Research On Vacuum Furnace Brazing Of Ta1 Tantalum And S30408 Stainless Steel Plates

Tantalum material is used to make acid evaporator and acid/acid heat exchangers in the field of chemical industry because of its excellent corrosion resistance,can't be replaced.But the tantalum is expensive.Tantalum-stainless steel composite structure can not only make full use of the performance of tantalum,but also reduce the cost of production.While it is so difficult to make the welding of tantalum and stainless steel because of the great differences of physical and chemical performance between tantalum and stainless steel as while as the easly formation of brittle intermetallic compounds Fe2 Ta,which dramaticlly weaken the joint properties.In this paper,two series filler metals Ni-Cr-Fe-Si-B and Ni-Cu-Ge-Si-B are designed and prepared and being used in the vacuum furnace brazing of Ta1 and S30408 plates.the joint microstructure and properties are Studied and the influence of filler composition on joint microstructure and properties are analysed.the mutual diffusion reaction between two parent metals controlled and the brittle intermetallic compounds inhibited by increasing the thickness of filler metals.Finally the experiment of brazing Ta1 and S30408 steel tube-plate structure was carried out using the optimized brazers.The results show that:Two series of filler metals can achieve the effective connection of Ta1 and S30408 plates,the strength of Ta1/S30408 brazing joint is higher which used Ni-Cr-Fe-Si-B filler metals.Under the condition of welding temperature 1040??holding time 1h ? vacuum degree 1×10-2Pa,Ni81.5Cr8Fe2Si5B3.5 filler metal with thickness of 0.3 mm is used in the vacuum furnace brazing of Ta1 and S30408 plates,the shear strength of joint ?=154MPa;under the condition of welding temperature 950? ? holding time 1h ? vacuum degree 1×10-2Pa,Ni52.5Cu35Ge6Si3B3.5 filler metal is used in the vacuum furnace brazing of Ta1 and S30408 plates,the shear strength of joint ?=121MPa.The latter shear strengthfails to meet the Ta1/S30408 explosion composite board standard requirements of140 Mpa.Using Ni81.5Cr8Fe2Si5B3.5 filler metal to carry out the experiment of brazing Ta1 and S30408 steel tube-plate structure,under the condition of welding temperature 1030??holding time 2h?vacuum degree 1×10-2Pa,the shear strength of tube-plate joint up to ?=169MPa,meet the explosion composite board standard requirements,but the joint has low bending performance,the Ta1 plate is delaminated at bending Angle of 20°.There is no obvious bulge or delamination on Ta1 plate in the vacuum pressure test of Ta1/S30408 tube-plate at-0.1MPa.The stability of brazing Ta1/S30408 tube-plate structural meet the engineering requirements of Ta1/S30408 composite tube-plate.