Microstructure and properties of the laser butt welded 1.5-mm thick T2 copper joint achieved at high welding speed

Zhang, Linjie; Zhang, Guifeng; Ning, Jie; Zhang, Xingjun; Zhang, Jianxun

doi:10.1016/j.matdes.2015.09.072

Cited by 57 publications

(16 citation statements)

References 38 publications

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“…X-ray radiographic inspection results showed obvious porosity appeared in the FZ. Considering the high melting point of Mo and its significant tendency of grain coarsening, laser welding technology with the advantages of high energy density is possibly a feasible fusion welding method for Mo alloy [19,20,21,22,23,24].…”

Section: Introductionmentioning

confidence: 99%

Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Xie

Shang

et al. 2019

Materials

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Porosity defects are still a challenging issue in the fusion welding of molybdenum and its alloys due to the pre-existing interior defects associated with the powder metallurgy process. Fiber laser welding of end plug and cladding tube made of nanostructured high-strength molybdenum (NS-Mo) alloy was performed in this work with an emphasis on the role of welding heat input. The distribution and morphology of porosity defects in the welded joints were examined by computed tomography (CT) and scanning electron microscopy (SEM). Preliminary results showed that laser welding of NS-Mo under low heat input significantly reduced the porosity defects in the fusion zone. The results of computed tomography (CT) showed that when the welding heat input decreased from 3600 J/cm (i.e., 1200 W, 0.2 m/min) to 250 J/cm (i.e., 2500 W, 6 m/min), the porosity ratio of the NS-Mo joints declined from 10.7% to 2.1%. Notable porosity defects under high heat input were related to the instability of the keyhole, expansion and the merging of bubbles in the molten pool, among which the instability of the keyhole played the dominant role. The porous defects at low heat input were generated as bubbles released from the powder metallurgy base metal (BM) did not have enough time to overflow and escape.

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Section: Introductionmentioning

confidence: 99%

Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Xie

Shang

et al. 2019

Materials

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“…Laser welding not only has the advantages of high-power density and low-heat input, but also can be carried out in an open environment without vacuum chamber [24][25][26][27][28][29][30][31]. Therefore, laser welding of molybdenum alloy has been studied by many researchers [5][6][7][8][9][10]32].…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Mechanical Properties of a Fiber Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Xie

Shang

et al. 2019

Metals

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Fiber welding of socket-joints made of nanostructured high-performance molybdenum alloy (NS Mo) was carried out to get a better understanding of the role of welding heat input. It was found that low heat input (i.e., high welding speed) resulted in significantly refined grains in the fusion zone (FZ) of fiber laser welded NS Mo joints. When welding heat input decreased from 3600 J/cm (i.e., 1.2 kW, 20 cm/min) to 250 J/cm (i.e., 2.5 kW, 600 cm/min), the tensile strength of welded joints increased from about 250 MPa to about 570 MPa. It was confirmed by energy spectrum analysis that the higher the welding heat input, the higher the oxygen contents at the grain boundary (GB) within the FZ. In addition, the most important reason for poor strength of welded joints of Mo alloys was reported as being that MoO2 was segregated on the grain boundary. Therefore, it was concluded that welding under low heat input (i.e., high welding speed) was able to reduce the segregation degree of MoO2 at the grain boundary by refining grains and increasing the total area of GBs, thus improving the strength of welded joints and reducing the proportion of the intergranular fracture zone in tensile fractures.

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“…Laser welding HAZ is narrow, and forms a good-looking welding seam [20,21,22]. Nevertheless, it is easy to generate gas holes in the welding seam, and the cost of laser welding is high [23]. The laser–TIG hybrid heating source welding not only gives full play to their respective advantages, but also makes up for each other’s deficiencies.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Microstructures of Laser–TIG Welded ME21 Rare Earth Mg Alloy

Song

Zhang

et al. 2019

Materials

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The microstructural and mechanical properties of laser–tungsten inert gas (TIG) hybrid welding of Mg alloy sheets for automobiles are investigated in the present work, including AZ31 and ME21, AZ31 and AZ31, ME21 and ME21, and corresponding comparisons were carried out. The results show that columnar crystals appear in the ME21/ME21 and ME21/AZ31 heat-affected zones, and no columnar crystals formed in the AZ31/AZ31 fusion zone under a constant heat ratio of arc to laser. Heat accumulation in a narrow area and the undercooling degree are the two main factors for the formation of columnar crystal. The ME21/ME21 joint has a tensile strength of up to 185.2 MPa, which is about 81.8% of that of the ME21 base metal (BM-ME21). The tensile strength of the ME21/AZ31 joint (158.8 MPa) is lower than that of the ME21/ME21 joint. The fracture of the ME21/ME21 and ME21/AZ31 joints occurs at the junction of the columnar crystal and the heat-affected zone. The microhardness of the ME21/AZ31 joint presents a low–high–low–high trend from BE-ME21 to BE-AZ31, and the distribution of the ME21/AZ31 welded joint microhardness in the cross-section presents a low–high–low trend. The ME21/ME21 weld seam is composed of an AlCe3 intermetallic compound, Mn particles, and α-Mg, and the ME21/AZ31 weld seam is composed of a α-Mg, Mg17Al12, and AlCe3 intermetallic compound.

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Microstructure and properties of the laser butt welded 1.5-mm thick T2 copper joint achieved at high welding speed

Cited by 57 publications

References 38 publications

Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Effect of Heat Input on Porosity Defects in a Fiber Laser Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Microstructure and Mechanical Properties of a Fiber Welded Socket-Joint Made of Powder Metallurgy Molybdenum Alloy

Mechanical Properties and Microstructures of Laser–TIG Welded ME21 Rare Earth Mg Alloy

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