The 30 mm thick ASTM4130 steel pipe was fabricated by gas tungsten arc welding and shielded metal arc welding under quenched and tempered conditions. Whereafier, the mechanical properties of welded joints of both V gr...The 30 mm thick ASTM4130 steel pipe was fabricated by gas tungsten arc welding and shielded metal arc welding under quenched and tempered conditions. Whereafier, the mechanical properties of welded joints of both V groove and combination double V groove were measured, while the microstructure feature and fracture morphology of both welded joints were investigated. Moreover, the effect of groove shapes on the properties of welded joints was explored. The results show that the welding efficiency of the combination double V groove joint is as two times as that of the V groove joint. But the hardness and toughness of the heat-affected zone （HAZ） with combination double V groove can not satisfy the requirements. Also, the coarse grain heat-affected zone （CGHAZ） of the cap layer is mainly composed of granular bainite, tempered martensite and a small amount of carbon-free bainite, and the fractured swface of the fusion line is entirely dominated by the quasi-cleavage mode. That the mechanical properties of the combination double V groove are lower than that of the V groove lie in the penetration ratio, welding heat input, and the areas and distribution feature of brittle zones. The combination double V groove is not suitable for the fabricating of ASTM4130 steel.展开更多
Thin-walled member is structurally superior to a construction member. However, by reason of complexity in structure the stress and the deformation to yield the cross section are complicated. Specially, in case thin-wa...Thin-walled member is structurally superior to a construction member. However, by reason of complexity in structure the stress and the deformation to yield the cross section are complicated. Specially, in case thin-walled members, such as thin-walled channel section columns, which are subjected to compressive force, these members produce the local buckling, distortional buckling and overall buckling. A number of experimental and theoretical investigations subjected to axial compressive force are generated for thin-walled channel section columns with triangle-shaped folded groove by Hancock [1] and with complex edge stiffeners and web stiffeners by Wang [2]. In case thin-walled channel section column with folded groove which is subjected to axial compressive force, it is cleared that the buckling mode shapes are ordinarily generated for local buckling mode shape of plate-panel composing cross section of member in short member aspect ratio and overall buckling mode shape as column and distortional buckling mode shape interacting between local buckling and overall buckling similarly normal thin-walled member. It is cleared analytically and experimentally that buckling strength and critical strength of thin-walled channel section column with folded groove can increase sharply in comparison with that of normal thin-walled member composing only plate-panel. In this paper a new cross section of shell-shaped curved groove [3] was proposed instead of the thin-walled lipped channel section column with triangle- and rectangle-shaped folded grooves used ordinarily, and therefore the comparison and the examination of buckling strength and buckling behavior were generated in the case of preparing triangle-shaped folded and shell-shaped curved grooves to web and flange of thin-walled channel section column. And then in order to investigate the buckling behavior on the thin-walled channel section column with folded and curved grooves, exact buckling strength and the buckling mode shapes are generated by using the transfer matrix method. The analytical local distortional and overall elastic buckling loads of thin-walled channel section column with folded and curved grooves can be obtained simultaneously by use of the transfer matrix method. Furthermore, a technique to estimate the buckling mode shapes of these members is also shown.展开更多
The groove shape of the weld faying part was investigated to obtain an ideal pipe frictiowelded joint that had a fracture in the base metal and no inner flash of it.The steel pipe had inner and outer diameters of 8.0 ...The groove shape of the weld faying part was investigated to obtain an ideal pipe frictiowelded joint that had a fracture in the base metal and no inner flash of it.The steel pipe had inner and outer diameters of 8.0 mm and 13.5 mm,respectively,and the weld faying surface was of a basic flat shape(butt)type.Moreover,stepped and tapered groove shapes were prepared.Pipe groove shapes were welded with a friction speed of 27.5 s_1 and a friction load of 2.79 kN.Joining phenomena during the welding process were observed,and the tensile strength of joints was evaluated.The joints,that fabricated with flat or step groove shapes,made with a friction time at which the friction torque reached the initial peak did not have the tensile strength of the base metal nor a fracture in the base metal.However,the joints fabricated with a friction time that reached past the initial peak had a large flash,and they contained a fracture in the base metal.In contrast,when joints were made with a gently tapered groove shape with a friction time reaching the time of the initial peak,they achieved a fracture in the base metal,despite having an extremely small inner flash.Therefore,the shape at the weld faying part was capable of reducing the flash exhausted from the weld interface.展开更多
基金supported and funded in part by a grant(Project No.ZR2013EEQ027)from the Natural Science Foundation of Shandong Provincea grant(Project No.14CX02066A)from the Fundamental Research Funds for the Central Universities of China
文摘The 30 mm thick ASTM4130 steel pipe was fabricated by gas tungsten arc welding and shielded metal arc welding under quenched and tempered conditions. Whereafier, the mechanical properties of welded joints of both V groove and combination double V groove were measured, while the microstructure feature and fracture morphology of both welded joints were investigated. Moreover, the effect of groove shapes on the properties of welded joints was explored. The results show that the welding efficiency of the combination double V groove joint is as two times as that of the V groove joint. But the hardness and toughness of the heat-affected zone （HAZ） with combination double V groove can not satisfy the requirements. Also, the coarse grain heat-affected zone （CGHAZ） of the cap layer is mainly composed of granular bainite, tempered martensite and a small amount of carbon-free bainite, and the fractured swface of the fusion line is entirely dominated by the quasi-cleavage mode. That the mechanical properties of the combination double V groove are lower than that of the V groove lie in the penetration ratio, welding heat input, and the areas and distribution feature of brittle zones. The combination double V groove is not suitable for the fabricating of ASTM4130 steel.
基金Projects （50436010, 50375055, 50175028） supported by the National Natural Science Foundation of China Project （04105942） supported by the Natural Science Foundation of Guangdong Province, China
文摘Thin-walled member is structurally superior to a construction member. However, by reason of complexity in structure the stress and the deformation to yield the cross section are complicated. Specially, in case thin-walled members, such as thin-walled channel section columns, which are subjected to compressive force, these members produce the local buckling, distortional buckling and overall buckling. A number of experimental and theoretical investigations subjected to axial compressive force are generated for thin-walled channel section columns with triangle-shaped folded groove by Hancock [1] and with complex edge stiffeners and web stiffeners by Wang [2]. In case thin-walled channel section column with folded groove which is subjected to axial compressive force, it is cleared that the buckling mode shapes are ordinarily generated for local buckling mode shape of plate-panel composing cross section of member in short member aspect ratio and overall buckling mode shape as column and distortional buckling mode shape interacting between local buckling and overall buckling similarly normal thin-walled member. It is cleared analytically and experimentally that buckling strength and critical strength of thin-walled channel section column with folded groove can increase sharply in comparison with that of normal thin-walled member composing only plate-panel. In this paper a new cross section of shell-shaped curved groove [3] was proposed instead of the thin-walled lipped channel section column with triangle- and rectangle-shaped folded grooves used ordinarily, and therefore the comparison and the examination of buckling strength and buckling behavior were generated in the case of preparing triangle-shaped folded and shell-shaped curved grooves to web and flange of thin-walled channel section column. And then in order to investigate the buckling behavior on the thin-walled channel section column with folded and curved grooves, exact buckling strength and the buckling mode shapes are generated by using the transfer matrix method. The analytical local distortional and overall elastic buckling loads of thin-walled channel section column with folded and curved grooves can be obtained simultaneously by use of the transfer matrix method. Furthermore, a technique to estimate the buckling mode shapes of these members is also shown.
文摘The groove shape of the weld faying part was investigated to obtain an ideal pipe frictiowelded joint that had a fracture in the base metal and no inner flash of it.The steel pipe had inner and outer diameters of 8.0 mm and 13.5 mm,respectively,and the weld faying surface was of a basic flat shape(butt)type.Moreover,stepped and tapered groove shapes were prepared.Pipe groove shapes were welded with a friction speed of 27.5 s_1 and a friction load of 2.79 kN.Joining phenomena during the welding process were observed,and the tensile strength of joints was evaluated.The joints,that fabricated with flat or step groove shapes,made with a friction time at which the friction torque reached the initial peak did not have the tensile strength of the base metal nor a fracture in the base metal.However,the joints fabricated with a friction time that reached past the initial peak had a large flash,and they contained a fracture in the base metal.In contrast,when joints were made with a gently tapered groove shape with a friction time reaching the time of the initial peak,they achieved a fracture in the base metal,despite having an extremely small inner flash.Therefore,the shape at the weld faying part was capable of reducing the flash exhausted from the weld interface.
