A Study On Stress Corrosion Cracking Of Titanium And Titanium Alloy

Purpose: To test and to evaluate the stress corrosion cracking behavior of dental titanium and titanium alloy with the help of the theory and methods of fracture mechanics. Using metallurgical microscope and SEM to analyze the fracture surface and to approach the mechanisms of fracture. Establishing a evaluating system of the stress corrosion cracking behavior of dental titanium and titanium alloy. Methods: Using pre-cracking specimens and constant displacement method to study the stress corrosion cracking behavior of dental titanium and titanium alloy in artificial saliva with and without fluoride. Using crack termination method to measure critical stress field intensity factors K_ISCC establishing the relationship between stress field intensity factors K_I and velocity of crack propagation da/dt, and drawing curve of it. Using mathematical method to estimate the maximum deficiency dimension within permission of dental prosthesis. Analyzing the fracture surface by fractal dimension method and metallurgical microscope and SEM, describing the fracture characteristics and approaching the mechanisms of fracture. Results: 1. The critical stress field intensity factor K_ISCC of Ti-6Al-4Vin artificial saliva is 52.720 MPa ·m^1/2, the K_ISCC of Ti-6Al-4V inartificial saliva with fluoride is 50.053 MPa · m^1/2 ,which are noteffected by the initial stress field intensity factor. Pure titanium do not express any crack propagation in both circumstance, even being effected by a very high initial stress field intensity factor. 2.The...