Double-side friction stir welding of thick magnesium alloy: microstructure and mechanical properties

Weng, Fei; Liu, Yongfeng; Chew, Youxiang; Lee, Bing Yang; Ng, Fern Lan; Bi, Guijun

doi:10.1080/13621718.2019.1706810

Cited by 24 publications

(8 citation statements)

References 40 publications

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“…They observed the formation of random crystallographic texture in DS‐FSW which improved the strength and ductility of the joints. Weng et al [ 18 ] in their study on DS‐FSW of Mg alloy plates of 20 mm thickness observed the finer equiaxed grains in overlap region and similar texture distribution and comparative hardness with parent material.…”

Section: Introductionmentioning

confidence: 97%

Effect of microstructural variation on strain localization in double‐sided friction stir welded AA6061‐AA7075 joints

Garg

Bhattacharya

2022

Strain

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In friction stir welding (FSW), the inhomogeneous microstructure significantly affects the mechanical performance of the joints. The present study investigates the influence of microstructural asymmetry along the thickness on strain localization during tensile test using the digital image correlation technique and fracture morphology for double‐sided FSW (DS‐FSW) AA6061‐AA7075 joints. In top and bottom slices of the transverse tensile sample, nonhomogenous strain localization is noted in heat affected zone (HAZ) of the advancing side (AS), that is, AA6061‐T6, and also presents higher tensile strength. However, in the middle slice of the transverse sample, larger region including thermo‐mechanically affected zone and HAZ undergoes strain localization and exhibits higher elongation at failure. In longitudinal specimens, the strain distribution is homogeneous up to uniform elongation followed by strain concentration at a localised region and fracture. Electron backscatter diffraction revealed that the extent of dynamic recrystallization on the retreating side (AA7075‐T61) is higher than that observed on the AS of the weld. The grain orientation spread map showed a high fraction of recrystallized grains at the weld centre. Presence of major shear textures components B/Btrue¯ and C both below the tool shoulder and weld centre regions are observed from pole figures. The recrystallized texture components P ({011}<112>), Goss ({110}<001>), Rotated Goss ({110}<110>), Cube ({001}<100>) and shear texture ({001}<110>) components is also noted at the weld centre. Middle slice both for longitudinal and transverse sample showed the finest dimple size on the fracture surfaces. The strain localization behaviour and tensile performance assessed for transverse and longitudinal samples can be helpful to find the load orientation dependency and safe design of DS‐FSW joints.

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Section: Introductionmentioning

confidence: 97%

Effect of microstructural variation on strain localization in double‐sided friction stir welded AA6061‐AA7075 joints

Garg

Bhattacharya

2022

Strain

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“…Increasing interest has been seen, especially over the past two decades, in solving problems related to joining of various types of magnesium alloys [13][14][15][16][17][18][19][20]. Porosity [13,14] and hot cracking [15,21] were identified as major problems in welding of magnesium alloys.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Cracking in Laser Welding of Magnesium Alloy AZ91D

Zhou

Aprilia

Mark

2021

Metals

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Considerable research has been carried out to study the laser welding of magnesium alloys. However, the studies are mainly devoted to butt welding, and there has been limited information in the published literature concerning the bead-on-plate laser welding of AZ91D, even though bead-on-plate welding is required for the repair of cast AZ91D parts with surface defects. In the present investigation, surface cracking of the weld metal was observed when an AZ91D magnesium alloy was bead-on-plate welded using the laser welding method. This paper presents the experimental results and analyses to show that the cracking is “solidification cracking” initiated from the weld surface under high thermal stresses. This is in contrast to the “liquation cracking” observed in heat affected zones in tungsten inert gas welding of the same magnesium alloy. Laser power was found to be one of the main factors affecting the distance of the crack propagation. The higher laser power resulted in longer crack propagation distance into the weld metal. It is demonstrated that hot cracking could be avoided by lowering the laser power and welding speed.

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“…On the other hand, the FSW of thick Mg extruded flats poses much greater difficulty because of the brittle nature of Mg alloys. Yet, progress towards thick section FSW of magnesium alloys is also being made, as few studies have recently been reported in this regard [22]. Such progress is largely directed towards weight reduction in aircrafts and automobiles to improve fly-to-buy ratios and fuel economies.…”

Section: Introductionmentioning

confidence: 99%

Friction Stir Welding of Thick Plates of 4Y3Gd Mg Alloy: An Investigation of Microstructure and Mechanical Properties

et al. 2021

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Applications of non-ferrous light metal alloys are especially popular in the field of aerospace. Hence it is important to investigate their properties in joining processes such as welding. Solid state joining process such as friction stir welding (FSW) is quite efficient for joining non-ferrous alloys, but with thick plates, challenges increase. In this study, Mg alloy plates of thickness 11.5 mm were successfully welded via single-pass FSW. Due to the dynamic recrystallization, grain size in the stir zone was reduced to 16 µm which is ≈15 times smaller than the parent material. The optimized rotational speed and traverse speed for optimum weld integrity were found to be 710 rpm and 100 mm/min, respectively. A sound weld with 98.96% joint efficiency, having an Ultimate Tensile Strength (UTS) of 161.8 MPa and elongation of 27.83%, was accomplished. Microhardness of the nugget was increased by 14.3%.

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Double-side friction stir welding of thick magnesium alloy: microstructure and mechanical properties

Cited by 24 publications

References 40 publications

Effect of microstructural variation on strain localization in double‐sided friction stir welded AA6061‐AA7075 joints

Effect of microstructural variation on strain localization in double‐sided friction stir welded AA6061‐AA7075 joints

Mechanisms of Cracking in Laser Welding of Magnesium Alloy AZ91D

Friction Stir Welding of Thick Plates of 4Y3Gd Mg Alloy: An Investigation of Microstructure and Mechanical Properties

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