Tantalum sheet with high melting point, high hardness, high strength, acid corrosion resistance, good extension, chemical stability, is an indispensable material in the field of high and new technology. Pure titanium also has high corrosion resistance. Therefore, pure tantalum and titanium thin plates are widely used in the chemical industry. However, welding between thin plates or tube plates is often involved in the application process. Tantalum and titanium have good weldability, but it is difficult to weld thin plate or thin plate to thin-wall tube, mainly because deformation is easy to occur in the welding process. Taking the tantalum/titanium sheet lamination and thin-wall titanium tube welding structure in a chemical enterprise as an example, the welding problem of thin-wall tube and thin-wall titanium tube and its welding deformation are analyzed in detail.

Ta/Ti plate and titanium tube welding structure. The thickness of pure Ta plate and pure Ti plate is 0.2mm and 1mm respectively, and the size of pure Ti tube is 16mmxlmm. However, the thickness difference between tantalum plate and titanium plate (or titanium tube) is large and the melting point difference is high (Ta melting point is 3020t and Ti melting point is 1670T). At the same time, the preliminary test shows that tantalum and titanium sheet welding is easily deformed. This welding structure is used in the field of chemical industry, and the corrosion resistance of the welding seam should not be lower than that of the base material, so the welding seam must be dense without cracks and pores and other defects.

(1) manual argon tungsten arc welding is used to weld the annular seam between Ta/Ti thin laminae and Ti thin-walled pipes. The selection of appropriate process parameters, tooling and protective measures can fully meet the quality requirements of the product.

(2) optimized argon arc welding process parameters: welding current 60A, arc voltage 15V, argon flow 10L/min, welding nozzle diameter 7mm, speed 0.6mm/s, crane pole diameter 2mm, protective gas flow 12L/min; The welding position is flat welding with argon shield, weld cooling device and sheet deformation prevention device.

(3) the gas tightness of the welding seam was detected by helium mass spectrometer, and the leakage rate of the annular welding seam was 5.0 x10-11pa.mvs, which indicated that the welding seam was compact and without welding defects.