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.

scholarly journals Through-Thickness Residual Stresses, Microstructure, and Mechanical Properties of Electron Beam-Welded CA6NM Martensitic Stainless Steel after Postweld Heat Treatment

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Sheida Sarafan ◽  
Priti Wanjara ◽  
Jean-Benoît Lévesque ◽  
Javad Gholipour ◽  
Henri Champliaud ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Stainless Steel ◽  
Electron Beam ◽  
Residual Stresses ◽  
Tensile Properties ◽  
Martensitic Stainless Steel ◽  
Postweld Heat Treatment ◽  
Image Correlation ◽  
Postweld Heat

In this study, the integrity of electron beam- (EB-) welded CA6NM—a grade of 13% Cr-4% Ni martensitic stainless steel—was assessed through the entire joint thickness of 90 mm after postweld heat treatment (PWHT). The joints were characterized by examining the microstructure, residual stresses, global mechanical properties (static tensile, Charpy impact, and bend), and local properties (yield strength and strain at fracture) in the metallurgically modified regions of the EB welds. The applied PWHT tempered the “fresh” martensite present in the microstructure after welding, which reduced sufficiently the hardness (<280 HV) and residual stresses (<100 MPa) to meet the requirements for hydroelectric turbine assemblies. Also, the properties of the EB joints after PWHT passed the minimum acceptance criteria specified in ASME sections VIII and IX. Specifically, measurement of the global tensile properties indicated that the tensile strengths of the EB welds in the transverse and longitudinal directions were on the same order as that of the base metal (BM). Evaluation of the local tensile properties using a digital image correlation (DIC) methodology showed higher local yield strengths in the fusion zone (FZ) and heat-affected zone (HAZ) of 727 MPa and 740 MPa, respectively, relative to the BM value of 663 MPa. Also, the average impact energies for the FZ and HAZ were 63 J and 148 J, respectively, and attributed to the different failure mechanisms in the HAZ (dimples) versus the FZ (quasi-cleavage consisting of facets and dimples). This study shows that the application of PWHT plays an important role in improving the weld quality and performance of EB-welded CA6NM and provides the essential data for validating the design and manufacturing process for next-generation hydroelectric turbine products.

Effects of Postweld Heat-Treatment on Girth Weld Tensile Property and Microstructure of High-Frequency Electric Resistance Welded Pipe for API X80 Grade Casing Pipe

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Sota Goto ◽  
Shunsuke Toyoda ◽  
Shinsuke Ide ◽  
Yukihiko Okazaki ◽  
Kota Nakashima
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Base Metal ◽  
High Frequency ◽  
Postweld Heat Treatment ◽  
Small Scale ◽  
Electric Resistance ◽  
Heat Treated ◽  
Welded Pipe ◽  
Postweld Heat

The girth weld tensile properties of API X80 grade high-frequency electric resistance welded (HFW) steel pipe for surface casing with the chemical composition of 0.05C–1.6Mn–0.06Nb (mass %) and the diameter of 558.8 mm and wall thickness of 25.4 mm were investigated by simulated postweld heat-treatment (PWHT). The tensile specimens taken from girth butt welded pipe were heat-treated under the conditions of 625 °C × 2 h and 675 °C × 2 h in an air furnace in order to simulate PWHT of casing products. The result of the girth weld tensile test of the heat-treated specimens showed that yield strength and tensile strength decreased very little and these properties sufficiently satisfied the API X80 specification. The change in strength due to heat treatment was discussed based on microscopic observation of the submicrostructures of the base metal by the electron back-scattered diffraction (EBSD) technique, transmission electron microscopy, X-ray diffraction (XRD), and the extraction residue precipitate classification method. The authors concluded that the fine NbC with a diameter of 12–18 nm, which precipitated during the heat treatment, prevented the decrease of strength due to the slight grain growth and dislocation recovery associated with PWHT. Additionally, the effect of PWHT conditions was evaluated by using small-scale laboratory specimens obtained from the base metal. Tensile properties were summarized as a function of the tempering parameter. As a result, strength remained almost constant at the tempering parameter equivalent to the PWHT conditions of 625 °C × 16 h.

KAISER ALUMINUM ALLOY 2219

Alloy Digest ◽  
1999 ◽  
Vol 48 (2) ◽  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminum Alloy ◽  
Postweld Heat Treatment ◽  
High Strength ◽  
Heat Treating ◽  
Kaiser Aluminum ◽  
Structural Applications ◽  
Aluminum Alloy 2219 ◽  
Postweld Heat

Abstract Kaiser Aluminum Alloy 2219 has good machinability and good mechanical properties. The alloy is typically used in high-temperature structural applications and is also used in high-strength weldments where postweld heat treatment can be employed. This datasheet provides information on composition, physical properties, hardness, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: AL-358. Producer or source: Tennalum, A Division of Kaiser Aluminum.

scholarly journals Effect of Postweld Heat Treatment on Microstructure, Hardness, and Tensile Properties of Laser-Welded Ti-6Al-4V

2012 ◽  
Vol 43 (11) ◽  
pp. 4171-4184 ◽  
Author(s):  
Abu Syed H. Kabir ◽  
Xinjin Cao ◽  
Javad Gholipour ◽  
Priti Wanjara ◽  
Jonathan Cuddy ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Tensile Properties ◽  
Postweld Heat Treatment ◽  
Postweld Heat

INVESTIGATION OF PULSE FREQUENCY ON FUSION ZONE CHARACTERISTICS OF GTA WELDED AZ31B MAGNESIUM ALLOY JOINTS

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Subravel V
Keyword(s):  
Magnesium Alloy ◽  
Tensile Properties ◽  
Fusion Zone ◽  
Welding Speed ◽  
Pulse Frequency ◽  
Pulsed Current ◽  
Az31b Magnesium Alloy ◽  
Gas Tungsten Arc ◽  
Gas Tungsten ◽  
Different Levels

In this investigation an attempt has been made to study the effect of welding on fusion characteristics of pulsed current gas tungsten arc welded AZ31B magnesium alloy joints. Five joints were fabricated using different levels of welding speed (105 mm/min –145 mm/min). From this investigation, it is found that the joints fabricated using a welding speed of 135 mm/min yielded superior tensile properties compared to other joints. The formation of finer grains and higher hardness in fusion zone and uniformly distributed precipitates are the main reasons for the higher tensile properties of these joints

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