Experimental And Material Properties Of Laser Bending Of Copper-Steel Laminated Plate

Copper-steel laminated plate is a new type of laminated composite material with high efficiency and energy saving.It has the advantages of both base and cladding.Laser bending technology is a flexible forming technology,in which high-energy laser beam scans the surface of sheet metal,and the thermal stress induced by high temperature causes the expected plastic deformation in the laser scanning area.There are abrupt changes in material properties at the transition layer of copper-steel laminated plate.So there are great differences and technical difficulties in laser energy transfer and bending compatibility between the layers.In this paper,the laser coordinated bending of copper-steel laminated plate(T2/SPCC)is studied by means of temperature gradient mechanism parameters and material characterization.The main research work is as follows:(1)Laser coordinated bending experiment and Warping Deformation suppression of copper-steel laminated plate.The bending angle of copper-steel laminated plate is correlated with laser power P,scanning speed v,scanning times n,defocusing Z and plate width W.The bending law of copper-steel laminated plate with laser parameters and plate parameters was studied systematically.In view of the warping phenomenon in laser bending process of copper-steel laminated plate,a method of combining “three-stage variable speed + local energy compensation” is proposed,which can reasonably adjust the energy input of each section of the scanning line,reduce the warpage of laser bending copper-steel laminated plate and improve the processing accuracy.(2)Microstructure and interfacial characteristics of laser bending zone of copper-steel laminated plate were analyzed.Before and after laser processing,the macro-interface of copper-steel interface changed from small waveform of substrate to large waveform with better bonding quality.The thickness of the bending zone of the laminated plate increases in varying degrees,which affects the surface roughness.Recovery and recrystallization occur in laser bending zone of laminated plate,grain size increases slightly in copper bending zone,grain refinement occurs in carbon steel bending zone,and the cross section of grain refinement zone presents a parabolic shape with obvious opening upward.The thickness of interfacial transition layer of substrate is 1.90 μm,and the thickness of interfacial transition layer increases from 2.24 μm to 6.51 μm when scanning times increase from 30 to 90.There is no oxygen element aggregation and hole in the interface.(3)Mechanical properties analysis of bending zone of copper-steel laminated plate.After laser bending of copper-steel laminated plate,the overall strength of the bending zone is enhanced.The hardness of copper layer decreases slightly after laser loading,and the strength of bending zone is mainly determined by carbon steel layer.The strength enhancement of carbon steel layer is characterized by fine grain strengthening.The variation of bending zone strength with laser parameters is systematically studied.Compared with the substrate,the tensile fracture is characterized by fine equiaxed dimple and deep dimple,which is normal stress tensile fracture.Laser bending of cold rolled copper-steel laminated plate significantly improves the mechanical properties of the bending zone.(4)Study on the application of large angle and high efficiency bending and arc forming of copper-steel laminates.The optimum processing parameters of laser bending were obtained by orthogonal experiment.Based on the total scanning times of 60 times,the bending angle of laminated plate was increased by 39.3% by means of multi-channel spot overlapping scanning strategy.When bending the arc surface,the distance between scanning lines and the diameter of spot d must satisfy a certain relationship;when the number of scanning is constant,the radius of arc in bending area increases with the increase of the distance between scanning lines;when the distance between scanning lines is uniform,the radius of arc in bending area decreases with the increase of scanning times of each scanning line.In this paper,the laser bending forming and material properties of copper-steel laminated plate are studied experimentally,which can provide theoretical data and material parameters for laser coordinated bending precision forming and numerical simulation of copper-steel laminated plate.