Effect Of Cold Rolling And Annealing Process On Interface And Properties Of Cast-Rolling Ti/Al Composite Plate

In this paper,the Ti/Al composite plate is prepared by cast-rolling method and subjected to cold rolling and annealing process.The comprehensive performance of the cast-rolling Ti/Al composite plate is obtained through the relevant research on the casting rolling state,cold rolling state and annealed state of the composite plate prepared by cast-rolling method.The morphology and phase of the interface layer and the peeling surface are observed and tested by metallographic microscope,SEM,TEM and XRD.The peel strength and mechanical properties are tested through the peeling testing machine,tensile testing machine and micro-hardness tester.In addition,the comprehensive properties of the composite plate prepared by cast-rolling method are obtained by comprehensive analysis.The experimental results show that the interface layer of Ti/Al composite plate prepared by cast-rolling method is flat and the metallurgical bonding of the interface layer is good.The thickness of interface layer of Ti/Al composite plate of 6.5 mm thick is about 1?m.And the mismatch degree between the two kinds of atoms of Ti and Al in the interface which are semi-coherent combination is 0.15.The grain size of the base metal is equiaxial.The Ti Al3 is the only intermetallic compound on the interface layer,and the TiAl₃ is in the form of tetragonal structure and cubic structure,but the amount of TiAl₃ is very small,which is not enough to affect the comprehensive performance of the Ti/Al composite plate prepared by cast-rolling method;the peel strength of cast-rolling Ti/Al composite plate of 6.5 mm thick is 31 N/mm and the bonding strength is high,the tensile strength is 172 MPa which is larger than its theoretical calculation of 136 MPa,the elongation is 34%.The Ti/Al composite plate of thickness of 5 mm and 4 mm,3 mm are obtained by cold rolling processes of 23% and 38%,53% on that of 6.5 mm thick.The interface layer is gradually destroyed with the increase of cold rolling reduction rate,when the rate of cold rolling is 53%,the interface layer has relatively more fracture,and the two base metals of Ti and Al are direct contact in some areas.With the increase of the cold rolling reduction rate,the combination of the Ti/Al composite plate changes from the metallurgical combination into the metallurgical bonding and mechanical engagement,and finally the mechanical engagement.The peel strength of Ti/Al composite plate decreases rapidly after cold rolling process,when the cold reduction ratio is 38%,the tensile strength of Ti/Al composite plate is 241 MPa,and the elongation is 13%,as well,the comprehensive performance is the best.After heat treatment of different annealing processes on the cast-rolling Ti/Al composite plate of thickness of 5 mm,the thickness of metallurgical bonding layer increases gradually.And the thickness of the intermetallic layer is 1.5 ?m at 450 ?×3 h,with the slight increase of the annealing temperature or the holding time,the increase of the thickness of the interfacial layer of the composite plate is very small.In the annealing processes,the peel strength of the Ti/Al composite plate increases from the 28 N/mm of casting rolling state to 33 N/mm at 450 ?×3 h.The peel strength decreases slightly with the increases of annealing temperature or prolonging holding time.At 450 ?×3 h,the tensile strength of the composite plate decreases from 147 MPa to 103 MPa and the elongation increases from 33% to 53%,as well,the performance is the best.