INTERPHASE STRESS CORROSION CRACKING OF ALLOY Ti－24Al－11Nb IN METHANOL SOLUTION

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INTERPHASE STRESS CORROSION CRACKING OF ALLOY Ti-24Al-11Nb IN METHANOL SOLUTION

For alloy Ti-24Al-11Nb,stress corrosion cracking(SCC) in methanol solution and hydrogen induced cracking(HIC) during dynamic charging at room temperature have been studied.Experiment has shown that the normalised threshold stress intensities of SCC failure for various microstructures are KISCC/KC =0.53 0.69 and the threshold value for SCC arresting KISCC/ KIC=0.61-0.79.The threshold values of HIC during dynamic charging are close to that of SCC,but da/dt or fracture time of HIC is one to three orders of magnitude smaller or longer than that of SCC,respectively.The.fracture surface for HIC is also different from that for SCC.For the Ti-24Al-Nb alloy-methanol systein,a kind of inierphase SCC has been found For the microstructures resulting from furnace cooling,SCC initiated and propagated preferentially along theα2/βinterphase boundaries,displaying the microstructure on the fracture surface of SCC.However,there is no interphase SCC for the microstructure resulting from air cooling.