Fabrication of PVDF films has been making using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of temperature fabrication on electri...Fabrication of PVDF films has been making using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of temperature fabrication on electrical properties and crystallite size of PVDF films. The electrical properties like as surface resistivity are discussion focus in this paper. Surface resistivity properties of PVDF can be improved by mechanical treatment on the varying film thickness and the temperature. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Crystallite size of PVDF films calculate from broadening pattern of X-Ray Diffraction. Furthermore, from the diffraction pattern calculated β fraction and crystallite size, for calculation to determine the crystallite size of the sample by using the Scherrer equation. Has been obtained an increase piezoelectric properties of PVDF films that characterized by increasing β fraction. Have been obtained β fraction increased from 25.4% up to 44% for temperatures of 130°C up to 170°C, respectively. Resistivity value has been obtained at temperature 130°C up to 170°C, decreased from 1.23 × 104 Wm up to 0.21 × 104 Wm respectively. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130°C up to 170°C respectively are increased from 7.2 nm up to 20.54 nm. These results indicate that mechanical treatment caused increase β fraction and decrease surface resistivity. Increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases.展开更多
The thermoplasticity of duplex stainless steel 2205（DSS2205） is better than that of lean duplex steel 2101（LDX2101）, which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase rat...The thermoplasticity of duplex stainless steel 2205（DSS2205） is better than that of lean duplex steel 2101（LDX2101）, which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy（OM）, electron backscatter diffraction（EBSD）, Thermo-Calc software, and transmission electron microscopy（TEM）. The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.展开更多
The recrystallization kinetics and grain size models were developed for the C Mn and niobium containing steels to describe the metallurgical phenomenon such as softening, grain growth, and strain accumulation. Based o...The recrystallization kinetics and grain size models were developed for the C Mn and niobium containing steels to describe the metallurgical phenomenon such as softening, grain growth, and strain accumulation. Based on the recrystallization kinetics equations, the mean flow stress and the rolling load of each pass were predicted and the optimum rolling schedule was proposed for hot strip rolling. The austenite grain refinement is associated with the addition of niobium, the decrease of starting temperature of finish rolling, and the reduction of finished thickness. The mean flow stress curve with a continuous rising characteristic can be usually observed in the finish rolling of niobium containing steel, which is formed as a result of the heavy incomplete softening and strain accumulation. The predic ted rolling loads are in good agreement with the measured ones.展开更多
An integrated metallurgical model was developed for Nb steels to predict the microstructure evolution and mechanical properties during the hot-strip rolling and cooling process. On the basis of the industrial data, th...An integrated metallurgical model was developed for Nb steels to predict the microstructure evolution and mechanical properties during the hot-strip rolling and cooling process. On the basis of the industrial data, the transformation kinetics, strength, and elongation rate were evaluated for different chemical compositions and processing parameters. The yield strength and tensile strength increase with increasing Nb content or decreasing finishing temperature. The bainite distributed in finer ferrite matrix, which is produced at relatively low coiling temperatures, can greatly increase the strength of steel, especially tensile strength, thereby decreasing the yield ratio. A reasonable agreement was found between the predicted and measured results. It indicates that the present models can be used to simulate the actual production process.展开更多
Microstructures and properties of three Nb micro-alloyed steels were studied through hot rolling experiment. The result indicates that the ferrite grain size （dF ） decreases with increasing Nb content （Nb）, and th...Microstructures and properties of three Nb micro-alloyed steels were studied through hot rolling experiment. The result indicates that the ferrite grain size （dF ） decreases with increasing Nb content （Nb）, and the bainite fraction （fB） increases with increasing Nb content （Nb）. The effect of ferrite grain size （dF） on yield strength （δy） is related to Nb content （Nb）, and the effect of bainite fraction （fB） on yield strength （δy） is unrelated to Nb content （Nb）. Modelling of yield strength （δy） for Nb micro-alloyed steels with high accuracy has been built up with Nb content （Nb） and bainite fraction （fB） taken into account as new parameters, and formulas for ferrite grain size （dF ） and bainite fraction （fB） vs Nb content （Nb） have also been established under the experiment conditions. The research results could provide instructions for industrial productions.展开更多
Average grain size and grain size distribution in as hot-rolled SPHC, SPHD, and SPHE sheets manufac- tured by compact strip production （CSP） processing and traditional continuous casting and rolling （CCR） processi...Average grain size and grain size distribution in as hot-rolled SPHC, SPHD, and SPHE sheets manufac- tured by compact strip production （CSP） processing and traditional continuous casting and rolling （CCR） processing respectively were investigated by quantitative metallographic method. The results show that the average grain size and distribution width of grain size in sheets manufactured by CSP processing was obviously larger than that by CCR processing. It was analyzed that multi-phase transformation and high reduction ratio in CCR processing resulted in refining grain size, which would be dominant reason for controlling grain size. In plain carbon steels such as SPHC, SPHD and SPHE, the effect of fine precipitation in CSP on behavior of deformation and recrystallization of austenite during roiling, and consequent refinement of grain size seem not to be as important as the effect of reheating and roughing in CCR processing. Homogenizing in reheating and refining grain size in roughing in CCR processing would refine final grain size and also make grain size homogenized, Very coarse grain size would result in mixed grain size, large distribution width of grain size due to interaction of static and dynamic recrystallization in CSP processing展开更多
A new Ti-V-Mo complex microalloyed hot-rolled high-strength steel sheet was developed by controlling a thermo-mechanical controlled processing （TMCP） schedule, in particular with variants in coiling temperature. The...A new Ti-V-Mo complex microalloyed hot-rolled high-strength steel sheet was developed by controlling a thermo-mechanical controlled processing （TMCP） schedule, in particular with variants in coiling temperature. The effects of coiling temperature （CT） on various hardening mechanisms and mechanical properties of Ti-V-Mo complex mi- croalloyed high-strength low-alloy steels were investigated. The results revealed that the steels are mainly strengthened by a combined effect of ferrite grain refinement hardening and precipitation hardening. The variation in simulated coiling temperature causes a significant difference in strength, which is mainly attributed to different precipitation hardening increment contributions. When the CT is 600 ℃, the experimental steel has the best mechanical properties： ultimate tensile strength （UTS） 1000 MPa, yield strength （YS） 955 MPa and elongation （EL） 17%. Moreover, about 82 wt% of the total precipitates are nano-sized carbide particles with diameter of 1-10 nm, which is randomly dispersed in the ferrite matrix. The nano-sized carbide particles led to a strong precipitation hardening increment up to 310 MPa.展开更多
文摘Fabrication of PVDF films has been making using Hot Roll Press. Preparation of samples carried out for nine different temperatures. This condition is carried out to see the effect of temperature fabrication on electrical properties and crystallite size of PVDF films. The electrical properties like as surface resistivity are discussion focus in this paper. Surface resistivity properties of PVDF can be improved by mechanical treatment on the varying film thickness and the temperature. To obtain the diffraction pattern of sample characterization is performed using X-Ray Diffraction. Crystallite size of PVDF films calculate from broadening pattern of X-Ray Diffraction. Furthermore, from the diffraction pattern calculated β fraction and crystallite size, for calculation to determine the crystallite size of the sample by using the Scherrer equation. Has been obtained an increase piezoelectric properties of PVDF films that characterized by increasing β fraction. Have been obtained β fraction increased from 25.4% up to 44% for temperatures of 130°C up to 170°C, respectively. Resistivity value has been obtained at temperature 130°C up to 170°C, decreased from 1.23 × 104 Wm up to 0.21 × 104 Wm respectively. From the experimental results and the calculation of crystallite sizes obtained for the samples with temperature 130°C up to 170°C respectively are increased from 7.2 nm up to 20.54 nm. These results indicate that mechanical treatment caused increase β fraction and decrease surface resistivity. Increasing temperatures will also increase the size of the crystallite of the sample. This happens because with the increasing temperature causes the higher the degree of crystallization of PVDF film sample is formed, so that the crystallite size also increases.
基金financially supported by the National Natural Science Foundation of China (No. 51174026)the National Science and Technology Pillar Program during the Twelfth Five-Year Plan Period (No. 2012BAE04B02)
文摘The thermoplasticity of duplex stainless steel 2205（DSS2205） is better than that of lean duplex steel 2101（LDX2101）, which undergoes severe cracking during hot rolling. The microstructure, microhardness, phase ratio, and recrystallization dependence of the deformation compatibility of LDX2101 and DSS2205 were investigated using optical microscopy（OM）, electron backscatter diffraction（EBSD）, Thermo-Calc software, and transmission electron microscopy（TEM）. The results showed that the phase-ratio transformations of LDX2101 and DSS2205 were almost equal under the condition of increasing solution temperature. Thus, the phase transformation was not the main cause for the hot plasticity difference of these two steels. The grain size of LDX2101 was substantially greater than that of DSS2205, and the microhardness difference of LDX2101 was larger than that of DSS2205. This difference hinders the transfer of strain from ferrite to austenite. In the rolling process, the ferrite grains of LDX2101 underwent continuous softening and were substantially refined. However, although little recrystallization occurred at the boundaries of austenite, serious deformation accumulated in the interior of austenite, leading to a substantial increase in hardness. The main cause of crack formation is the microhardness difference between ferrite and austenite.
基金Item Sponsored by National Natural Science Foundation of China (50504007 ,50474086 ,50334010)
文摘The recrystallization kinetics and grain size models were developed for the C Mn and niobium containing steels to describe the metallurgical phenomenon such as softening, grain growth, and strain accumulation. Based on the recrystallization kinetics equations, the mean flow stress and the rolling load of each pass were predicted and the optimum rolling schedule was proposed for hot strip rolling. The austenite grain refinement is associated with the addition of niobium, the decrease of starting temperature of finish rolling, and the reduction of finished thickness. The mean flow stress curve with a continuous rising characteristic can be usually observed in the finish rolling of niobium containing steel, which is formed as a result of the heavy incomplete softening and strain accumulation. The predic ted rolling loads are in good agreement with the measured ones.
基金This study was financially supported by the National Natural Science Foundation of China (No.50504007, No.50474086, and No.50334010).
文摘An integrated metallurgical model was developed for Nb steels to predict the microstructure evolution and mechanical properties during the hot-strip rolling and cooling process. On the basis of the industrial data, the transformation kinetics, strength, and elongation rate were evaluated for different chemical compositions and processing parameters. The yield strength and tensile strength increase with increasing Nb content or decreasing finishing temperature. The bainite distributed in finer ferrite matrix, which is produced at relatively low coiling temperatures, can greatly increase the strength of steel, especially tensile strength, thereby decreasing the yield ratio. A reasonable agreement was found between the predicted and measured results. It indicates that the present models can be used to simulate the actual production process.
文摘Microstructures and properties of three Nb micro-alloyed steels were studied through hot rolling experiment. The result indicates that the ferrite grain size （dF ） decreases with increasing Nb content （Nb）, and the bainite fraction （fB） increases with increasing Nb content （Nb）. The effect of ferrite grain size （dF） on yield strength （δy） is related to Nb content （Nb）, and the effect of bainite fraction （fB） on yield strength （δy） is unrelated to Nb content （Nb）. Modelling of yield strength （δy） for Nb micro-alloyed steels with high accuracy has been built up with Nb content （Nb） and bainite fraction （fB） taken into account as new parameters, and formulas for ferrite grain size （dF ） and bainite fraction （fB） vs Nb content （Nb） have also been established under the experiment conditions. The research results could provide instructions for industrial productions.
文摘Average grain size and grain size distribution in as hot-rolled SPHC, SPHD, and SPHE sheets manufac- tured by compact strip production （CSP） processing and traditional continuous casting and rolling （CCR） processing respectively were investigated by quantitative metallographic method. The results show that the average grain size and distribution width of grain size in sheets manufactured by CSP processing was obviously larger than that by CCR processing. It was analyzed that multi-phase transformation and high reduction ratio in CCR processing resulted in refining grain size, which would be dominant reason for controlling grain size. In plain carbon steels such as SPHC, SPHD and SPHE, the effect of fine precipitation in CSP on behavior of deformation and recrystallization of austenite during roiling, and consequent refinement of grain size seem not to be as important as the effect of reheating and roughing in CCR processing. Homogenizing in reheating and refining grain size in roughing in CCR processing would refine final grain size and also make grain size homogenized, Very coarse grain size would result in mixed grain size, large distribution width of grain size due to interaction of static and dynamic recrystallization in CSP processing
基金financially supported by the National Basic Research Program of China(No.2010CB630805)the National Natural Science Foundation of China(No.51201036)China Iron&Steel Research Institute Group(No.12060840A)
文摘A new Ti-V-Mo complex microalloyed hot-rolled high-strength steel sheet was developed by controlling a thermo-mechanical controlled processing （TMCP） schedule, in particular with variants in coiling temperature. The effects of coiling temperature （CT） on various hardening mechanisms and mechanical properties of Ti-V-Mo complex mi- croalloyed high-strength low-alloy steels were investigated. The results revealed that the steels are mainly strengthened by a combined effect of ferrite grain refinement hardening and precipitation hardening. The variation in simulated coiling temperature causes a significant difference in strength, which is mainly attributed to different precipitation hardening increment contributions. When the CT is 600 ℃, the experimental steel has the best mechanical properties： ultimate tensile strength （UTS） 1000 MPa, yield strength （YS） 955 MPa and elongation （EL） 17%. Moreover, about 82 wt% of the total precipitates are nano-sized carbide particles with diameter of 1-10 nm, which is randomly dispersed in the ferrite matrix. The nano-sized carbide particles led to a strong precipitation hardening increment up to 310 MPa.
