Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat tre...Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat treatment parameters that could ensure improved toughness and ductility. Determining the optimum annealing parameters ensures valued recrystallization and also minimizes grain growth that could be detrimental to the resulting product. 40% and 55% cold drawn steels were annealed at temperatures 500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval of 10 minutes to identify the temperature range and soaking time where optimum combination of properties could be obtained. Tensile test and impact toughness experiments were done to determine the required properties of the steel. Polynomial regression analysis was used to fit the properties relationship with soaking time and temperatures and the classical optimization technique was used to determine the minimum soaking time and temperature required for improved properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain size of 44.7 mm can be considered to be the optimum annealing treatment for the 40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.展开更多
It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high dens...It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high density of dislocations emerges at the Fe_3C/Fe interface. Furthermore,there are some evidences to support that dislocation cuts through Fe_3C.There- fore,it is necessary to consider the contribution of cementite being sheared strengthening.展开更多
The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% de...The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.展开更多
Commercial grade-70 tire cord steel was microalloyed with V and N to explore the possibility of substitu- ting V for C and the effect of V and N on cementite dissolution during cold drawing process. Tensile strength, ...Commercial grade-70 tire cord steel was microalloyed with V and N to explore the possibility of substitu- ting V for C and the effect of V and N on cementite dissolution during cold drawing process. Tensile strength, elon- gation and torsion laps of cold-drawn wires were determined. Microstructures of secondary phases were studied by transmission electron microscopy （TEM） and energy dispersive spectroscopy （EDS）. Saturation magnetization was measured by using a vibrating sample magnetometer （VSM） to evaluate cementite dissolution during cold drawing process. Experimental results showed that with the increase of V content, tensile strength increased, elongation slightly decreased, and the torsion laps of the cold-drawn wires decreased. Results also showed that with the increase of N content, a peak （increasing first and then decreasing） appeared in the tensile strength graph, and an increase of elongation and a decrease of torsion laps of the cold-drawn wires occured. N is soluble in ferrite when its content is low. The increase in the content of N to 82 × 10^-6 will result in the precipitation of the V-containing secondary pha- ses. Also, cementite tended to be stable during cold drawing process with the increase of V and N contents. Grade-80 tire cord steel can be replaced by grade 70 tire cord steel microalloyed with 0. 086 mass% V.展开更多
Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied thr...Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied through X-ray diffraction. The results indicate that a strong intensity of {114}<110> was formed in the continuous annealing steel and a strong intensity of {111}<112> was formed in the batch annealing steel; not only that but the γ fiber slowly rotated to the low angel α fiber with the angel being about 30° nearly {112}<110>texture owing to the higher second reduction.展开更多
Low carbon steel metal is used for the manufacture of nails. Steel wire with <0.3% C content is cold-drawn through a series of drawing dies to reduce the diameter of the wire to the required diameter of the nails. ...Low carbon steel metal is used for the manufacture of nails. Steel wire with <0.3% C content is cold-drawn through a series of drawing dies to reduce the diameter of the wire to the required diameter of the nails. A 0.12%w C steel wire cold drawn progressively by 20%, 25%, 40% and 50% was investigated. The influence of the degree of cold drawing on the mechanical properties of the carbon steel material were studied using the tensile test, impact test and hardness test experiments in order to replicate the service condition of the nails. The tensile test was done on a Montanso? tensometer to investigate the yield strength and the tensile strength of the material as the degree of deformation increases. An Izod test was used to determine the impact toughness of the steel using the Hounsfield impact machine and the hardness numbers were obtained for the different degrees of drawn deformation of the steel on the Brinnel tester. The study used the stress-strain relationship of the tensile test experiment to study the effect of the degree of cold-drawing deformation on the yield strength and tensile strength properties of the low carbon steel. The yield strength of the material was observed to reduce with increasing degree of cold-drawing, an indication of reduction in the ductility and the tensile strength of the material reduced with increasing degree of cold-drawn deformation. The ability of the material to resist impact loads when nails are hammered reduced with increasing degree of drawn deformation as a result of strain hardening of the material after the drawing operation. However the resilience of the material to further cold drawn deformation increased with increasing degree of deformation as evident in the Brinnel hardness number which increases with the degree of drawing deformation. This is an indication of the material’s approach to brittleness as the degree of drawn deformation increases.展开更多
该研究系统探究了脉冲电场(pulsed electric field,PEF)处理对冷萃绿茶中挥发性化合物及其在低温贮藏下稳定性的影响。对比PEF处理、高温短时间(high temperature short time,HTST)处理对冷萃绿茶贮藏期间香气的影响,通过顶空固相微萃取...该研究系统探究了脉冲电场(pulsed electric field,PEF)处理对冷萃绿茶中挥发性化合物及其在低温贮藏下稳定性的影响。对比PEF处理、高温短时间(high temperature short time,HTST)处理对冷萃绿茶贮藏期间香气的影响,通过顶空固相微萃取-气相-飞行时间质谱鉴定挥发性化合物,PEF处理组、HTST处理组和对照组分别检出90、78、75种化合物。分析各类化合物浓度发现,PEF处理与对照组相比,使酮类、酯类及含氮杂环物质的浓度分别增加39.67%、267.92%、101.29%,赋予茶汤丰富的香气特征。同时,PEF处理相较于HTST处理更好地保留了冷萃绿茶中的醇类、醛类、萜烯类化合物。正交偏最小二乘判别分析(R 2X=0.636,R 2Y=0.995,Q 2=0.926)筛选出变量投影值>1的化合物共42个,其中PEF处理组中包括特征性酯类化合物[异戊酸叶醇酯、(E)-2-己烯基己酸酯、γ-己内酯]、HTST处理组中包括特征性酚类化合物(丁香酚、苯酚)和吡嗪。相对气味活度值(relative odour activity value,ROAV)分析表明,PEF处理组中ROAV>1的化合物有15种,而HTST处理组和对照组仅为12和11种,表明PEF处理后的冷萃绿茶具有更加丰富的香气感知。感官评价发现PEF处理后的冷萃绿茶相较于HTST处理组具有更高的花香、青草香、果香感知,且香气总体强度更高。通过拟合Weibull分布函数比较PEF处理和HTST处理对主要香气贮藏稳定性的影响,PEF处理具有更好的香气贮藏稳定性,尤其是对芳樟醇的香气保留(ROAV>1)超76 d。研究结果表明,PEF作为非热杀菌技术,可有效保持冷萃绿茶的特征香气轮廓,提高香气贮藏稳定性,为高品质热敏性饮料的贮藏保鲜提供了理论依据与技术支撑。展开更多
针对油缸用无缝钢管的服役条件等,运用Nb微合金化设计了E355+N的化学成分和“150tKR→150tBOF→150tLF→150tRH→CC(Φ310 mm)→管坯加热→穿孔→轧管→定径(Φ194×19 mm)→冷却→正火→矫直→探伤→检验→包装”的无缝钢管生产工...针对油缸用无缝钢管的服役条件等,运用Nb微合金化设计了E355+N的化学成分和“150tKR→150tBOF→150tLF→150tRH→CC(Φ310 mm)→管坯加热→穿孔→轧管→定径(Φ194×19 mm)→冷却→正火→矫直→探伤→检验→包装”的无缝钢管生产工艺路线。通过生产试制成功研发了Nb微合金化E355+N油缸用管,结果表明:含0.03%Nb的E355+N(欧标非合金结构钢)热轧后经900~920℃正火,与不含Nb正火的Q345D(国标低合金高强度钢)比较其平均伸长率提高了约13%,-20℃冲击性能平均值提高约10%,并且其冲击性能更加稳定。试制的无缝钢管化学成分均匀、有害杂质元素少、钢纯净度高,钢管的晶粒细小、组织均匀,客户后续刮削滚压(SRB:Scraping and Rolling Processing)加工后无“白斑”等缺陷,具有较好的加工性能。制造的油缸用产品质量稳定,实现批量供应,成功替代进口。展开更多
文摘Drawn low carbon steel is characterized by brittle fracture. These defects are associated with the poor ductility and high strain hardening due to the cold work. There is a need therefore to determine optimum heat treatment parameters that could ensure improved toughness and ductility. Determining the optimum annealing parameters ensures valued recrystallization and also minimizes grain growth that could be detrimental to the resulting product. 40% and 55% cold drawn steels were annealed at temperatures 500℃ to 650℃ at intervals of 50℃ and soaked for 10 to 60 minutes at interval of 10 minutes to identify the temperature range and soaking time where optimum combination of properties could be obtained. Tensile test and impact toughness experiments were done to determine the required properties of the steel. Polynomial regression analysis was used to fit the properties relationship with soaking time and temperatures and the classical optimization technique was used to determine the minimum soaking time and temperature required for improved properties of the steel. Annealing treatment at 588℃ for 11 minutes at grain size of 44.7 mm can be considered to be the optimum annealing treatment for the 40% cold drawn 0.12 wt% C steel and 539℃ for 17 minutes at grain size of 19.5 mm for the 55% cold drawn 0.12 wt% C steel.
文摘It was shown by the study of TEM that the fine lamellar pearlite becomes a ductile phase dur- ing cold drawing.There exist many ledges to emit dislocations at Fe_3C/Fe interface.It is one of the reasons that high density of dislocations emerges at the Fe_3C/Fe interface. Furthermore,there are some evidences to support that dislocation cuts through Fe_3C.There- fore,it is necessary to consider the contribution of cementite being sheared strengthening.
文摘The paper presents the results of investigation on the effect of soaking time on the yield strength, ductility and hardness properties of annealed cold-drawn low carbon steel. The low carbon steel cold-drawn at 40% deformation was annealed at 900 deg Celsius for soaking times of 10, 20, 30, 40, 50 and 60 minutes. Tensile, charpy and Brinnel hardness tests were conducted to determine the yield strengths, tensile strengths, impact strengths, ductility and hardness of the annealed steel with increasing soaking time. The yield strength, tensile strength, hardness and impact strength of the steel showed a continuous drop in value with increasing soaking time up to 60 minutes with a steep drop between 30 and 40 minutes. Ductility values followed the same decreasing trend up to 40 minutes soaking time after which the values started increasing again till 60 minutes soaking time. There was a linear relationship between the tensile strength and hardness of the material for different soaking times. This linear relationship was also observed for yield strength and hardness of the material.
基金Sponsored by Natural Science Foundation of Hubei Province of China(2014CFB801)
文摘Commercial grade-70 tire cord steel was microalloyed with V and N to explore the possibility of substitu- ting V for C and the effect of V and N on cementite dissolution during cold drawing process. Tensile strength, elon- gation and torsion laps of cold-drawn wires were determined. Microstructures of secondary phases were studied by transmission electron microscopy （TEM） and energy dispersive spectroscopy （EDS）. Saturation magnetization was measured by using a vibrating sample magnetometer （VSM） to evaluate cementite dissolution during cold drawing process. Experimental results showed that with the increase of V content, tensile strength increased, elongation slightly decreased, and the torsion laps of the cold-drawn wires decreased. Results also showed that with the increase of N content, a peak （increasing first and then decreasing） appeared in the tensile strength graph, and an increase of elongation and a decrease of torsion laps of the cold-drawn wires occured. N is soluble in ferrite when its content is low. The increase in the content of N to 82 × 10^-6 will result in the precipitation of the V-containing secondary pha- ses. Also, cementite tended to be stable during cold drawing process with the increase of V and N contents. Grade-80 tire cord steel can be replaced by grade 70 tire cord steel microalloyed with 0. 086 mass% V.
基金Sponsored by the National Natural Science Foundation of China(Grant No.U1460101)
文摘Two double cold reduction-drawn and redrawn(DRD) tinplate steels of the same chemistries that have been processed by continuous and batch annealing line have been researched. The composition of fibers were studied through X-ray diffraction. The results indicate that a strong intensity of {114}<110> was formed in the continuous annealing steel and a strong intensity of {111}<112> was formed in the batch annealing steel; not only that but the γ fiber slowly rotated to the low angel α fiber with the angel being about 30° nearly {112}<110>texture owing to the higher second reduction.
文摘Low carbon steel metal is used for the manufacture of nails. Steel wire with <0.3% C content is cold-drawn through a series of drawing dies to reduce the diameter of the wire to the required diameter of the nails. A 0.12%w C steel wire cold drawn progressively by 20%, 25%, 40% and 50% was investigated. The influence of the degree of cold drawing on the mechanical properties of the carbon steel material were studied using the tensile test, impact test and hardness test experiments in order to replicate the service condition of the nails. The tensile test was done on a Montanso? tensometer to investigate the yield strength and the tensile strength of the material as the degree of deformation increases. An Izod test was used to determine the impact toughness of the steel using the Hounsfield impact machine and the hardness numbers were obtained for the different degrees of drawn deformation of the steel on the Brinnel tester. The study used the stress-strain relationship of the tensile test experiment to study the effect of the degree of cold-drawing deformation on the yield strength and tensile strength properties of the low carbon steel. The yield strength of the material was observed to reduce with increasing degree of cold-drawing, an indication of reduction in the ductility and the tensile strength of the material reduced with increasing degree of cold-drawn deformation. The ability of the material to resist impact loads when nails are hammered reduced with increasing degree of drawn deformation as a result of strain hardening of the material after the drawing operation. However the resilience of the material to further cold drawn deformation increased with increasing degree of deformation as evident in the Brinnel hardness number which increases with the degree of drawing deformation. This is an indication of the material’s approach to brittleness as the degree of drawn deformation increases.
文摘该研究系统探究了脉冲电场(pulsed electric field,PEF)处理对冷萃绿茶中挥发性化合物及其在低温贮藏下稳定性的影响。对比PEF处理、高温短时间(high temperature short time,HTST)处理对冷萃绿茶贮藏期间香气的影响,通过顶空固相微萃取-气相-飞行时间质谱鉴定挥发性化合物,PEF处理组、HTST处理组和对照组分别检出90、78、75种化合物。分析各类化合物浓度发现,PEF处理与对照组相比,使酮类、酯类及含氮杂环物质的浓度分别增加39.67%、267.92%、101.29%,赋予茶汤丰富的香气特征。同时,PEF处理相较于HTST处理更好地保留了冷萃绿茶中的醇类、醛类、萜烯类化合物。正交偏最小二乘判别分析(R 2X=0.636,R 2Y=0.995,Q 2=0.926)筛选出变量投影值>1的化合物共42个,其中PEF处理组中包括特征性酯类化合物[异戊酸叶醇酯、(E)-2-己烯基己酸酯、γ-己内酯]、HTST处理组中包括特征性酚类化合物(丁香酚、苯酚)和吡嗪。相对气味活度值(relative odour activity value,ROAV)分析表明,PEF处理组中ROAV>1的化合物有15种,而HTST处理组和对照组仅为12和11种,表明PEF处理后的冷萃绿茶具有更加丰富的香气感知。感官评价发现PEF处理后的冷萃绿茶相较于HTST处理组具有更高的花香、青草香、果香感知,且香气总体强度更高。通过拟合Weibull分布函数比较PEF处理和HTST处理对主要香气贮藏稳定性的影响,PEF处理具有更好的香气贮藏稳定性,尤其是对芳樟醇的香气保留(ROAV>1)超76 d。研究结果表明,PEF作为非热杀菌技术,可有效保持冷萃绿茶的特征香气轮廓,提高香气贮藏稳定性,为高品质热敏性饮料的贮藏保鲜提供了理论依据与技术支撑。
文摘针对油缸用无缝钢管的服役条件等,运用Nb微合金化设计了E355+N的化学成分和“150tKR→150tBOF→150tLF→150tRH→CC(Φ310 mm)→管坯加热→穿孔→轧管→定径(Φ194×19 mm)→冷却→正火→矫直→探伤→检验→包装”的无缝钢管生产工艺路线。通过生产试制成功研发了Nb微合金化E355+N油缸用管,结果表明:含0.03%Nb的E355+N(欧标非合金结构钢)热轧后经900~920℃正火,与不含Nb正火的Q345D(国标低合金高强度钢)比较其平均伸长率提高了约13%,-20℃冲击性能平均值提高约10%,并且其冲击性能更加稳定。试制的无缝钢管化学成分均匀、有害杂质元素少、钢纯净度高,钢管的晶粒细小、组织均匀,客户后续刮削滚压(SRB:Scraping and Rolling Processing)加工后无“白斑”等缺陷,具有较好的加工性能。制造的油缸用产品质量稳定,实现批量供应,成功替代进口。
