Microstructure And Mechanical Property Of Vacuum Manufacturing Billet Hot-Rolled Titanium Clad Steel Plate

Titanium has excellent corrosion resistance,but also costs high.Q345R steel is a common structural material with good comprehensive performance and costs lower than titanium.Titanium clad steel plate combines advantages of the two kinds of materials,which can be used in many situations that demand titanium alloy.And titanium clad steel plate has better strength and plasticity.The most important is that titanium clad steel plate costs much lower than titanium alloy.With the fast improvement of our titanium clad steel plate,titanium clad steel plate will be used in many ways and be more important in compound material.In our country,titanium clad stainless steel plate is mainly manufactured by explosive welding which has low efficiency and much pollution.While vacuum hot rolling is an excellent method instead of explosive welding.And vacuum manufacturing billet hot-rolled method has high production efficiency,little environmental pollution,high interfacial bonding strength.In the world it has become the main production method of titanium clad steel plate.Therefore,our country must research and perfect our own intellectual property rights of the vacuum manufacturing billet hot-rolled titanium clad steel plate.In this paper,the vacuum hot rolling process for production of titanium clad steel plate was studied.We choose three schemes to study the clad plates.The clad plates bonded without interlayer,with Fe interlayer and with Ni interlayer were selected to research the impact of rolling temperature and different surface treatment on microstructure and mechanical property.Interfacial microstructure and properties by titanium in the lateral coating were studied.The main conclusions are as follows:(1)The titanium clad plates bonded with different treatment on surface had relatively large surface microstructure difference.No obvious bump is on the surface treating by water belt machine and the surface has good flatness.The average shear strength can reach 239MPa at 850℃.(2)The layer of TiC can reduce the formation of brittle metal compounds in interface and Ti-Fe brittle compound.So the continuous uniform thickness layer of TiC can improve the bond strength of the interface.The β-Ti has good toughness and β-Ti is the ideal interface.The β-Ti and TiC increases with the increasing of rolling temperature.But the metal oxide at the interface increases by increasing temperature,and the interface strength is also affected.The bonding strength of the interface was the highest when the rolling temperature was 900℃,the average shear strength was 268MPa.Fracture of titanium clad steel plate was almost all brittle fracture.The strength of shear became higher with the more obvious tearing fracture morphology.(3)The mechanical properties of the vacuum hot rolling with Fe interlayer were not significantly improved comparing to the explosive rolling,and the bond strength of the interface was slightly increased.The addition of Fe interlayer can effectively inhibit the diffusion of C element,and fracture is brittle fracture and ductile fracture.Ti and Ni generated brittle compound by vacuum composite rolling adding Ni interlayer.The formation of Ti and Ni brittle intermetallic compound greatly reduced the interface bonding strength.(4)Titanium in the outer coating of titanium steel clad plate had little strength.The strength of titanium steel clad plate decreased significantly with increasing temperature.This is due to the poor sealing of interface.Oxide interface increased with the increasing of temperature and affected interface bonding strength.Titanium welding appeared in the inner part of the porosity,undercut and other issues resulted in poor interface sealing,which greatly affected the bonding strength.To prevent weld gas hole and bite edge,we need to reduce welding speed,control welding current,and make sure that welding heat input was not be too large.