Yangtze River Delta G60 laser alliance guide
据悉，日本东京大学科研人员报道了激光焊接策略对减少金属间化合物形成和残余应力的影响。 相关研究以“Effect of laser welding strategy for reducing intermetallic compound formation and residual stress”为题发表在《Precision Engineering》上。
Bright spot:
-The electroless nickel layer (electroless nickel plating) avoids the formation of aluminum-copper compounds during the laser welding process.
-By controlling the pre-heat treatment temperature of the metal before laser welding, the residual thermal stress can be reduced.
– The tensile strength of the welded joint depends on the speed of the laser scan during the welding process.
-The contact area of the aluminum-copper interface affects the residual thermal stress after laser welding.
Reducing the weight of vehicles and reducing CO2 emissions are essential for the further development of the automotive industry. Aluminum is a lightweight material that can replace copper in automotive electronics, so laser welding of aluminum and copper is a subject of extensive research. In this study, we investigated the influence of laser strategies on aluminum-copper laser welding while preventing the formation of brittle aluminum-copper intermetallic compounds. The aluminum and copper plates used in the experiment were 20 mm in length and 0.3 mm and 1 mm thick, respectively. A continuous-wave laser with a power of 500 W and a spot radius of 150 μm is used to irradiate the aluminum surface at different scanning speeds. An electroless nickel plating layer was used as a buffer between aluminum and copper, and the experimental results showed that the nickel plating layer could prevent copper surface damage and the formation of aluminum-copper compounds during laser welding. In addition, the simulation and experimental results show that the residual thermal stress after laser welding can be reduced by heat treatment at different temperatures before laser irradiation.
Keywords: laser welding; intermetallic compounds; dissimilar metal welding; residual thermal stress; finite element method; Electroless nickel plating
Figure 1.Laser melting strategies: (a) single-point melting and (b) in-scan melting.
Figure 2.Fracture force measurements.
Figure 3.Schematic diagram of the simulation model
Figure 4.Aluminum-copper interface.
Figure 5.Point laser irradiation: (a) simulation model and (b) experiment.
Figure 6.Maximum depth of the melted area at different laser scanning speeds.
Figure 7.Length of copper surface aluminum melt contacts at different scan speeds.
Figure 8.Simulated melting diameters of (a) copper and (b) aluminum, and distances from the laser origin to the aluminum boundary at different scan speeds.
Figure 9.Simulated temperatures at which the laser melts aluminum (upper layer) and copper (lower layer) at different scan speeds and origin position (L0).
Figure 10.SEM images and EDX analysis of laser irradiation of aluminum, electroless nickel plating, and copper at different scan speeds.
Figure 11.Maximum RTS of aluminum surface after laser irradiation at different fixed positions at room temperature (300 K).
Fig. 12.(a) joint fracture and (b) base metal fracture in a tensile test of a laser-welded aluminum-copper workpiece.
This study explores the effects of laser strategy and ambient temperature on RTS, surface deformation, and intermetallic compound formation. A three-dimensional (3D) model was built and the temperature field at different laser scanning speeds was analyzed. In addition, laser welding of aluminum and copper is challenging, mainly due to the formation of brittle intermetallic compounds at the weld interface. Therefore, in the experiment, a 10 μm electrolytic-free nickel buffer layer was added between the aluminum and copper plates to avoid the formation of aluminum-copper compounds, and the distribution of RTS after laser scanning was calculated in the simulation. In addition, taking into account the effect of RTS on the welded components, a preheat treatment is also applied to reduce the RTS generated during the welding process. Prior to laser welding, the aluminum-copper plate is heated to different temperatures, and the RTS generated at different initial temperatures is calculated to determine the most suitable temperature range for heat treatment to reduce the RTS generated during the welding process.
Paper Links:
https://doi.org/10.1016/j.precisioneng.2024.03.001
Yangtze River Delta G60 Laser Alliance Chen Changjun reprinted!
At the same time, welcome to the 2nd Conference on the Application of Laser Intelligent Manufacturing in the Energy Storage Industry held by the Yangtze River Delta G60 Laser Alliance in Nanjing (Nanjing, April 23-25, 2024)