Study On Cladding Of Inconel625 On The Surface Of X 65 Steel By Cold Metal Transfer Welding

Inconel625 alloy,capable of resisting against corrosion,could perform well in high temperature environment.Cladding Inconel 625 on the inner surface of the steel tube is a method of getting economical clad pipe with both high hardness and corrosion resistance ability.With the characteristics of waveform control and small current short circuit transition,the CMT welding can reduce the heat input and effectively improve the dilution rate in the surfacing problem.Therefore,the studying on the welding process of Inconel625 by CMT has theoretical value and practical significance for applying CMT welding to Ni-based alloy surfacing.First of all,this paper analyzes the CMT welding process and waveform.Combined with the characteristic of larger viscosity coefficient of Inconel625,the welding procedure was adjusted to make a smooth transition of molten droplets.And the effect of wire feed speed on the stability of CMT welding was studied.It was found that the stability of CMT welding decreased with increasing wire feeding speed.When the wire feed speed is over 9m/min,the mixed transition forms of short circuit transition and droplet transition inclusion begin to appear.Secondly,single-factor experiment was conducted to find out the parameters of welding and their reasonable variable interval.The effects of CMT welding parameters on the weld formation were studied by full-factor experiments.The linear regression equation of dilution rate was established by taking feed rate(X1),welding speed(X2)and wire inclination(X3)as factors : Y =-9.98 + 2.59 X1-0.0497 X2-0.0341 X3.And then the effect of heat input on the microstructure and properties of CMT overlaying layer was summarized by controlling the variation.At last,the welding parameters were selected to conduct multi-pass welding test,considering dilution ratio,weld width and wetting angle.The results show that the surfacing is the best when multi-channel surfacing is conducted with 5mm pitch.The electrochemical test shows that the corrosion resistance increases with the thickness of the overlay,but the difference of the corrosion resistance everywhere is not big.