The wedge and bulge expansion tests were compared in the assessment of the seam welds strength in a tubular profile extruded at two ram speeds.In the wedge test,the expansion was determined by moving a conical punch i...The wedge and bulge expansion tests were compared in the assessment of the seam welds strength in a tubular profile extruded at two ram speeds.In the wedge test,the expansion was determined by moving a conical punch into the tube until the specimen fracture.In the bulge test,a hydrostatic tensile stress state was applied by expanding the specimen with an internal rubber plug.The two methodologies were compared in terms of load and hoop strain at fracture and by detecting the fracture morphology and location.Then,the effect of a number of design parameters was investigated in order to evaluate the robustness of the standard testing conditions.For both tests,ductile fractures appeared in the seam welds location,but the bulge test was more robust and conservative with respect to the wedge test,showing less scattered data.Thus,the performances of a second die for the tube profile,designed to optimize the seam welds quality,have been successfully assessed by the bulge test and results compared to those achieved by a novel numerical quality index,coming to a final good matching.展开更多
Equal channel angular expansion extrusion with spherical cavity(ECAEE-SC)was introduced as a novel severe plastic deformation(SPD)technique,which is capable of imposing large plastic strain and intrinsic back-pressure...Equal channel angular expansion extrusion with spherical cavity(ECAEE-SC)was introduced as a novel severe plastic deformation(SPD)technique,which is capable of imposing large plastic strain and intrinsic back-pressure on the processed billet.The plastic deformation behaviors of commercially pure aluminum during ECAEE-SC process were investigated using finite element analysis DEFORM-3D simulation software.The material flow,the load history,the distribution of effective strain and mean stress in the billet were analyzed in comparison with conventional equal channel angular extrusion(ECAE)process.In addition,single-pass ECAEE-SC was experimentally conducted on commercially pure aluminum at room temperature for validation,and the evolution of microstructure and microhardness of as-processed material was discussed.It was shown that during the process,the material is in the ideal hydrostatic stress state and the load requirement for ECAEE-SC is much more than that for ECAE.After a single-pass ECAEE-SC,an average strain of 3.51 was accumulated in the billet with homogeneous distribution.Moreover,the microstructure was significantly refined and composed of equiaxed ultrafine grains with sub-micron size.Considerable improvement in the average microhardness of aluminum was also found,which was homogenized and increased from HV 36.61 to HV 70.20,denoting 91.75%improvement compared with that of the as-cast billet.展开更多
文摘The wedge and bulge expansion tests were compared in the assessment of the seam welds strength in a tubular profile extruded at two ram speeds.In the wedge test,the expansion was determined by moving a conical punch into the tube until the specimen fracture.In the bulge test,a hydrostatic tensile stress state was applied by expanding the specimen with an internal rubber plug.The two methodologies were compared in terms of load and hoop strain at fracture and by detecting the fracture morphology and location.Then,the effect of a number of design parameters was investigated in order to evaluate the robustness of the standard testing conditions.For both tests,ductile fractures appeared in the seam welds location,but the bulge test was more robust and conservative with respect to the wedge test,showing less scattered data.Thus,the performances of a second die for the tube profile,designed to optimize the seam welds quality,have been successfully assessed by the bulge test and results compared to those achieved by a novel numerical quality index,coming to a final good matching.
基金Project(51905462)supported by the National Natural Science Foundation of ChinaProject(BK20200297)supported by the Natural Science Foundation of Jiangsu Province,China+1 种基金Project(GDZB-127)supported by Jiangsu Provincial“Six Talent Peaks”Program,ChinaProject(2018202)supported by the“Youth Science and Technology Talents'Sponsored Program of Jiangsu Science and Technology Association,China。
文摘Equal channel angular expansion extrusion with spherical cavity(ECAEE-SC)was introduced as a novel severe plastic deformation(SPD)technique,which is capable of imposing large plastic strain and intrinsic back-pressure on the processed billet.The plastic deformation behaviors of commercially pure aluminum during ECAEE-SC process were investigated using finite element analysis DEFORM-3D simulation software.The material flow,the load history,the distribution of effective strain and mean stress in the billet were analyzed in comparison with conventional equal channel angular extrusion(ECAE)process.In addition,single-pass ECAEE-SC was experimentally conducted on commercially pure aluminum at room temperature for validation,and the evolution of microstructure and microhardness of as-processed material was discussed.It was shown that during the process,the material is in the ideal hydrostatic stress state and the load requirement for ECAEE-SC is much more than that for ECAE.After a single-pass ECAEE-SC,an average strain of 3.51 was accumulated in the billet with homogeneous distribution.Moreover,the microstructure was significantly refined and composed of equiaxed ultrafine grains with sub-micron size.Considerable improvement in the average microhardness of aluminum was also found,which was homogenized and increased from HV 36.61 to HV 70.20,denoting 91.75%improvement compared with that of the as-cast billet.
