| Titanium has excellent corrosion-resistance,known as "ocean metal".China’s offshore is a continental shelf,with the characteristics of high sediment,erosion and corrosion of marine engineering equipment is very serious.Compared with α-Ti alloy,the high strength TC4 titanium alloy with α and β dual phase has excellent erosion corrosion resistance.However,the high cost of titanium greatly limits its application.Compared with titanium alloy,EH690 high strength marine steel has lower cost and higher strength and toughness.Therefore,TC4 titanium alloy and EH690 high strength marine steel can be clad,and the obtained titanium/steel clad plate has the combination of strong corrosion resistance of titanium and the high strength and toughness and low cost of steel,which has a broad application prospect in the field of corrosion protection of marine engineering.At present,the explosive cladding and rolling cladding methods are widely used to fabricate clad plate in China.Explosive cladding has serious environmental pollution,low production efficiency and unstable interface quality,etc.,and has been gradually eliminated in foreign countries.The common rolling clad interface is easy to be oxidized,which affects the bonding strength of the interface.In recent years,vacuum rolling cladding technology has been developed based on the traditional hot rolling cladding technology and vacuum electron beam welding technology,which is advanced technology for the production of clad plates.In this study,TC4 titanium alloy/EH690 marine steel clad plate was prepared by vacuum rolling technology,and the formation mechanism and mechanical properties of the clad interface were studied.The main work and research results are as follows:(1)The effect of rolling temperature on microstructure and mechanical properties of titanium alloy/marine steel clad interface was studied.The clad interface is composed of TiC and a small amount of TiFe2 compounds.The number of TiFe2 compounds increases with the increase of heating temperature,and the bonding strength of the interface decreases significantly.At the heating temperature of 865℃,the bonding strength of the interface is the highest,reaching 155 MPa.(2)The on-line quenching and tempering and off-line quenching and tempering processes of titanium alloy/offshore steel clad plates were studied.Compared with the off-line quenching and tempering,the interfacial element diffusion is significantly inhibited,the interfacial brittle products are less,and the interfacial bonding strength increases from 79 MPa to 155 MPa.(3)The effect of the interlayer on the microstructure and mechanical properties of the clad interface was studied.The interlayer of H62 brass does not prevent the diffusion of titanium,there are a lot of TiC and Ti-Cu compounds at the interface,and the interfacial shear strength is only 103 MPa.The nickel interlayer causes a formation of brittle layer of TiNi2 compound with shear strength of 110 MPa.After the insertion of Nb interlayer,the Nb-Ti solid solution and TiC phase are formed at the interface,and no brittle Ti-Fe phase is formed,where the shear strength reaches 277 MPa.The addition of vanadium layer significantly inhibits the diffusion of elements on both sides,and only produces a small amount of TiC layer at the interface with the interfacial strength being as high as 313 MPa.(4)The preparation process of TC4 titanium alloy/EH690 marine steel clad plate was developed.Titanium alloy and marine steel are treated with water sand belt machine to obtain clean surface.The titanium/steel clad slab was packed by vacuum electron beam under the condition of 85 kV acceleration voltage and 45 mA beam current.The hot rolling was carried out at 865℃ and the reduction rate was 80%,The interface shear strength of the clad plate reaches 313 MPa. |
PDF Full Text Request