Research On Process,Microstructure And Properties Of TA2 Pure Titanium/Vessel Steel Clad Plate By Vacuum Hot-Rolling

Titanium has many excellent properties such as light weight,high heat resistance and corrosion resistance,and is an ideal material for petroleum and chemical industry.Titanium clad steel plate combines the excellent corrosion resistance of the titanium with the excellent mechanical properties and low cost of the base steel.Titanium clad steel plate is mainly manufactured by explosive welding which has the problems of low efficiency,heavy pollution and unstable performance.Vacuum rolling cladding(VRC)technology can manufacture high performance titanium clad steel plate,which has the advantages of simple process,high efficiency and environmental protection.In this paper,the vacuum hot rolling process for production of titanium vessel steel clad plate was studied(the substrate is made of two vessel steels with different alloy compositions:12Cr2Mo1R,14Cr1MoR),mainly including the effects of heating temperature,post-rolling cooling method,interlayer on the microstructure and properties of the titanium clad steel plate.The main conclusions are following:(1)The effects of heating temperature and post-rolling cooling method on the microstructure and properties of TA2 pure titanium/12Cr2Mo1R steel clad plate were studied.The elemental diffusion at the interface mainly occurs in heating and post-rolling cooling stages.Due to the large concentration grandient between Ti,Fe,C and Cr elements on two sides of titanium and steel,these elements easily diffuse at the interface to form the intermetallic compounds of TiFe?CrTi4?TiC?C2MoTi,and the preferentially generated TiC can slow the diffusion of Fe and Cr elements.With the increase of heating temperature,the more intensely diffusion of elements is,the more intermetallic compounds are formed at the interface,and the worse of the interfacial bonding property is.At 850?,there are few kinds of products at the interface,and the shear strength of the clad plate is highest(189MPa).With the high cooling rate,the interface existence large residual stress,the interface strength is low.If the cooling rate is too slow,the intermetallic compound is thick and complex,and the interface strength is low.Under moderately cold air cooling conditions,the interface strength is the highest,reaching 195 MPa.However,the interface strength under different conditions did not reach the 196 MPa specified by the GB/T 8547-2006 standard.(2)Aiming at the problem that the interface strength of TA2/12Cr2Mo1R steel clad plate is not high,the method of adding Nb and Ni interlayer to the interface is used to improve the interface performance.With the addition of Nb and Ni interlayer,the diffusion of Ti,Fe,C and Cr elements at the interface can be effectively prevented,and the Ti-Nb interface does not form any intermetallic compound,FeNb?Fe2Nb were formed at the Fe-Nb interface,and the interface products are less.The fracture position of interface is Ti-Nb interface,The ?-Ti formed at the interface has higher strength and toughness than the intermetallic compound,and the strength of the clad plate is higher,reaching 294 MPa.No intermetallic compound were formed at the Fe-Ni interface.At the Ti-Ni interface,three intermetallic compound of Ti2Ni,TiNi and TiNi3 were formed,so fracture occurred at Ti-Ni interface,the shear strength of clad plate is low,only 122 MPa.(3)The effects of heating temperature and cooling mode after rolling on the microstructure and properties of TA2 pure titanium/14Cr1MoR steel clad plate were studied.The strength of the clad plate at 800?,850? and 900? meets the requirements of the national standard,and the shear strength of the clad plate is highest at 850?,reaching 228 MPa.With the increase of temperature,the contents of Ti and C at the interface increase,When the temperature reaches 900?,the content of Cr element at the interface increases,and CrTi4 is formed,the obstruction of TiC on interface diffusion was slowed down,and the strength is low.The strength of the clad plate under the three cooling modes of water,air and slow meets the requirements of the GB/T 8547-2006 standard.Under water-cooled conditions,the shear strength is 213 MPa,and the shear strength is 221 MPa under slow cooling conditions.Under the medium cooling rate of air cooling,the interface strength is highest,reaching 228 MPa.