| Titanium alloy has a high specific strength,good corrosion resistance and excellent mechanical properties at high temperature,which are widely used in aerospace,military and other special and important industrial fields.But the processing of Titanium alloy is poor and the price is high,it’s important to find a reliable connection method for titanium alloys.Ti-6Al-4V is the most widely used in Titanium alloy.Because of a series excellent performance of stainless steel,it is widely applied as a common material for industry and life,and the cost is relatively low.However,the corrosion resistance of steel is relatively poor,and have a high density.Therefore,in order to give full play to their advantages,steel and titanium need to be connected in some cases.But the joint between the titanium alloy and steel is easy to form intermetallic compound(Ti2Fe,TiFe,TiFe2)when they are welded,the stress of the joint is large after welding,that’s caused the performance of joint decline.It’s of great significance to explore more scientific and efficient TC4 and stainless steel welding methods and welding process for obtain a better performance of the brazed joints.The main welding method for titanium and stainless steel is vacuum brazing.Vacuum brazing with low welding temperature and brazing samples are not susceptible to impurity gas pollution,welding deformation and low residual stress and so on.Amorphous brazing filler as a new type of brazing filler has a series of advantages including low melting point,good welding performance and convenient welding techniqueis,so amorphous brazing filler metal instead of the traditional brazing filler was choosed for vacuum brazing,among which Titanium-based amorphous brazing filler as a important amorphous brazing filler for vacuum brazing TC4 Titanium has unique advantages such as low cost and that it’s easy to mutual diffusion with base metal.This experiment we take traditional titanium-based amorphous brazing filler such as Ti37.5Zr37.5Ni10Cu15 to braze TC4 and 304 SS.In addition,in order to reduce the melting point of brazing filler,improve its solderability and ensure the mechanical properties of brazed joints between TC4 and TC4,a certain amount of Sn element was added to prepare new titanium-based amorphous brazing filler metal,such as Ti33.75Zr33.75Ni10Cu15Sn7.5 and Ti33.75Zr33.75Ni10Cu15Sn10..The three kinds of brazing filler metals are all amorphous confirmed by XRD.The melting point of brazing filler metal can be obtained by DSC,and the melting point of Ti33.75Zr33.75Ni10Cu15Sn10 amorphous brazing filler is lower than that of Ti37.5Zr37.5Ni10Cu15.A number of different brazing temperature was selected for the holding time of 10 min.The brazed specimens are subjected to microstructure observation and mechanical property test.The morphology of brazing joints was observed by SEM,it was found that obvious crack are existed in brazed joints near the 304 SS base metal during brazing TC4 and 304 SS,while the joints of brazing TC4 and TC4 are uniform and dense.When the brazing temperature is 940℃,the shear strength of TC4 and 304 SS joint is 122.14 MPa using Ti37.5Zr37.5Ni10Cu15 amorphous brzing filler,area analysis and EDS line scan of joint we can inferred a small amount of intermetallic compounds such as Ti2 Fe,TiFe,TiFe2 and so on were produced in joints.The shear strength of TC4 and TC4 joints with Ti37.5Zr37.5Ni10Cu15 amorphous brazing filler is 254.65 MPa,and the hardness of brazed joint was relatively low,It was found that a significant reticular structure was exist in the joints,this structure is conducive to release the stress of brazed joints,and the brazed joints with good quality was obtained. |
PDF Full Text Request