Pulsed Laser Spot Welding Process And Properties Of Zr-Based Amorphous Alloys

The Zr-based amorphous alloy material has the advantages of high strength,good wear resistance,good corrosion resistance,and metallic luster.It is a kind of good raw material for mobile phone case.As a widely used precision welding method,laser welding can accurately control the welding process and is suitable for connecting small parts in electronic products.In this paper,a Zr-based amorphous alloy with a thickness of 1.5 mm was welded using a pulsed laser.Crystallization at different welding currents is summarized.The influence of process parameters on solder joints and its optimization have been studied during pulsed laser spot welding of Zr-based amorphous alloys.The welding results of Zr-based amorphous alloy under vacuum and atmospheric conditions were comparedFirst,the crystallization behavior of Zr-based amorphous alloys was explored.With different welding currents,the WFZ is in an amorphous state,and there is a partial crystallization phenomenon in the HAZ.The larger the welding current,the larger the grain size in the heat-affected zone.When the welding current is 108A,Zr₂Cu grains with a size of about 5 nm appear in the HAZ.The mechanical properties and corrosion resistance of the solder joints are improved compared with the base metal.When the current is increased to 120A,the grain size of Zr₂Cu is about 4μm,a large number of defects appear inside the grain,and the mechanical properties and corrosion resistance of the solder joint are reduced.Then,the effects of welding current,pulse width and defocus amount on the size and performance of solder joints in pulsed laser spot welding of Zr-based amorphous alloys were analyzed by Taguchi method.Mathematical model between welding parameters and solder joint quality was established and the welding parameters were optimized.It can be concluded by the signal-to-noise ratio analysis and analysis of variance results that welding current has the greatest influence on welding quality,followed by pulse width,and the influence of defocus amount on solder joint quality was the smallest.The best parameter range obtained is:welding current 100A,pulse width 5.0ms,defocus amount-1.41^-1.47mm.As the welding current and pulse width increase,the weld spot size and penetration depth increase gradually;The larger the defocus amount,the spot size first decreases and then increases,and the penetration first increases and then decreases.The maximum load of a single solder joint is related to the product of the welding current and the pulse width.As the product increases,the maximum load increases first and then decreases.Finally,a comparative analysis of the welding results under vacuum conditions and atmospheric pressure shows that the vacuum condition has a certain inhibitory effect on the pores.Under the same welding parameters,the crystallization of solder joints obtained under vacuum conditions is more severe and the crystallization position is not changed.