Laser-arc hybrid welding of wrought to selective laser molten stainless steel

Laser welding has been considered as a promising method to join sintered NdFeB permanent magnets thanks to its high precision and productivity. However, the influences of laser welding on the magnetic property of NdFeB are still not clear. In the present paper, the effects of laser power on the remanence (Br) were experimentally investigated in laser spot welding of a NdFeB magnet (N48H). Results show that the Br decreased with the increase of laser power. For the same welding parameters, the Br of magnets, that were magnetized before welding, were much lower than that of magnets that were magnetized after welding. The decrease in Br of magnets after laser welding resulted from the changes in microstructures and, in turn, the deterioration of magnetic properties in the nugget and the heat affected zone (HAZ) in a laser weld. It is recommended that the dimensions of nuggets and HAZ in laser welds of a NdFeB permanent magnet should be as small as possible, and the magnets should be welded before being magnetized in order to achieve a better magnetic performance in practical engineering applications.

Section: Introductionmentioning

confidence: 99%

Influences of Laser Spot Welding on Magnetic Property of a Sintered NdFeB Magnet

Chang

et al. 2016

Section: Diffusion Coefficientmentioning

confidence: 99%

“…Based on the element concentration of a certain distance from the interface, the diffusion coefficient can be calculated by Equation (2). Table 3 exhibits the diffusion coefficients of Ni on both sides of Ni-316L and Ni-4J29 at temperatures varying from 850 • C to 950 • C. The diffusion coefficients of Ni into both sides gradually increased as temperature increased, which conforms to the regulation of Arrhenius Equation (3), but the increase of the 316L side was more obvious.…”

Section: Diffusion Coefficientmentioning

confidence: 99%

“…316L stainless steel (Fe-18Cr-11Ni) is widely used for its low corrosion rate, which is attributed to its inner chromium oxide region and outer mixed iron-nickel oxide region [1,2]. Kovar (Fe-29Ni-17Co) alloys possess the advantages of low-temperature constant expansion, and thermal expansion properties and a good thermal matching performance similar to Si, Ge, and glass, thus obtaining wide application in the electronics industry [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Interfacial Microstructure and Mechanical Properties of Diffusion-Bonded Joints of 316L Stainless Steel and the 4J29 Kovar Alloy Using Nickel as an Interlayer

Song

Jiang

Shao

et al. 2016

316L stainless steel ) and a Kovar (Fe-29Ni-17Co or 4J29) alloy were diffusion-bonded via vacuum hot-pressing in a temperature range of 850-950 • C with an interval of 50 • C for 120 min and at 900 • C for 180 and 240 min, under a pressure of 34.66 MPa. Interfacial microstructures of diffusion-bonded joints were characterized by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive spectroscopy (EDS). The inter-diffusion of the elements across the diffusion interface was revealed via electron probe microanalysis (EPMA). The mechanical properties of the joints were investigated via micro Vickers hardness and tensile strength. The results show that an Ni interlayer can serve as an effective diffusion barrier for the bonding of 316L stainless steel and the 4J29 Kovar alloy. The composition of the joints was 316L/Ni s.s (Fe-Cr-Ni)/remnant Ni/Ni s.s (Fe-Co-Ni)/4J29. The highest tensile strength of 504.91 MPa with an elongation of 38.75% was obtained at 900 • C for 240 min. After the width of nickel solid solution (Fe-Co-Ni) sufficiently increased, failure located at the 4J29 side and the fracture surface indicated a ductile nature.

“…In this work, fiber laser welding was used to conduct the experiment. In recent years, laser-arc hybrid welding also attracted researchers' interest [12,17,21]. Zhang et al [12] compared the microstructure and properties of MIG welding joint and laser-MIG hybrid welding joints.…”

Section: Introductionmentioning

confidence: 99%

Study on the Size Effects of H-Shaped Fusion Zone of Fiber Laser Welded AZ31 Joint

Zhang

et al. 2018

There are two kinds of typical cross-section profiles for the fusion zone (FZ) of a laser welded thin section joint, i.e., a V-shaped cross-section and an H-shaped cross-section. Previous researches indicated that tensile strength of the V-shaped joint was lower than that of the H-shaped one due to the greater heterogeneity of strain distribution on the V-shaped joint during tensile process. In this work, impacts of the aspect ratio of FZ on the mechanical properties of laser welded thin section joints with an H-shaped cross-section profile were investigated. Welding conditions corresponding to two typical H-shaped joints (i.e., W narrower with a narrower FZ, and W wider with a wider FZ) were decided through a laser welding orthogonal experimental plan. Then, the microstructure and properties of both joints were examined and compared. The results show that the tensile strength of joint W narrower and joint W wider was about 72% and 80.9% that of the base metal, respectively. Both joints fractured in the FZ during tensile processes. The low-cycle fatigue life of the base metal, the joint W narrower and the joint W wider were 3377.5 cycles, 2825 cycles and 3155.3 cycles, respectively. By using high-speed imaging, it was found that the fatigue crack of joint W narrower initiated and propagated inside the fusion zone, while the fatigue crack of the joint W wider initiated at the edge of the base metal and propagated for a distance within the base metal before entering into the fusion zone. This work promoted our understanding about the influence of the weld bead shape on the properties of laser welded thin section joints.