Strain capacity is an important performance indicator for designing and evaluating high-grade steel pipelines.Due to the inhomogeneity of material properties in welded structures,girth welds are one of the main factor...Strain capacity is an important performance indicator for designing and evaluating high-grade steel pipelines.Due to the inhomogeneity of material properties in welded structures,girth welds are one of the main factors that restrict the strain capacity of pipelines.In this paper,girth-welded pipes with cracks in the inner surface of the weld have been studied,and the ductile crack initiation and propagation behavior have been simulated using the Gurson model.The corresponding nominal strain at the onset of crack initiation was defined as the characteristic value of strain capacity.The influencing factors on the strain concentration area,strain concentration factor,and strain capacity of girth-welded pipes were quantitatively analyzed.A semiempirical calculation formula for the strain capacity of typical girthwelded X80 grade pipes has been proposed as a function of the crack size,mismatch coefficient of the weld,and softening degree of the heat affected zone(HAZ).This study can facilitate the defect assessment of girth-welded pipes.展开更多
Nowadays,many research works are carried for all grades of concrete to make the concrete most economical and durable there by adding the supplementary cementitious materials and alternative replacement aggregates.In t...Nowadays,many research works are carried for all grades of concrete to make the concrete most economical and durable there by adding the supplementary cementitious materials and alternative replacement aggregates.In this research work deals with the experimental investigation of mechanical properties of the M30,M50 and M80 grade concrete by replacing the fine and coarse aggregate by foundry sand and crushed concrete waste respectively.Mix design procedures were followed as per IRC44:2017 guidelines and recommendation.Proper dosage of super plasticizer(SP)was maintained in the concrete to make it better performed.In this present investigation,a Poly Propylene fibre(PPF)of 0.3%by weight of the cement is used.Mechanical properties such as Compressive strength and Flexural Strength were determined by preparing the respective mould sizes for specific test and are cured for 7,14 and 28 days and result obtained for respective days were tabulated and discussed.展开更多
三嗪染料(Cibacron blue F3G-A)的蒽醌部分结构类似于腺嘌呤,可以用于亲和分离以NAD+(NADP+)和FAD为辅酶的脱氢酶。三嗪染料通过亲核取代反应修饰曲通X-100,形成的三嗪染料-曲通X-100与成相聚合物吐温80、磷酸钾盐构成液-固亲和萃取体...三嗪染料(Cibacron blue F3G-A)的蒽醌部分结构类似于腺嘌呤,可以用于亲和分离以NAD+(NADP+)和FAD为辅酶的脱氢酶。三嗪染料通过亲核取代反应修饰曲通X-100,形成的三嗪染料-曲通X-100与成相聚合物吐温80、磷酸钾盐构成液-固亲和萃取体系。从猪心肌匀浆液纯化苹果酸脱氢酶的条件:三嗪染料-曲通X-100浓度为1.2%(W/V),吐温80浓度9%(V/V),猪心肌匀浆液0.25 mL(2.5%),pH 8.0,加入成相磷酸钾终浓度1.6 mol/L,形成液固两相,固相酶活力平均收得率为81.01%,纯化倍数为4.93。固相30℃保温溶解,加入成相盐磷酸钾,终浓度为0.7 mol/L,二次成相。低盐浓度条件下,近80%的酶反萃回液相,简化了苹果酸脱氢酶后续加工工艺。展开更多
The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal ...The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal simulator. The results showed that the high-Nb steels have excellent weldability. Ernbrittlement regions appear in coarse grain heat affected zone （CGHAZ） and intercritically heat affected zone （ICHAZ） ~ Softening region appears in fine-grain heat affected zone （FGHAZ）, and the strength here was even lower than 555 MPa as required in the standard. Meanwhile, with the increase of heat input, the strength and the toughness of HAZ of steel with high Nb, C and lower alloy decrease notably. Therefore, take into account the welding procedure during manufacture of weld pipe, suitable amount of alloy elements, such as Cr, Ni, Cu, Mo and so on, is necessary for high Nb X80 heavy- thick steel plate.展开更多
The relationship between microstructures and mechanical properties of a medium carbon V-N microalloyed steel used for N80 seamless oil-well tubes of hot rolling non-quenched/tempered (non-Q and T) was investigated.The...The relationship between microstructures and mechanical properties of a medium carbon V-N microalloyed steel used for N80 seamless oil-well tubes of hot rolling non-quenched/tempered (non-Q and T) was investigated.The results have shown that volume percentages of upper bainite,modified bainite and ferrite have a decisive influence on impact energies of steel tubes.When the total volume percentage of bainite is larger than 5%,the impact energy of tubes can not satisfy with the industrial criteria.Moreover,if the total volume percentage of bainite is smaller than 5%,then the impact energy of steel tubes enhances with volume percentage of ferrite increasing.The final microstructures have closely relation with tube billet quality,controlled cooling temperature after tube rolling and cooling method after stretch-reduction-diameter.High quality of medium carbon V-N microalloyed steel for non-Q and T oil-well tubes can be produced through comprehensive control of microstructures and mechanical properties in sub-procedures,especially for tube billet quality and controlled cooling parameters.展开更多
基金supported by the grants from the National Natural Science Foundation of China(Grant No.51874324)the Chinese Scholarship Council(CSC)for the financial support。
文摘Strain capacity is an important performance indicator for designing and evaluating high-grade steel pipelines.Due to the inhomogeneity of material properties in welded structures,girth welds are one of the main factors that restrict the strain capacity of pipelines.In this paper,girth-welded pipes with cracks in the inner surface of the weld have been studied,and the ductile crack initiation and propagation behavior have been simulated using the Gurson model.The corresponding nominal strain at the onset of crack initiation was defined as the characteristic value of strain capacity.The influencing factors on the strain concentration area,strain concentration factor,and strain capacity of girth-welded pipes were quantitatively analyzed.A semiempirical calculation formula for the strain capacity of typical girthwelded X80 grade pipes has been proposed as a function of the crack size,mismatch coefficient of the weld,and softening degree of the heat affected zone(HAZ).This study can facilitate the defect assessment of girth-welded pipes.
文摘Nowadays,many research works are carried for all grades of concrete to make the concrete most economical and durable there by adding the supplementary cementitious materials and alternative replacement aggregates.In this research work deals with the experimental investigation of mechanical properties of the M30,M50 and M80 grade concrete by replacing the fine and coarse aggregate by foundry sand and crushed concrete waste respectively.Mix design procedures were followed as per IRC44:2017 guidelines and recommendation.Proper dosage of super plasticizer(SP)was maintained in the concrete to make it better performed.In this present investigation,a Poly Propylene fibre(PPF)of 0.3%by weight of the cement is used.Mechanical properties such as Compressive strength and Flexural Strength were determined by preparing the respective mould sizes for specific test and are cured for 7,14 and 28 days and result obtained for respective days were tabulated and discussed.
基金Item Sponsored by National Natural Science Foundation of China(51171162)Natural Science Foundation of Hebei Province of China(E2011203169)The R&D Project of CITIC-CBMM(2011-D056-3)
文摘The mechanical properties of heat affected zone （HAZ） of two commercial high-Nb X80 grade pipeline steels with different alloy elements were investigated using thermal simulation performed on a Gleeble-3500 thermal simulator. The results showed that the high-Nb steels have excellent weldability. Ernbrittlement regions appear in coarse grain heat affected zone （CGHAZ） and intercritically heat affected zone （ICHAZ） ~ Softening region appears in fine-grain heat affected zone （FGHAZ）, and the strength here was even lower than 555 MPa as required in the standard. Meanwhile, with the increase of heat input, the strength and the toughness of HAZ of steel with high Nb, C and lower alloy decrease notably. Therefore, take into account the welding procedure during manufacture of weld pipe, suitable amount of alloy elements, such as Cr, Ni, Cu, Mo and so on, is necessary for high Nb X80 heavy- thick steel plate.
基金financial support from Chinese National Nature Science Fund(Project No.50271009and No.51071019)Wuxi Seamless Steel Tube Company,Ltdthe Vanadium International Technical Committee via the CSM
文摘The relationship between microstructures and mechanical properties of a medium carbon V-N microalloyed steel used for N80 seamless oil-well tubes of hot rolling non-quenched/tempered (non-Q and T) was investigated.The results have shown that volume percentages of upper bainite,modified bainite and ferrite have a decisive influence on impact energies of steel tubes.When the total volume percentage of bainite is larger than 5%,the impact energy of tubes can not satisfy with the industrial criteria.Moreover,if the total volume percentage of bainite is smaller than 5%,then the impact energy of steel tubes enhances with volume percentage of ferrite increasing.The final microstructures have closely relation with tube billet quality,controlled cooling temperature after tube rolling and cooling method after stretch-reduction-diameter.High quality of medium carbon V-N microalloyed steel for non-Q and T oil-well tubes can be produced through comprehensive control of microstructures and mechanical properties in sub-procedures,especially for tube billet quality and controlled cooling parameters.
