Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical prope...Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical properties and precipitated phase of the weld joints. The results showed that during the annealing treatment（200 ℃-1 h, 250 ℃-1 h, 300 ℃-1 h, 350 ℃-1 h, 400 ℃-1 h, and 450 ℃-1 h）, the average grain size in the weld seam was the minimum after annealing at 400 ℃ for 1 hour, and then abnormally grew up after annealing at 450 ℃ for 1 hour. The mechanical properties enhanced when the joints were processed from 200 ℃-1 h to 400 ℃-1 h but sharply decreased with increasing annealing temperature. In contrast to the annealing treatment, solution treatment（250 ℃-10 h, 300 ℃-10 h, 350 ℃-10 h, 400 ℃-10 h, and 450 ℃-10 h） exhibited a better ductility but a slight deterioration in tensile strength. Especially speaking, no eutectic compounds（such as Mg17 Al12） were observed in the weld seam. The supersaturated Al atoms were precipitated in a coarse spherical shape dispersed in the weld seam. The precipitated Al atoms dissolved in the matrix substances at the condition（400 ℃-1 h） or（250 ℃-10 h）. The solution treatment caused grain coarsening and precipitated Al atoms dissolved in the weld seam substantially, which resulted in a drop in micro-hardness at the weld seam compared to the area of the annealed joints.展开更多
An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone（HAZ）.The fracture parameters Jand C＊are e...An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone（HAZ）.The fracture parameters Jand C＊are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS.A middle crack tension（M（T））specimen is utilized in the analysis for different material properties and geometries of the weldment.The influence of mechanical property and geometry on the fracture parameters Jand C＊of the specimen is discussed for the welded joints with HAZ crack.The results suggest that the HAZ property is a significant factor in the estimation of Jand C＊for the mismatched welded joint with HAZ crack.展开更多
The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural ...The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural gas exploration in the study area.This paper analyzes the hydrocarbon potential of each sag in this basin from the perspective of control of both source rocks and geothermal heat.Two types of source rocks occur in the Yacheng Fm,namely mudstone of transitional facies and mudstone of neritic facies.Both of them are dominated by a kerogen of type-III,followed by type-II.Their organic matter abundances are controlled by the amount of continental clastic input.The mudstone of transitional facies is commonly higher in organic matter abundance,while that of neritic facies is lower.The coal-measure source rocks of transitional facies were mainly formed in such environments as delta plains,coastal plains and barrier tidal flat-marshes.Due to the control of Cenozoic lithosphere extension and influence of neotectonism,the geothermal gradient,terrestrial heat flow value(HFV)and level of thermal evolution are generally high in deep water.The hot setting not only determines the predominance of gas generation in the deep-water sags,but can promote the shallow-buried source rocks in shallow water into oil window to generate oil.In addition to promoting the hydrocarbon generation of source rocks,the high geothermal and high heat flow value can also speed up the cracking of residual hydrocarbons,thus enhancing hydrocarbon generation efficiency and capacity.According to the theory of joint control of source quality and geothermal heat on hydrocarbon generation,we comprehensively evaluate and rank the exploration potentials of major sags in the Qiongdongnan Basin.These sags are divided into 3 types,of which type-I sags including Yanan,Lingshui,Baodao,Ledong and Huaguang are the highest in hydrocarbon exploration potential.展开更多
To solve the problem about the inhomogeneous thermal effect of pot heated by coils along the circumference, a novel coil winding method is proposed and compared with the general winding method in the paper. First, bas...To solve the problem about the inhomogeneous thermal effect of pot heated by coils along the circumference, a novel coil winding method is proposed and compared with the general winding method in the paper. First, based on the Biot-Savart law and Ampere＇s rule, the magnetic induction generated by a straight current carrying conductor and a current loop is discussed, respectively. Then the novel coil winding method is developed by adjusting the location of inhomogeneous joints. The joints are periodically scattered along the circumferential direction and symmetrically designed around the central axis.Numerical results show that the quite non-uniform temperature in the base of pot at the circular direction is effectively improved by using the proposed winding method. The potential danger produced by high temperature at some region of coils plate is minimized.It is energy-efficient and safe for residential appliances.展开更多
基金Funded by the National Natural Science Foundation of China(Nos.51505322,51175364)Natural Science Foundation of Shanxi Province of China(No.2013011014-3)
文摘Tungsten inert gas（TIG） welding was performed on 2.7 mm thick commercial extruded AZ31 B magnesium alloy plates. We investigated the effect of post-weld heat treatment（PWHT） on the microstructure, mechanical properties and precipitated phase of the weld joints. The results showed that during the annealing treatment（200 ℃-1 h, 250 ℃-1 h, 300 ℃-1 h, 350 ℃-1 h, 400 ℃-1 h, and 450 ℃-1 h）, the average grain size in the weld seam was the minimum after annealing at 400 ℃ for 1 hour, and then abnormally grew up after annealing at 450 ℃ for 1 hour. The mechanical properties enhanced when the joints were processed from 200 ℃-1 h to 400 ℃-1 h but sharply decreased with increasing annealing temperature. In contrast to the annealing treatment, solution treatment（250 ℃-10 h, 300 ℃-10 h, 350 ℃-10 h, 400 ℃-10 h, and 450 ℃-10 h） exhibited a better ductility but a slight deterioration in tensile strength. Especially speaking, no eutectic compounds（such as Mg17 Al12） were observed in the weld seam. The supersaturated Al atoms were precipitated in a coarse spherical shape dispersed in the weld seam. The precipitated Al atoms dissolved in the matrix substances at the condition（400 ℃-1 h） or（250 ℃-10 h）. The solution treatment caused grain coarsening and precipitated Al atoms dissolved in the weld seam substantially, which resulted in a drop in micro-hardness at the weld seam compared to the area of the annealed joints.
基金Sponsored by National High Technology Research and Development Program of China(2012AA040106)
文摘An idealized tri-material assumption is established to describe the constitutive relationship of mismatched welded joints by considering the influence of heat affected zone（HAZ）.The fracture parameters Jand C＊are estimated for mismatched welded joints with HAZ cracks by finite element analysis with ABAQUS.A middle crack tension（M（T））specimen is utilized in the analysis for different material properties and geometries of the weldment.The influence of mechanical property and geometry on the fracture parameters Jand C＊of the specimen is discussed for the welded joints with HAZ crack.The results suggest that the HAZ property is a significant factor in the estimation of Jand C＊for the mismatched welded joint with HAZ crack.
基金National Key Basic Research and Development Plan(973 plans)“Basic research on oil and gas formation and distribution in deep water basins in South China Sea”(No.2009CB219400)Special and Significant Project of National Science and Technology“Key technology of marine oil and gas exploration in deep water area”(No.2008ZX05025 and 2011ZX05025)Investigation and Evaluation Project of National Strategic Petroleum Resource Provinces of the Ministry of Land and Resources(No.XQ-2004-05 and XQ-2007-05).
文摘The Oligocene Yacheng Fm contains the most important source rocks that have been confirmed by exploratory wells in the Qiongdongnan Basin.The efficiency of these source rocks is the key to the breakthrough in natural gas exploration in the study area.This paper analyzes the hydrocarbon potential of each sag in this basin from the perspective of control of both source rocks and geothermal heat.Two types of source rocks occur in the Yacheng Fm,namely mudstone of transitional facies and mudstone of neritic facies.Both of them are dominated by a kerogen of type-III,followed by type-II.Their organic matter abundances are controlled by the amount of continental clastic input.The mudstone of transitional facies is commonly higher in organic matter abundance,while that of neritic facies is lower.The coal-measure source rocks of transitional facies were mainly formed in such environments as delta plains,coastal plains and barrier tidal flat-marshes.Due to the control of Cenozoic lithosphere extension and influence of neotectonism,the geothermal gradient,terrestrial heat flow value(HFV)and level of thermal evolution are generally high in deep water.The hot setting not only determines the predominance of gas generation in the deep-water sags,but can promote the shallow-buried source rocks in shallow water into oil window to generate oil.In addition to promoting the hydrocarbon generation of source rocks,the high geothermal and high heat flow value can also speed up the cracking of residual hydrocarbons,thus enhancing hydrocarbon generation efficiency and capacity.According to the theory of joint control of source quality and geothermal heat on hydrocarbon generation,we comprehensively evaluate and rank the exploration potentials of major sags in the Qiongdongnan Basin.These sags are divided into 3 types,of which type-I sags including Yanan,Lingshui,Baodao,Ledong and Huaguang are the highest in hydrocarbon exploration potential.
基金supported by the National Natural Science Foundation of China under Grant No.41304119,No.41104097,and No.61201007the Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20120185120012the Oversea Academic Training Fund sponsored by China Scholarship Council and University of Electronic Science and Technology of China under Grant No.201306075027
文摘To solve the problem about the inhomogeneous thermal effect of pot heated by coils along the circumference, a novel coil winding method is proposed and compared with the general winding method in the paper. First, based on the Biot-Savart law and Ampere＇s rule, the magnetic induction generated by a straight current carrying conductor and a current loop is discussed, respectively. Then the novel coil winding method is developed by adjusting the location of inhomogeneous joints. The joints are periodically scattered along the circumferential direction and symmetrically designed around the central axis.Numerical results show that the quite non-uniform temperature in the base of pot at the circular direction is effectively improved by using the proposed winding method. The potential danger produced by high temperature at some region of coils plate is minimized.It is energy-efficient and safe for residential appliances.
