Strong and ductile age-hardening Mg-Al-Ca-Mn alloy that can be extruded as fast as aluminum alloys

2017 ◽  
Vol 130 ◽  
pp. 261-270 ◽  
Author(s):  
T. Nakata ◽  
C. Xu ◽  
R. Ajima ◽  
K. Shimizu ◽  
S. Hanaki ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Age Hardening

scholarly journals Recent advances in the metallurgy of aluminum alloys. Part II: Age hardening

2018 ◽  
Vol 19 (8) ◽  
pp. 688-709 ◽  
Author(s):  
Christophe Sigli ◽  
Frédéric De Geuser ◽  
Alexis Deschamps ◽  
Joël Lépinoux ◽  
Michel Perez
Keyword(s):  
Aluminum Alloys ◽  
Age Hardening ◽  
Recent Advances

Retrogression and Re-aging Heat Treatment: AA7XXX Aluminum Alloys

2019 ◽  
Author(s):  
V. Anil Kumar ◽  
S. Arjun ◽  
R.K. Gupta ◽  
P.V. Venkitakrishnan
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloys ◽  
Industrial Applications ◽  
Age Hardening ◽  
Large Cross Section ◽  
Structural Applications ◽  
The Matrix ◽  
Peak Aged ◽  
Aged Temper ◽  
Short Time

Retrogression and re-aging (RRA) treatment was introduced to increase the stress corrosion cracking (SCC) resistance while retaining the strength attainable in T6 (peak aged) temper. Retrogression is a short-term heat treatment at an elevated temperature wherein a partial dissolution of metastable precipitates occurs, which are responsible for the hardening. During the next step, the material is re-aged in the regime of typical age hardening parameters to restore the strength with improved ductility. Response of RRA treatment has been reported on AA7XXX series Aluminum alloys such as AA7075, AA7050, AA7150, AA7049, and AA7010. Studies have been done on the effect of RRA on microstructure, mechanical properties such as tensile and hardness, corrosion, exfoliation corrosion, and SCC resistance by various researchers. The key characteristic of RRA is retrogression, which makes the re-precipitation in the matrix and coarsening of grain boundary precipitates such as MgZn2, η′. The retrogression treatment however requires high temperature and a short time, which limits the industrial application of RRA, especially in the heat treatment of the components with large cross section, due to the inherent thermal conductivity limitations. Hence, further work needs to be done in this area to apply this specialized heat treatment for industrial applications. This article brings out a comprehension of the changes in microstructure, tensile properties, and corrosion resistance of the various commonly used AA7XXX Aluminum alloys in structural applications with RRA heat treatment. The future scope of the work in RRA heat treatment is also discussed in this article.

The Characterization and Conservation of Aged Aluminum Alloys: Buckminster Fuller's Dymaxion House

2002 ◽  
Vol 712 ◽  
Author(s):  
Karen A. Trentelman ◽  
James Ashby ◽  
William T. Donlon
Keyword(s):  
Aluminum Alloys ◽  
Structural Integrity ◽  
Primary Aluminum ◽  
Grain Structure ◽  
Age Hardening ◽  
Original Structure ◽  
Visual Appearance ◽  
Henry Ford ◽  
Buckminster Fuller ◽  
Cladding Layers

ABSTRACTThe Dymaxion House is a unique historic dwelling structure designed by Buckminster Fuller. Built in the 1940s, the house was constructed of modern materials, most notably aluminum, which formed the walls, roof and many of the structural elements. The challenge faced in reconstructing the Dymaxion House at Henry Ford Museum & Greenfield Village was to preserve the original structure as much as possible while simultaneously accommodating the needs of exhibition (i.e. to restore the visual appearance and ensure sufficient structural integrity to allow the entrance of visitors). The primary aluminum alloys used in the house are equivalent to the modern alloy designations 2014 and 2024; both extruded forms and Alclad sheets were used. The alloy composition, age-hardening characteristics, cladding layers, grain structure and corrosion products of the aged aluminum components of the Dymaxion House have been studied. The results of these studies were used in consultation with conservators, engineers and corrosion scientists to determine the most appropriate course of treatment.

Three Strategies to Achieve Concurrent Strengthening by Ultrafine-Grained and Precipitation Hardenings for Severely Deformed Age-Hardnable Aluminum Alloys

2016 ◽  
Vol 1135 ◽  
pp. 161-166 ◽  
Author(s):  
Shoichi Hirosawa ◽  
Yong Peng Tang ◽  
Zenji Horita ◽  
Seung Won Lee ◽  
Kenji Matsuda ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Volume Fraction ◽  
High Pressure Torsion ◽  
Equivalent Strain ◽  
Age Hardening ◽  
Cu Alloy ◽  
Ultrafine Grained ◽  
Δ Phase ◽  
Microalloying Elements ◽  
Wrought Aluminum Alloys

In this paper, comprehensive studies on the age-hardening behavior and precipitate microstructures of severely deformed and then artificially aged aluminum alloys have been conducted to clarify whether or not concurrent strengthening by ultrafine-grained and precipitation hardenings can be achieved. From our graphically-illustrated equivalent strain dependence of both the attained hardness and increment/decrement in hardness during aging (i.e. age-hardenability), three strategies to maximize the combined processing of severe plastic deformation and age-hardening technique are proposed. (1) Lowering of aging temperature and (2) utilization of microalloying elements can improve not only the attained hardness but also the age-hardenability of high-pressure torsion (HPT) specimens of Al-Mg-Si (-Cu) alloy due to the increased volume fraction of transgranular precipitates. A further increase in hardness can be achieved by (3) taking advantage of spinodal decomposition for HPTed Al-Li-Cu alloy, in which nanoscale precipitates of δ’ phase are successfully formed within ultrafine grains, irrespective of the higher number density of grain boundaries. The attained hardness of >HV290 in the latter alloy is almost the highest among conventional wrought aluminum alloys, and therefore our proposed strategies will be useful for designing concurrently strengthened severely-deformed age-hardenable aluminum alloys.

Effects of Post Weld Heat Treatments (PWHT) on Friction Stir Welded AA2219-T87 Joints

2017 ◽  
Author(s):  
Mohammad W. Dewan ◽  
Muhammad A. Wahab ◽  
Khurshida Sharmin
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Yield Strength ◽  
Solution Treatment ◽  
Welding Process ◽  
Alloying Elements ◽  
Age Hardening ◽  
Experimental Program ◽  
Friction Stir ◽  
Aging Period

Friction Stir Welding (FSW) offers significantly better performance on aluminum alloy joints compared to the conventional fusion arc welding techniques; however, plastic deformation, visco-plastic flow of metals, and complex non-uniform heating cycles during FSW processes, result in dissolution of alloying elements, intrinsic microstructural changes, and post-weld residual stress development. As a consequence, about 30% reduction in ultimate strength (UTS) and 60% reduction in yield strength (YS) were observed in defect-free, as-welded AA2219-T87 joints. PWHT is a common practice to refine grain-coarsened microstructures which removes or redistributes post-weld residual stresses; and improves mechanical properties of heat-treatable welded aluminum alloys by precipitation hardening. An extensive experimental program was undertaken on PWHT of FS-welded AA2219-T87 to obtain optimum PWHT conditions and improvement of the tensile properties. Artificial age-hardening (AH) helped in the precipitation of supersaturated alloying elements produced around weld nugget area during the welding process. As a result, an average 20% improvement in YS and 5% improvements in UTS was observed in age-hardened (AH-170°C-18h) specimens as compared to AW specimens. To achieve full benefit of PWHT, solution-treatment followed by age-hardening (STAH) was performed on FS-welded AA2219-T87 specimens. Solution-treatment (ST) helps in the grain refinement and formation of supersaturated precipitates in aluminum alloys. Age-hardening of ST specimens help in the precipitation of alloying elements around grain boundaries and strengthen the specimens. Optimum aging period is important to achieve better mechanical properties. For FS-welded AA2219-T87 peak aging time was 5 hours at 170°C. STAH-170°C -5h treated specimens showed about 78% JE based on UTS, 61% JE based on yield strength, and 36% JE based on tensile toughness values of base metal.

Age-Hardening Response of Mg-Al-Sn Alloys

2015 ◽  
Vol 828-829 ◽  
pp. 250-255
Author(s):  
Abu Syed Humaun Kabir ◽  
Jing Su ◽  
Mehdi Sanjari ◽  
In Ho Jung ◽  
Stephen Yue
Keyword(s):  
Electron Microscope ◽  
Aluminum Alloys ◽  
Scanning Electron Microscope ◽  
Magnesium Alloys ◽  
Isothermal Aging ◽  
Precipitation Hardening ◽  
Metallic Alloys ◽  
Mg Alloys ◽  
Age Hardening ◽  
Scanning Electron

Precipitation hardening has been used before as one of the most effective strengthening methods for many metallic alloys. However, this method has not been studied completely in magnesium alloys, and the numbers of precipitation hardenable wrought Mg alloys are still very limited compared to aluminum alloys and steels. The age hardening responses of Mg-Al-Sn alloys in cast-homogenized condition were investigated by isothermal aging at 200°C for prolonged time. It was found that hardness can be improved significantly for the alloy with higher amounts of tin. The improvement in hardness was reasoned by the formation of precipitates. The shapes and morphology of the precipitates were different depending on the orientations of the grains. The precipitates were characterized by scanning electron microscope.

Modelling of Phase Transformation During Homogenization of Ternary Aluminum Alloys

2000 ◽  
Vol 652 ◽  
Author(s):  
Thorsten Hofmeister ◽  
Klaus Greven ◽  
Andreas Ludwig ◽  
Peter R. Sahm
Keyword(s):  
Phase Transformation ◽  
Aluminum Alloys ◽  
Ternary Alloys ◽  
Age Hardening ◽  
Macroscopic Model ◽  
Coupled Modeling ◽  
Dendrite Solidification ◽  
Homogenization Model ◽  
Mould Casting ◽  
Cast Parts

ABSTRACTThe microstructure determines for the most part mechanical properties of castings. This is the case especially with age-hardening aluminum alloys. To predict the phase transformation in cast parts during and after solidification a sophisticated approach to a coupled modeling of various simulation phenomena is presented. This approach couples a diffusion equation solver which considers the online estimation of thermodynamic equilibria with a macroscopic model for temperature calculation. The coupled micro-model predicts the dendrite solidification of ternary alloys. To simulate the phase transformation in temperature zones below solidification a homogenization model is added. Permanent mould casting experiments with ternary aluminum alloys are used to validate these models.

Sign in / Sign up

Export Citation Format

Share Document