates in Ti bearing ultra-low-carbon bake hardened steel, which made the average grain size of Ti＋ Nb stabilized ultra-low-carbon bake hardened steel finer than that of Ti bearing ultra-low-carbon bake hardened steel; for the yield strength, the former was higher than the latter; but for the r value which reflects the deep-drawing performance, the former was lower than the latter.展开更多
基金Supported by the Real-time Monitoring of Strong Electromagnetic Pulse Protection(Lightning)Effect and Grounding Resistance for Guangdong Yuedian Zhuhai Biqing Bay Sea Wind Farm(SFC/ZHW-ZX-FW-24-023)the Research on Key Technologies of Lightning Intelligent Protection System for Guangdong Energy Hehe Sea Wind Farm(SFC/QZW-ZX-XF-24-020).
文摘In theory,due to the fact that the grounding wire PE of wind turbine and the N-line(directly grounded)of the Y-shaped wiring on the low-voltage side of the box-type transformer share the grounding body,when the wind turbine is struck by lightning,the lightning current is directly conducted to the N-line on the low-voltage side of the box-type transformer(invasion mode of transformer synonym end).At the same time,conducted overvoltage pulse is generated in the three-phase winding on the low-voltage side,and coupled to the high-voltage side of the box-type transformer(Δconnection)to generate coupling overvoltage pulse.After investigation,the existing regulations on the tripping rate of power lines have not taken into account the impact of wind turbines being struck by lightning on line tripping,and the mechanism is still unclear.In order to further analyze the causes of lightning tripping of collection line circuit breakers in wind farms,it is necessary to study the physical process of how lightning current is conducted(coupled)to the collection line through the box-type transformer after lightning strikes on the wind turbines.In this paper,the test method of"conduction and coupling test of lightning current invading transformer N-line",and the waveform parameters(polarity,phase,amplitude,and transformation ratio)of the primary and secondary windings of the box-type transformer when lightning current invades the transformer N-line are introduced.It can provide assistance for operation and maintenance personnel to analyze the reasons for lightning tripping of 35 kV line circuit breakers in wind farms.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
基金financially supported by the National Key Project of Scientific and Technical Supporting Programs of China (No. 2011BAE13B07)
文摘In a typical process, C-Mn steel was annealed at 800℃ for 180 s, and then cooled rapidly to obtain the ferrite-martensite microstructure. After pre-straining, the specimens were baked and the corresponding bake-hardening （BH） values were determined as a function of pre-strain, baking temperature, and baking time. The influences ofpre-strain, baking temperature and baking time on the microstructure evolution and bake-hardening behavior of the dual-phase steel were investigated systematically. It was found that the BH value apparently increased with an increase in pre-strain in the range from 0 to 1%; however, increasing pre-strain from 1% to 8% led to a decrease in the BH value. Furthermore, an increase in baking temperature favored a gradual improvement in the BH value because of the formation of Cottrell atmosphere and the precipitation of carbides in both the ferrite and martensite phases. The BH value reached a maximum of 110 MPa at a baking temperature of 300℃. Moreover, the BH value enhanced significantly with increasing baking time from 10 to 100 min.
文摘The purpose of this study was to investigate the suitability of palm diacylglycerol （PDAG）-enriched formulations for bakery shortening. Three types of palm diacylglycerol olein （PDAGOL） at different degree of unsaturation （PDAGOL1V56, PDAGOLIV62 and PDAGOLIV64） were used as main raw materials blended with palm stearin （PS）. The blending compositions ranged from 30% to 70% of PDAGOLIV56/PS, PDAGOLIV62/PS and PDAGOLIV64/PS, respectively. The physicochemical properties of all binary blend systems were characterized for fatty acid composition （FAC）, slip melting point （SMP） and solid fat content （SFC）. The selected bakery shortening formulations were further characterised for polymorphic form of fat crystal and thermal behavior, using X-ray diffractometer （XRD） and differential scanning calorimetry （DSC）. Bakery shortening enriched with diacylglycerol that were produced from 40DS56 （40% PDAGOLIV56/60% PS）, 40DS62 （40% PDAGOL1V62/60% PS） and 40DS64 （40% PDAGOLIV64/60% PS） had 45%-50% unsaturated fatty acid and crystallized in β ＋ β polymorphs; thus they were suitable for shortening system. Based on product＇s baking performance, it could be found that all Madeira cakes prepared from bakery shortening enriched with diacylglycerol had higher specific cake volume as compared to commercial shortening （CS）. In customer acceptance test, Madeira cake made from 40DS56 shortening scored the highest rating for all sensory attributes, including overall customer acceptability. It had given an indication that 40DS56 shortening formulation was the most suitable fat blends to be used as bakery shortening.
基金This work was financially supported by the National Natural Science Foundation of China (Grant No. 50039010)
文摘The application of very large floating structure (VLFS) to the utilization of ocean space and exploitation of ocean resources has become one of the issues of great interest in international ocean engineering field. Owing to the advantage of simplicity in structure and low cost of construction and maintenance, box-type VLFS can be used in the calm water area near the coast as the structure configuration of floating airport. In this paper, a 3D linear hydroelastic theory is used to study the dynamic response of box-type VLFS in sinusoidal regular waves. A beam model and a 3D FEM model are respectively employed to describe the dynamic characteristics of the box-type Structure in vacuum. A hydrodynamic model (3D potential theory of flexible body) is applied to investigate the effect of different dry models on the hydroelastic response of box-type structure. Based on the calculation of hydroelastic response in regular waves, the rigid body motion displacement, flexible deflection, and the short term and long term wave induced bending moments are also predicted.
文摘A box-type solar cooker with an inclined surface, equipped with a concentration reflector to allow maximum energy to be collected, enabled cooking tests to be carried out in the rainy season. Different thermocouples were implanted on various places of the cooker. The temperature measurements from these sensors were taken every 10 minutes.<span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">The tests presented in this article relate to the preparation of eggs and rice. The absorber temperatures during the tests exceeded 100<span style="white-space:nowrap;">°</span>C. The cooking times were between 1</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">h</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">50</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">min and 2</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">h</span></span></span><span><span><span style="font-family:;" "=""> </span></span></span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">20 min despite the numerous cloudy periods. The cooker made it possible to reach sufficient temperatures for healthy cooking of food. The results obtained for these first tests are satisfactory and very encouraging.</span></span></span>
基金Project(2014DFA51270)supported by the International Science and Technology Cooperation Program of ChinaProject(51421001)supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China
文摘The influences of high temperature pre-straining (HT-PS) on the natural aging and bake hardening of Al?Mg?Si alloys were investigated by Vickers microhardness measurements, differential scanning calorimetry (DSC) analysis and transmission electron microscopy (TEM) characterization. The results show that pre-straining at 170 °C immediately after quenching can effectively resolve the rather high T4 temper hardness caused by the conventional room temperature (RT) pre-straining treatment, and give a better bake hardening response (BHR) after paint-bake cycle. HT-PS 7% at 170 °C for 10 min is chosen as the optimum process as it provides lower T4 temper hardness and better BHR. The simultaneous introduction of dislocations and Cluster (2) can significantly suppress the natural aging and promote the precipitation of β″ phase, and reduce the effects of deformation hardening by dynamic recovery.
基金Project(51105139)supported by the National Natural Science Foundation of ChinaProject(2010CB731706)supported by the National Basic Research Program of China
文摘The effects of copper on the ageing precipitation behavior of as-quenched and pre-aged AA6016 aluminum alloy were studied by differential scanning calorimetry （DSC）, Vickers hardness measurement and transmission electronic microscopy （TEM）. The results indicate that the addition of copper facilitates the growth of clusters （GP I） to the critical size during pre-ageing. Therefore, the addition of copper accelerates the transition from GP I （pre-β＂） to GP II （β＂） during final artificial ageing, and finally results in the favorable paint-bake response. However, the one with the copper level of 0.3% does not show significant baking hardening response as expected. Pre-aging can also reduce the detrimental effect due to natural aging of copper-containing alloys.
基金supported by the Research Initiation Grant of Queen’s University,Canada(#378140)Ontario Centers of Excellence VIP fund(#25394)
文摘Rare earth elements（REE） are a set of seventeen chemical elements in the periodic table, which have been found in a variety classes of minerals in the world. The global demand for REE and their compounds has increased in high-tech applications over the past decades due to their chemical, catalytic, electrical, magnetic, and optical properties. After mining, comminution and ore beneficiation, hydrometallurgical and pyrometallurgical processes are carried out to recover REE compounds. The concentrate cracking is a process wherein the structure of a REE mineral is modified in order to dissolve REE in a weak acid solution. This would be accomplished through various techniques such as alkaline cracking and acid baking. The cracked concentrate is then leached to dissolve REE in a solution and subsequently recover those via neutralization, precipitation or solvent extraction methods. This paper reviewed the cracking and leaching methods applied to REE concentrates to produce an intermediate product for further REE separation.
基金Item Sponsored by National Natural Science Foundation of China(50527402)
文摘After 2% predeformation,the baking treatment with different schedule was carried out for low silicon TRIP steel sheet with niobium.The effects of baking temperature and time on microstructures and mechanical properties were investigated.The results showed that with increasing the baking temperature and time,the volume fraction of retained austenite decreases,and the volume fraction of tempered martensite increases; as baking temperature ranges from 80 ℃ to 170 ℃,the bake-hardening（BH）value increases obviously,while from 170 ℃ to 230 ℃,the variation of BH value is very slight; as baking time ranges from 2 min to 20 min,the BH value increases significantly,while the BH value decreases when baking time exceeds 20 min.So that when the baking temperature is 170 ℃ and the baking time is 20 min,the low silicon TRIP steel sheet exhibits good bake-hardening behavior,and the highest BH value is above 70 MPa.
基金Item Sponsored by National Science and Technology Support 11th Five-Year Plan of China(2006BAE03A13)
文摘Hot rolling, cold rolling and continuous annealing processes of Ti bearing and Ti＋ Nb stabilized ultra-low-carbon bake hardened steels were experimentally studied. The microstructure and texture evolution, as well as the morphology, size and distribution of second phase precipitates during hot rolling, cold rolling and continuous annealing were also analyzed. The results showed that the size of NbC precipitates in Ti＋Nb stabilized ultra-low-carbon bake hardened steel was smaller than that of TiC precipitates in Ti bearing ultra-low-carbon bake hardened steel, which made the average grain size of Ti＋ Nb stabilized ultra-low-carbon bake hardened steel finer than that of Ti bearing ultra-low-carbon bake hardened steel; for the yield strength, the former was higher than the latter; but for the r value which reflects the deep-drawing performance, the former was lower than the latter.
