Study On Four-point Bending Behavior Of Explosive Welding Interface Of TA2 Titanium/Q345 Steel Plate

TA2/Q345 composite board has both corrosion resistance of composite titanium and high strength of substrate steel.It has broad application prospects in aerospace,oil and gas,military,marine and nuclear industries.The interface as an important part to connect the composite material with substrate,which determines the overall service behavior of the material to a large extent.Until now,the researches on the explosive welding interface have more focused on waveform control and mechanical property test.It is almost blank on awareness of interface failure behavior and assessment of structure performance.This paper based on XRD,EDS and nanoindentation test,elemental analysis and physical property test were carried out on TA2/Q345 explosive composite samples.Then,pre-crack four-point bending test was set up for samples with different widths,combined with experimental observation and development curve.The failure process of the sample is described,and the maximum cracking stress and the interface strain energy release rate of the sample are calculated according to the material mechanics and fracture mechanics theory.The strength of the sample is quantitatively expressed and the numerical basis is provided for the subsequent finite element model.The fracture surface morphology of the crack is observed and analyzed,and the characteristics of the interface crack propagation path are explored.Finally,the ductile damage model and the cohesive model are used to simulate the cracking of the composite material and interface debond,finally compared with the experimental results and maked the parametric analysis for finite element model.In this paper,the failure behavior of the pre-cracked explosive welding specimen under four-point bending is systematically analyzed.The whole failure process of the specimen is systematically analyzed and finite element numerical simulation is carried out.The main research conclusions are as follows:（1）There are intermetallic compounds such as TiFe and TiFe₂ at the interface of titanium/steel explosive welding materials.These mixed phases may have influence on the bonding properties of the interface,and the elastic modulus of the materials near the explosive welding interface.The amount of value has increased to a certain extent compared with the normal state,which is related to the crystal change during the explosion welding;（2）The pre-crack four-point bending test results indicate that the critical loads of the interface failure are gradually increased as the widths of sample increase.The maximum fracture stress of the composite TA2 is approximately equal to its maximum tensile strength of 550 MPa,and the critical strain energy release rate at the interface cracking is about 5.85 N/mm.The metal melting zone causes brittle fracture and accelerates the failure process of the interface;（3）Numerical simulation results show that the ductile damage model combines with and the cohesive model can be well used to simulate the entire failure process of the explosive welding specimen,and reveal the stress field,displacement field and equivalent plastic deformation field and so on,an increase in the fracture energy parameter will increases in the steady state load value.