Study On Dynamic Compression Mechanical Behavior Of Additive Manufacturing TC4/CP-Ti Heterogeneous Material

In recent years,heterogeneous lamella structured titanium alloy have attracted much attention due to their superior protective efficiency under high velocity impact.However,the deformation failure mechanism under high strain rate and the influence mechanism of interface on dynamic mechanical behavior have not been revealed,which cannot provide reference for the design of heterostructure materials.In this paper,the effect of strain rate on the deformation failure behavior of TC4/CP-Ti double-layer heterogeneous material fabricated by additive manufacturing is studied,and the influence of the orientation relationship between the heterogeneous interface and the loading direction(vertical,parallel,45°)and heat treatment on its dynamic deformation and adiabatic shear failure behavior is studied.Firstly,the quasi-static(0.001 s-1 and dynamic(3000 s-1)compression tests were carried out on the as-deposited heterostructure materials with a vertical relationship between the loading direction and the interface to study their static and dynamic compression mechanical behaviors.The results show that the heterostructure material has obvious strain rate strengthening effect,and the strain rate will affect the deformation failure behavior of the heterostructure sample.Under the condition of quasi-static compression,shear failure occurs along the direction of maximum shear stress along the outer edge of TC4 matrix end face.Under the condition of dynamic compression,the radial deformation of CP-Ti matrix with lower strength is much larger than that of TC4 matrix on the other side of the interface,while the TC4 matrix far away from the interface is difficult to coordinate deformation in a very short time.Finally,a large stress concentration is generated in the area near the interface of TC4 matrix,and adiabatic shear bands(ASB)are formed.Secondly,the as-deposited heterostructure material with different loading directions and interfaces were subjected to dynamic compression loading,and the adiabatic shear sensitivity was characterized by the energy absorbed when the adiabatic shear failure occurred.The results show that the ability of the heterostructure material with vertical orientation to resist adiabatic shear failure is improved compared with the homogeneous matrix,and its adiabatic shear sensitivity is the lowest.The hetero-deformation induced effect of TC4 matrix on the interface side in the direction perpendicular to the interface can effectively inhibit the expansion of ASB and deflect the expansion direction of ASB.In the material with parallel orientation relationship,the heterogeneous interface region cannot produce abnormal deformation induction effect,and the ability to resist adiabatic shear is less than the former.For the heterostructure material with 45° orientation relationship,adiabatic shear occurs along the interface direction in the area near the interface of the CP-Ti matrix.The direction of action of the hetero-deformation induced effect generated in the interface area is perpendicular to the expansion direction of the ASB,which fails to inhibit the expansion of the ASB.Finally,the effect of heat treatment on the dynamic deformation and failure behavior of heterogeneous materials was studied.The results show that after heat treatment at 930℃/4 h/FC and 1030℃/4 h/FC,the energy absorbed by the 45° interface heterogeneous material during dynamic deformation failure is 16%and 40%higher than that of the deposited state,respectively,while the energy absorbed by the vertical and parallel interface heterogeneous materials is reduced.After heat treatment at 1030℃/4 h/FC,the adiabatic shear failure mode of the heterogeneous material with vertical interface changes,and the initiation position of the adiabatic shear band changes from the vicinity of the interface to the outer edge of the TC4 matrix end face.