Study On The Titanium/steel Bimetallic Tube Diffusion Bonded Under Inner Pressure

Titanium has many excellent properties, especially the corrosion resistance. It can beused in many media. It is widely used in petroleum chemical industry, ship, energy and otherindustries. It is limited to use because the price is expensive. With titanium and steelcombination to use, it can give full play to the advantages of both performance. It has a broadprospect.The experiment use titanium tube, pure copper foil,20steel tube as test materials and thetitanium/steel double metal complex pipe was carried out by a drawn and internal pressurediffused method. The interface microstructure, fractured surface and components wereinvestigated with optical microscope, scanning electron microscope, EDS, EPMA and XRDThe bonding strength of the interface was tested by microhardness and shear test, theinfluences of process parameters, such as heating temperature and holding time, onmicrostructure, element and strength of interface have been analyzed.The results show that titanium/copper/steel interface has a good combination by a drawnand internal pressure diffused process, the interface microstructure has change obviously afterdiffusion, At850°C titanium/copper diffusion layer was appeared in the interface, thethickness of diffused layer was increased with the extension of time. Above950°C due to thespread of copper and eutectic reaction, in titanium side appeared α+β and β-Ti organization,and eutectic organization was formed in the interlayer.Interface component analysis shows that the elements interdiffusion was foundedbetween the titanium/copper interface, the different Ti-Cu intermetallic is formed in theinterface due to the diffusion. At850°C, the iron and carbon can not diffuse to the titaniumside by the interlayer.Hardness test show that the hardness of interface and interlayer was increased, becausethe elements interdiffusion and intermetallic compound, hardness value is higher than thehardness of matrix.The shear tests show that the shear strength of titanium/steel interface increases at firstand then decreases with increasing of diffusion temperature. At950°C, the maximum shearstrength can reach310MPa.