Microstructure Dependent Fatigue Cracking Resistance of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si Alloy

Z.M.Song 1),L.M.Lei 2,3),B.Zhang 4),X.Huang 3) and G.P.Zhang 1) 1) Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China 2) AVIC Commercial Aircraft Engine Co.,Ltd.,Shanghai 200241,China 3) Titanium Alloys Laboratory,Beijing Institute of Aeronautical Materials,Beijing 100095,China 4) Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education,School of Materials and Metallurgy,Northeastern University,Shenyang 110819,China

摘 要：Fatigue cracking behavior from a notch was investigated at room temperature for Ti-6.5Al-3.5Mo-1.5Zr-0.3Si（TC11） alloys with four different microstructures obtained at different cooling rates from the β transus temperature.It was found that the alloy with lamellar structures consisting of α/β lamellae or acicular α’ martensite laths had a higher fatigue crack initiation threshold from the notch,while the bimodal structure with coarse α grain had a lower fatigue cracking resistance.The alloy with α/β lamellar structure showed a higher fatigue crack growth resistance.The length scales of the microstructures were characterized to correlate with fatigue cracking behavior.Fatigue cracking mechanism related to microstructures was discussed.

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