Effects of Residual Stresses and the Post Weld Heat Treatments of TIG Welded Aluminum Alloy AA6061-T651

2012 ◽  
Author(s):  
Mohammad W. Dewan ◽  
Jiandong Liang ◽  
M. A. Wahab ◽  
Ayman M. Okeil
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Residual Stresses ◽  
Tensile Properties ◽  
Ultrasonic Testing ◽  
Micro Hardness ◽  
Weld Defects ◽  
Performance Reduction ◽  
Weld Heat

Heat treatable AA-6061 T651 Aluminum alloys (Al-Mg-Si) have found considerable importance in various structural applications for their high strength to weight ratio and corrosion resistance properties. Weld defects, residual stresses, and microstructural changes are the key factors for the performance reduction as well as failure of welded structures. Tungsten inert gas (TIG/GTAW) welding was carried out on AA-6061 T651 Aluminum Alloy plates using Argon/Helium (50/50) as the shielding gas. Non-destructive phased array ultrasonic testing (PAUT) was applied for the detection and characterization of weld defects and characterization of the mechanical performances. In this study, ultrasonic technique was also used for the evaluation of post-weld residual stresses in welded components. The approach is based on the acoustoelastic effect, in which ultrasonic wave propagation speed is related to the magnitude of stresses present in the materials. To verify the estimated residual stresses by ultrasonic testing, hole-drilling technique was carried out and observed analogous results. The effects of post weld heat treatment (PWHT) on the residual stresses, grain size, micro hardness, and tensile properties were also studied. The grain size and micro hardness were studied through Heyn’s method and Vickers hardness test, respectively. Lower residual stresses were observed in post-weld heat-treated specimens, which also experienced from microstructure and micro hardness studies. The PWHT also resulted enhanced tensile properties for the redistribution of microstructures and residual stresses.

scholarly journals Effects of grain size and dendrite arm spacing on tensile properties of continuous-cast 6061 aluminum alloy billets.

1997 ◽  
Vol 47 (2) ◽  
pp. 98-103 ◽  
Author(s):  
Tomokazu YAMASHITA ◽  
Tooru WATANABE ◽  
Kou NAKAHIRA ◽  
Kenji MATSUDA ◽  
Hiroshi ANADA ◽  
...  
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Continuous Cast ◽  
6061 Aluminum Alloy ◽  
Dendrite Arm Spacing

Characterization of Doped Titanium Oxide Varistor Powder Processed with Latex Binder

2015 ◽  
Vol 1115 ◽  
pp. 133-136
Author(s):  
Shahida Begum ◽  
Ida Rasyada ◽  
Arvin Panimeerselvam
Keyword(s):  
Grain Size ◽  
Silicon Oxide ◽  
Ceramic Materials ◽  
Sem Analysis ◽  
Electrical Performance ◽  
Green Density ◽  
Micro Hardness ◽  
Radial Shrinkage ◽  
Average Grain Size

In the processing of semiconducting electro ceramic materials the use of appropriate binder can lead to improve characteristics of powder which will reduce density gradient in the green body during compaction. The binder system is anticipated to have an influence on the grain growth and microstructure which in turn affect the electrical performance. To investigate this phenomenon, TiO2 powder doped with tungsten oxide (WO3), silicon oxide (SiO2) and bismuth oxide (Bi2O3) was processed with and without various percent of latex binder. The prepared samples were characterized by evaluating the physical properties like green density, fired density, axial and radial shrinkage, micro hardness and compressive strength. It was observed that TiO2 processed with latex binder exhibited higher green density and less axial and radial shrinkage compared to powder processed without binder. However, the binder level did not have any significant influence on the other characteristics of varistor discs. SEM analysis indicated that the average grain size was also influenced by the percent of binder used and but the higher average grain size was obtained for discs without any binder.

The Role of Crystallization of an Intergranular Glassy Phase in Determining Grain Boundary Residual Stresses in Debased Aluminas

1989 ◽  
Vol 170 ◽  
Author(s):  
Nitin P. Padture ◽  
Helen M. Chan ◽  
Brian R. Lawn ◽  
Michael J. Readey
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Residual Stresses ◽  
Glassy Phase ◽  
Analytical Techniques ◽  
Ceramic Materials ◽  
Strength Test ◽  
Second Phase

AbstractThe influence of microstructure on the crack resistance (R-curve) behavior of a commercial debased alumina containing large amounts of glassy phase (28 vol %) has been studied using the Indentation-Strength test. The effect of two microstructural variables, viz. grain size and the nature of the intergranular second phase (glassy or crystalline) has been evaluated. Crystallization of the intergranular glass was carried out in order to generate residual stresses at the grain boundaries, which have been shown to enhance R-curve behavior in ceramic materials. Enhancement of the R-curve behavior was observed with the increase in grain size. However, no effect of the nature of the intergranular second phase on the R-curve behavior, in small and large grain materials, was observed. The results from characterization of these materials using various analytical techniques is presented, together with possible explanations for the observed effects.

Effects of Heat Treatment on the Tensile Properties of Flow-Formed AA6082 Aluminum Alloy Tube

2015 ◽  
Vol 830-831 ◽  
pp. 131-134 ◽  
Author(s):  
Bikramjit Podder ◽  
Chandan Mondal ◽  
G. Gopi ◽  
K. Ramesh Kumar
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Artificial Aging ◽  
Reverse Flow ◽  
Natural Aging ◽  
Alloy Tube ◽  
Treatment Conditions ◽  
Aluminum Alloy Tube

The present study reports the effect of the heat treatment on the tensile properties of the reverse flow-formed AA6082 Aluminum alloy tube. Tensile specimens obtained after each forming pass have been subjected to three different heat-treatment conditions viz., as-flow formed (AFF), as-flow formed followed by artificial aging (170°C/6h) and HT (solutionizing + 170°C/6h) treatments. Characterization of the tensile properties reveals that as-flow formed condition (followed by natural aging) gives the best combination of yield strength, UTS and percentage of elongation. The variations in tensile properties are correlated with microstructure of the materials.

Adhesion and Tensile Properties of a Novel Fiber-Metal Laminate Based on Polypropylene Reinforced with Aramid Fibers.

2014 ◽  
Vol 1611 ◽  
pp. 43-48 ◽  
Author(s):  
Nancy G. González-Canché ◽  
J.G. Carrillo ◽  
R.A. Gamboa
Keyword(s):  
Shear Strength ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Interfacial Adhesion ◽  
Aramid Fiber ◽  
Thin Layers ◽  
Woven Fabric ◽  
Fiber System ◽  
Tensile Characterization

ABSTRACTThe aim of the present study is to analyze interfacial adhesion and characterize the tensile properties of a FML elaborated from thin layers of an aluminum alloy and layers of maleic anhydride modified polypropylene (MAHPP) reinforced with an aramid woven fabric. For the analysis of interfacial adhesion, a microbond test is carried out on the MAHPP-aramid fiber system and a single lap joint test is performed on FML constituent materials, as well as the tensile characterization of the FML and its constituents is conducted accordingly. Microbond testing revealed an improvement in interfacial shear strength for the MAHPP-aramid fiber system in comparison with that of polypropylene-aramid fiber systems reported in the literature. The apparent shear strength between the FML constituent materials is comparable to that for bonding of aluminum with MAHPP. Tensile characterization of the FML and its constituents showed that the FML presented greater tensile strength than the aluminum alloy; and a more ductile behavior in comparison with its individual components due to the degree of adhesion between the constituents which allows the material to deform in unison.

Influence of Weld Defects and Postweld Heat Treatment of Gas Tungsten Arc-Welded AA-6061-T651 Aluminum Alloy

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Mohammad W. Dewan ◽  
M. A. Wahab ◽  
Ayman M. Okeil
Keyword(s):  
Heat Treatment ◽  
Aluminum Alloy ◽  
Tensile Properties ◽  
Postweld Heat Treatment ◽  
Defect Size ◽  
Weld Defects ◽  
Gas Tungsten Arc ◽  
Weld Defect ◽  
Gas Tungsten ◽  
Postweld Heat

Welding defects and the reduction of mechanical performances are the foremost problems for fusion welded aluminum alloys joints. The influences of weld defects and postweld heat treatment (PWHT) on tensile properties of gas tungsten arc (GTA) welded aluminum alloy AA-6061-T651 joints are investigated in this current study. All welded specimens are nondestructively inspected with phased array ultrasonic testing (PAUT) to classify weld defect and measure the projected defects area-ratio (AR). Ultimate tensile strength (UTS) decreased linearly with the increase of the size of weld defect but tensile toughness behaved nonlinearly with defect size. Depending on defect size, defective samples' joint efficiency (JE) varied from 35% to 48% of base metal's (BM) UTS. Defect-free as-welded (AW) specimens observed to have 53% and 34% JE based on UTS and yield strength (YS) of BM, respectively. PWHT was applied on defect-free welded specimens to improve tensile properties by precipitation hardening, microstructures refining, and removal of postweld residual stresses. Solution treatment (ST) (at 540 °C) followed by varying levels of artificial age-hardening (AH) time was investigated to obtain optimum tensile properties. For GTA-welded AA-6061-T651, peak aging time was 5 hr at 180 °C. PWHT specimens showed 85% JE based on UTS and up to a 71% JE based on YS of BM. However, toughness values decreased about 29% due to the presence of precipitate-free fusion zones. The experimental investigations can be used to establish weld acceptance/rejection criteria and for the design of welded aluminum alloy structures.

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