Study On Fatigue And Fracture Performance Of TC11Titanium Alloy Electron Beam Welded Joints

Materials and processes are very demanding requirements during the manufacturingof aero engine because of the harsh working environment. How to evaluate theperformance of the materials is the major bottlenecks encountered during the designand manufacturing process of the advanced aero engines, and, this situation hasseriously affected application of the new materials, technology and structures in theaero engine.The results showed that the TC11weld exhibited a pin shape, and the columnargrains in the fusion zone contained needle-like martensite phase. The micro-hardnessof the welds exhibited a ladder distribution. The average value of the hardness of theweld was430HV, which was significanly larger than the base materials (360HV).From room-temperature to500℃, the strength of the weld and the base material werethe same. The weld exhibited a decent compatibility. The tensile strengths of the weldand base material both decreased as the temperature increased.Both the HCF and LCF properties of the TC11weld reached those of the basematerial. When tesing the LCF property of different zones of the welds, the fatigueproperty of the weld was higher than the base material. The fatigue results on thenotched samples have shown that the faigue scatter is the same as that of the basematerial. The double-notched samples were more prone to have cracks, causing alower fatigue life than the single-notched samples. When the welding defects wereminimized, the predicted fatigue life of the TC11weld has a larger safty margin usingthe same model as the base material. However, if the strain concentrated in the fusionzone and was plastic, a lower safty margin was obtained using the same predictingmodel.The EB welds of TC11exhibited a cleavage fracture and the material is defectsensitive. The FCG rate of the weld is higher than that of the base material. The weldis crack sensitive. In addition, the structure is also crack sensitive because the internalstress and the stress intensity factor of the structure are both high. Only shallowsurface cracks can pass the safety evaluation.