Mechanisms of dynamic recrystallization in aluminum alloys

Mechanisms of dynamic recrystallization operating at severe plastic deformation in a wide temperature range are reviewed for aluminum alloys. The main mechanism of grain refinement in all aluminum alloys is continuous dynamic recrystallization (CDRX). Temperature, deformation process and distribution of secondary phases strongly affect the CDRX mechanism. Initial formation of geometrically necessary boundaries (GNBs) and a dispersion of nanoscale particles accelerate CDRX facilitating the formation of a 3D network of low-angle boundaries (LAB) followed by their gradual transformation to high-angle boundaries (HAB

Strengthening mechanisms in a Zr-modified 5083 alloy deformed to high strains

The effect of extensive grain refinement through equal-channel angular processing (ECAP) at 300°C on the mechanical properties was examined in a Zr-modified 5083 aluminum alloy. It was shown that any increase in the yield stress (YS) by increasing the number of pressings was attributed to additional contributions from three strengthening mechanisms :(i) grain boundary strengthening related to the size of the crystallites bounded by deformation-induced high-angle boundaries (HAB), (ii) dislocation strengthening related to highly increased dislocation density and(iii)solute strengthening related to promoting dynamic strain aging (DSA) by intense plastic strainin

Effect of friction-stir welding on the microstructure and mechanical properties of an Al-Mg-Si alloy

In this work, sheets of an Al-Mg-Si alloy were joined by double-side friction stir welding and tempered by standard post-weld artificial aging. The combination of relatively high FSW tool rotation and welding speed with subsequent post-weld artificial aging allowed obtaining welds with high joint efficienc

Deformation structures and strengthening mechanisms in an Al-Mg-Sc-Zr alloy

The deformation structures, mechanical properties and strengthening mechanisms of an Al-5.4 Mg-0.4 Mn-0.2Sc-0.09Zr alloy subjected to equal-channel angular pressing (ECAP) for 12 passes at 573 K (300 C) were studied. The yield stress (YS) increased gradually with increasing strain from 245 to 350 MPa, and the ultimate tensile strength (UTS) was nearly independent of the strai

Tensile behavior of friction-stir welded Al-Mg-Si alloy

In this work, digital-image-correlation technique was applied to examine an evolution of strain distribution during transverse tensile tests of friction-stir welded (FSW) Al-Mg-Si allo

Friction stir welding of an Al-Mg-Sc-Zr alloy with ultra-fined grained structure

Effect of friction stir welding (FSW) on mechanical properties and microstructure of Al-5.4Mg- 0.2Sc-0.1Zr sheets with ultra-fined grained (UFG) structure was studied. The UFG-sheets were produced by equal-channel angular pressing (ECAP) followed either by cold or hot rolling. FSW was found to be very effective for retaining the UFG microstructure as well as constituent coherent nano-scale dispersoids in the welded material. Despite the preservation effect, however, the essential material softening was observed in the weld zone. This was attributed to the recrystallization occurring during FSW. The joint efficiency for yield strength of the obtained friction stir welds was found to be 81% in the hot rolled condition and only 55% in the cold rolled state. The relatively low joint efficiency was associated with the recrystallization softening as well as with the formation of a specific “kissing bond” defect in the stir zon

Cryogenic properties of Al-Mg-Sc-Zr friction-stir welds

In this work, the effect of friction-stir welding (FSW) on the microstructure and cryogenic properties of an Al-Mg-Sc-Zr alloy was studied. The produced friction-stir joints demonstrated both excellent static and dynamic mechanical properties at cryogenic temperatures. The joint efficiency for the yield strength during transverse tensile tests was in the range of 95–100%, whereas the impacts fracture toughness in the stir zone was found to be superior compared with that in the base material. The high level of the mechanical properties was attributed to the preservation of Al3(Sc,Zr) dispersoids, extensive grain refinement and the breaking of the continuous grain boundary network of the coarse Al6Mn particles during FS

Abnormal grain growth in a double-sided friction-stir welded Al-Mg-Si alloy

In this work, a standard T6 tempering (involving solution annealing followed by artificial aging) was employed to a fine-grained Al-Mg-Si alloy produced by double-sided friction-stir welding (FSW). The material was found to exhibit abnormal grain growth, thus demonstrating a relatively low thermal stability. The kinetics of abnormal grain growth in the joint was studie