Interface Microstructure Control Of Titanium Steel Clad Plate And Its Effect On The Growth Of Fe-Ti Compound

Titanium/steel composite board is a key basic material in marine,aerospace,chemical,energy and other fields.Since titanium is an active metal,it is easy to form Fe-Ti brittle phases during the preparation of titanium/steel composites,which deteriorates the bonding strength of the composite interface.In order to avoid the formation of Fe-Ti brittle phase,the industry usually uses explosive weldding method to prepare titanium/steel composite material,which has low production efficiency and serious environmental impact.Rolling compounding method is an important method for the preparation of heterogeneous metal composite materials,and people have been trying to apply rolling compounding technology to the field of titanium/steel composite material preparation.In order to avoid the formation of Fe-Ti brittle phases at the interface during the preparation of composite materials,the composite rolling temperature must be limited to below 850°C,which not only affects the performance of the substrate,but also the ability of the rolling equipment has become a key bottleneck restricting production.In order to solve the above problems,this paper uses titanium surface modification to control the composite interface microstructure in the high temperature stage,suppress the formation of the interface Fe-Ti brittle phase,and realize the direct preparation of titanium/steel heterogeneous metal composite materials at 900?.The main research conclusions are as follows:(1)The introduction of ?-Ti stabilizing element Ga on the titanium surface can change the interface microstructure of the titanium/steel composite plate.When the titanium/steel clad plate is directly hot rolled,the ?-Ti stabilizing element Fe diffuses into the titanium surface to reduce the phase transition temperature of titanium.After rolling at 850?,the interface microstructure on the TA2 side is ?-Ti.After surface treatment of titanium with ?-Ti stabilizing element Ga,the phase transition temperature of titanium can be increased.After rolling at 950°C,the interfacial structure on the TA2 side is ?-Ti+?-Ti composite structure.(2)The ?-Ti+?-Ti composite structure can inhibit the diffusion of C atoms to the titanium side and form a uniform and continuous TiC layer at the composite interface.After rolling at 850°C,900°C and 950°C,the thickness of the TiC layer at the titanium/steel composite interface is 190 nm,180nm and 510 nm,respectively.(3)TiC and ?-Ti+?-Ti composite structure work together to inhibit the diffusion of Fe atoms from the steel side to the titanium side.Directly hot-rolled titanium/steel clad plate,after 850? hot rolling,the atomic percentage of Fe in the diffusion zone on the TA2 side is 15.49%.After Ga surface treatment,at 850?,900?,950? rolling temperature,The TiC and ?-Ti+?-Ti composite structure reduces the atomic percentage of Fe in the diffusion zone on the TA2 side to 8.46%,8.24% and 9.02%,respectively.(4)The composite structure of TiC and ?-Ti+?-Ti helps to inhibit the formation of Fe-Ti brittle phases and improve the interface shear strength of titanium/steel composite plates.After Ga surface treatment,when the rolling temperature is 850? and 900?,the interfacial shear strength of the composite plate is 225 MPa and 235 MPa,respectively,but when the rolling temperature is increased to 950?,the interfacial shear strength of the composite plate reduce to 145 MPa.(5)The rapid thickening of the TiC layer is the main reason for the decrease of the interface bonding strength.After the rolling temperature rises to 950°C,the diffusion coefficient difference between the C element on the steel side and the titanium side increases,resulting in a sharp increase in TiC,and the formation of Fe₂ Ti in TiC,resulting in a decrease in the interface bonding strength.(6)Laser surface treatment cannot effectively improve the shear strength of titanium steel composite panels.At low temperature(850°C),after using laser surface treatment,a mixed phase of TiC and Fe-Ti intermetallic compounds is still produced at the interface of the titanium-steel clad plate.The shear strengths of direct hot rolling,Ga modification,laser cleaning and laser quenching hot rolled titanium steel composite plates are 180 MPa,225MPa,175 MPa and 185 MPa,respectively.