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

Abstract

a b s t r a c tIn 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 Al 3 (Sc,Zr) dispersoids, extensive grain refinement and the breaking of the continuous grain boundary network of the coarse Al 6 Mn particles during FSW.

Superplasticity of friction-stir welded Al–Mg–Sc sheets with ultrafine-grained microstructure

“…Therefore, the conventional technologies are obviously not appropriate for this processing route. In contrast, the friction-stir welding (FSW) technique enables preservation of the fine-grained structure [10][11][12][13][14] and avoids dissolution of the unique Al 3 Sc dispersoids [7][8][9][14][15][16][17][18][19][20] in the weld zone, making FSW particularly promising for use in the joining of UFG Al-Mg-Sc alloys.…”

“…Therefore, the conventional technologies are obviously not appropriate for this processing route. In contrast, the friction-stir welding (FSW) technique enables preservation of the fine-grained structure [10][11][12][13][14] and avoids dissolution of the unique Al 3 Sc dispersoids [7][8][9][14][15][16][17][18][19][20] in the weld zone, making FSW particularly promising for use in the joining of UFG Al-Mg-Sc alloys.Recent studies have demonstrated that friction-stir processed Al-Mg-Sc alloys exhibit excellent superplastic properties [21][22][23][24][25][26][27][28]. Specifically, the maximum elongation-to-failure value may sometimes exceed 2000% [21, 24, 27].…”

Mechanical Behavior of an Al–Mg–Mn–Sc Alloy with an Ultrafine Grain Structure at Cryogenic Temperatures

“…[1,2] At subzero temperatures, these mechanical characteristics increase linearly with decreasing temperature; [1,[3][4][5][6] this is in contrast to conventional steel materials, which typically lose most of their ductility and toughness below the ductile-brittle transition (DBT) temperature. [1,2] At subzero temperatures, these mechanical characteristics increase linearly with decreasing temperature; [1,[3][4][5][6] this is in contrast to conventional steel materials, which typically lose most of their ductility and toughness below the ductile-brittle transition (DBT) temperature.…”

“…However, in high-strength steels at room temperature, the grain boundary strengthening by refining the grain size to 1 mm or less results in low toughness and low tensile ductility due to reducing the work hardening capacity, although fracture occurs in a ductile manner. [4] Note that the effect of grain size on strength and toughness of steels has been well-examined, [7,8] while a limited number of studies has addressed aluminum alloys. [4] Note that the effect of grain size on strength and toughness of steels has been well-examined, [7,8] while a limited number of studies has addressed aluminum alloys.…”

“…[8,15] In contrast, in the Al-Mg-Sc alloy, the extensive grain refinement by friction stir welding (FSW) in the stir zone enhances strength, ductility, and toughness of hot-rolled material at an ambient temperature, while at 77 K, no remarkable effect of grain size on these mechanical properties in the hot-rolled alloy was found. [10] The aim of the present work is a better understanding of mechanical and fracture behavior of ultrafine grained Al-Mg-Mn-Sc alloy in a range of temperatures from 77 to 293 K. The article is focused on the plastic flow and work-hardening behavior of the alloy to compare with the properties of the same material after different process routes, such as casting, hot rolling, [10] and FSW [4] obtained earlier. [10] The aim of the present work is a better understanding of mechanical and fracture behavior of ultrafine grained Al-Mg-Mn-Sc alloy in a range of temperatures from 77 to 293 K. The article is focused on the plastic flow and work-hardening behavior of the alloy to compare with the properties of the same material after different process routes, such as casting, hot rolling, [10] and FSW [4] obtained earlier.…”