Because the volume of the welded parts of carbon steel and titanium alloy is not too big, and it is a sealed weldment ring, the protective welding in the box should be used, and the brazing material used is HL313. The carbon steel grade is Q235-A, and the ring processing has a boss; the titanium alloy grade is industrial pure titanium TA2, the ring processing has a groove, and the two rings have appropriate matching requirements. Before brazing, make full preparations to remove the corner burrs and surface oxides of the parts; clean and degrease with acetone; pad two layers of 0.10mm thick foil solder next to the mixed boss to control the boss and groove Between the gaps, place the φ4mm wire solder on the boss and assemble it with a clamp.
The brazing device used is a sand-sealed argon-filled tank. The argon-filled tank is usually composed of an air inlet pipe, an air outlet pipe, and a box body. The heating furnace is a H-75 box-type electric furnace with a power of 75kW.
After putting the assembled weldment assembly into the argon-filled box, pre-fill it with argon gas for 1h in order to remove the air in the box. Put the argon-filled box into the electric furnace for heating. When the weldment reaches the brazing temperature of 800 ~ 830 ℃, keep it warm for 20 minutes. After the argon filling box is out of the furnace, the temperature is reduced to below 200 ° C to stop argon filling. Open the argon filling box and take out the weldment. Due to the sealing requirements, a leakage test of 0.05MPa ammonia is performed after welding, and the shear strength of the welded joint is 98MPa.
