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
The evolution of microstructure and texture for drawn polycrystalline Ag was investigated by transmission electron microscopy and electron backscattering diffraction.The results show that there are deformation twins a...The evolution of microstructure and texture for drawn polycrystalline Ag was investigated by transmission electron microscopy and electron backscattering diffraction.The results show that there are deformation twins and some un-tangled discrete dislocations at low strains.When the strain is increased to 0.58,a lot of high density dislocation walls and microbands come into being.At the same time,some twins lose the twinning relationship of 60°<111>.At a strain of 0.94,both dislocation boundaries and twin boundaries will rotate to the axis direction of wires and the shear bands start to appear.When the strain is higher than 1.96,most of the boundaries are parallel to the drawn direction.Texture analysis indicates that with the strain increasing,the volume fraction of complex texture component decreases,but<111>and<100>texture components increase.However,the variation in the volume fraction of each texture component as strains is not evident when the strains are higher than 0.58.For polycrystalline Ag with low stacking fault energy,complex texture components are easily formed.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supported by the National Natural Science Foundation of China(Grant Nos.51471123,51171135)the Natural Science Foundation of Shaanxi Province(Grant Nos.2012K07-08,2013KJXX-61)the Industrialization Program of Shaanxi Province(Grant No.2013JC14)
文摘The evolution of microstructure and texture for drawn polycrystalline Ag was investigated by transmission electron microscopy and electron backscattering diffraction.The results show that there are deformation twins and some un-tangled discrete dislocations at low strains.When the strain is increased to 0.58,a lot of high density dislocation walls and microbands come into being.At the same time,some twins lose the twinning relationship of 60°<111>.At a strain of 0.94,both dislocation boundaries and twin boundaries will rotate to the axis direction of wires and the shear bands start to appear.When the strain is higher than 1.96,most of the boundaries are parallel to the drawn direction.Texture analysis indicates that with the strain increasing,the volume fraction of complex texture component decreases,but<111>and<100>texture components increase.However,the variation in the volume fraction of each texture component as strains is not evident when the strains are higher than 0.58.For polycrystalline Ag with low stacking fault energy,complex texture components are easily formed.
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。
