Study On Microstructure And Properties Of A1 1060 And SiCp/Al Composites Fabricated By Resistance Seam Additive Manufacturing

Resistance seam welding is a traditional welding technique.In this paper,the resistance seam welding technique is used to realize additive manufacturing by surfacing prefabricated powder,and Al 1060 and SiCp/Al composites are successfully prepared.Firstly,the influence of the parameters of resistance seam welding on the thickness,porosity and hardness of single-layer Al 1060 was studied to obtain the optimal technological parameters,which were used to prepare Al 1060 bulk.Based on the parameters,the welding speed was changed and SiCp/Al composites were prepared at different welding speeds.The effects of welding current,welding velocity and electrode pressure on the thickness,porosity and hardness of single-layer Al 1060 were analyzed by orthogonal test.The results show that the influence of thickness is as follows:welding current>Welding speed>Electrode pressure;The influence on porosity is as follows:welding current>Electrode pressure>Welding speed;The influence on hardness is:welding speed>Electrode pressure>welding current.The optimal welding current parameters were obtained by range analysis:welding current is 5 k A,welding speed is 24 cm/min,and electrode pressure is 0.4 MPa.According to the theoretical calculation under ideal conditions,the instantaneous increase temperature of Al 1060 powder particles during the welding process is more than 2000 K.The internal structure of the Al 1060 powder particles is dense,the grain size is 6-8μm,and the grain size gradually decreases along the accumulation direction.At the same time,a small amount of Al₈Fe₅ phase was formed at the grain boundary.The porosity of the sample is only 0.017%and the density is 2.67 g/cm³.The mechanical properties of the upper part of the sample are the best,the average nanohardness and average elastic modulus are 392.5MPa and 88.6MPa,tensile strength is 63.5MPa.SiCp/Al composites were successfully prepared by resistance seam additive manufacture.The effects of different welding speeds on microstructure,hardness and tensile strength of the specimens were studied.The results show that:the forming mechanism of SiCp/Al composites and the formation mechanism of porosity defects in the sample was revealed by the characterization of the internal microstructure of the samples.The porosity is mainly distributed between Si C and Si C particles and between Al matrix and Si C particles.The results show that there is no interfacial reaction between Al and Si C particles during the process of resistance seam additive manufacture.The porosity increases with the increase in welding speed,and the mechanical properties decrease with the increase in welding speed.The lowest porosity is 1.672%at the welding speed is 24 cm/min.The average hardness,tensile strength and elongation are 47.32 HV_0.1,52.16 MPa and 2.2%,respectively.The sample cracks along the interlayer bonding interface and the bonding interface between Al matrix and Si C particles,and the fracture mode is a ductile fracture.