The Experts below are selected from a list of 48 Experts worldwide ranked by ideXlab platform
Tomokatsu Aizawa - One of the best experts on this subject based on the ideXlab platform.
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interfacial microstructure and strength of steel aluminum alloy lap joint fabricated by magnetic pressure seam welding
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Shinji Kumai, Takashi Arai, Tomokatsu AizawaAbstract:Lap joining of low carbon steel (SPCC)/A6111 aluminum alloy was carried out using the magnetic pressure seam welding method. Interfacial microstructure, in particular, an intermediate layer formed at the weld interface was precisely examined using TEM. Tensile tests were also performed for the lap joints. Lap joining was successfully attained in several microseconds with no temperature increase. Weld interface of the lap joint showed wavy morphology and the intermediate layer was observed along the wavy interface. These microstructures are similar to that of the explosive weld lap joint. TEM observation revealed that the intermediate layers consist of fine aluminum grains (around 100 nm) and more finely dispersed intermetallic particles. A6111 matrix close to the weld interface also exhibited extremely refined grain structure. The bonding strength of the joint was quite high and it failed at the Parent Plate. The multi-phase intermediate layer and grain-refined aluminum layer are considered to be the origin of high interfacial bonding strength of the lap joint.
Robert J Sebring - One of the best experts on this subject based on the ideXlab platform.
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residual stress measurements in a thick dissimilar aluminum alloy friction stir weld
Acta Materialia, 2006Co-Authors: Michael B Prime, Thomas Gnaupelherold, John A Baumann, Richard J Lederich, David M Bowden, Robert J SebringAbstract:Abstract Plates (25.4 mm thick) of aluminum alloys 7050-T7451 and 2024-T351 were joined in a butt joint by friction stir welding (FSW). A 54 mm long test specimen was removed from the Parent Plate, and cross-sectional maps of residual stresses were measured using neutron diffraction and the contour method. The stresses in the test specimen peaked at only about 32 MPa and had the conventional “M” profile with tensile stress peaks in the heat-affected zone outside the weld. The asymmetric stress distribution is discussed relative to the FSW process and the regions of highest thermal gradients. The general agreement between the two measurement techniques validated the ability of each technique to measure the low-magnitude stresses, less than 0.05% of the elastic modulus. Subtle differences between the two were attributed to spatial variations in the unstressed lattice spacing (d0) and also intergranular strains affecting the neutron results. The FSW stresses prior to relaxation from removal of the test specimen were estimated to have been about 43 MPa, demonstrating the ability of FSW to produce low-stress welds in even fairly thick sections. To avoid the estimated 25% stress relaxation from removing the test specimen, the specimen would have had to be quite long because the St. Venant’s characteristic distance in this case was more related to the transverse dimensions of the specimen than to the Plate thickness.
Shinji Kumai - One of the best experts on this subject based on the ideXlab platform.
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interfacial microstructure and strength of steel aluminum alloy lap joint fabricated by magnetic pressure seam welding
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Shinji Kumai, Takashi Arai, Tomokatsu AizawaAbstract:Lap joining of low carbon steel (SPCC)/A6111 aluminum alloy was carried out using the magnetic pressure seam welding method. Interfacial microstructure, in particular, an intermediate layer formed at the weld interface was precisely examined using TEM. Tensile tests were also performed for the lap joints. Lap joining was successfully attained in several microseconds with no temperature increase. Weld interface of the lap joint showed wavy morphology and the intermediate layer was observed along the wavy interface. These microstructures are similar to that of the explosive weld lap joint. TEM observation revealed that the intermediate layers consist of fine aluminum grains (around 100 nm) and more finely dispersed intermetallic particles. A6111 matrix close to the weld interface also exhibited extremely refined grain structure. The bonding strength of the joint was quite high and it failed at the Parent Plate. The multi-phase intermediate layer and grain-refined aluminum layer are considered to be the origin of high interfacial bonding strength of the lap joint.
Michael B Prime - One of the best experts on this subject based on the ideXlab platform.
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residual stress measurements in a thick dissimilar aluminum alloy friction stir weld
Acta Materialia, 2006Co-Authors: Michael B Prime, Thomas Gnaupelherold, John A Baumann, Richard J Lederich, David M Bowden, Robert J SebringAbstract:Abstract Plates (25.4 mm thick) of aluminum alloys 7050-T7451 and 2024-T351 were joined in a butt joint by friction stir welding (FSW). A 54 mm long test specimen was removed from the Parent Plate, and cross-sectional maps of residual stresses were measured using neutron diffraction and the contour method. The stresses in the test specimen peaked at only about 32 MPa and had the conventional “M” profile with tensile stress peaks in the heat-affected zone outside the weld. The asymmetric stress distribution is discussed relative to the FSW process and the regions of highest thermal gradients. The general agreement between the two measurement techniques validated the ability of each technique to measure the low-magnitude stresses, less than 0.05% of the elastic modulus. Subtle differences between the two were attributed to spatial variations in the unstressed lattice spacing (d0) and also intergranular strains affecting the neutron results. The FSW stresses prior to relaxation from removal of the test specimen were estimated to have been about 43 MPa, demonstrating the ability of FSW to produce low-stress welds in even fairly thick sections. To avoid the estimated 25% stress relaxation from removing the test specimen, the specimen would have had to be quite long because the St. Venant’s characteristic distance in this case was more related to the transverse dimensions of the specimen than to the Plate thickness.
A E Paterson - One of the best experts on this subject based on the ideXlab platform.
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fatigue performance of 6261 t6 aluminium alloy constant and variable amplitude loading of Parent Plate and welded specimens
International Journal of Fatigue, 1997Co-Authors: M N James, A E PatersonAbstract:Abstract The work reported in this paper is a summary of the results obtained from several projects run over a five year period. A number of thrusts were encompassed in the project scope, which was to examine the fatigue strength of extruded 6261-T6 I-beams with centrally located, welded cover Plates under constant amplitude (CA) and variable (two-level repeated block) amplitude (VA) loading. The CA part of the work examined the effect of cover Plate geometry, specimen size, thermal and vibratory stress relief, and differences in fabrication quality on fatigue performance. A number of cases were identified which gave rise to cross-overs in performance in moving from shorter to longer fatigue lives. The aim of the VA part of the work was to identify situations which might give rise to fatigue lives shorter than predicted by linear damage summation models, such as Miner's rule. Two such cases were identified: specimens which had been subjected to vibratory stress relief; and specimens in which weld `quality' (as assessed by profile, heat affected zone hardness, extent and microstructure) varied. Explanations for these observations are proposed and supported by interpretation of a two-level block of small fatigue crack growth.
