Microstructure and Mechanical Properties in Weld Heat Affected Zone of Titanium Alloy(Materials, Metallurgy & Weldability)
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Microstructure of weld heat affected zone of Ti-6Al-4V alloy was investigated by means of transmission electron microscopy and relation between microstructure and mechanical property, fracture toughness and delayed cracking characteristics were discussed. The mill annealed specimen and the specimen heat-treated at 973K were consisting of α+β microstructures. The β phase increased with increasing heat treatment temperature. However, the mechanical property and fracture toughness were hardly changed. The crack growth rate in water increased with increasing heat treatment temperature. For the specimen heat-treated at 1073K to 1223K, the microstructure was α+α' microstructure, α' phase increased with increasing heat treatment temperature. K_<IC> increased from 40MPa√m to 67MPa√m with increasing heat treatment temperature. The crack growth rate in water of delayed cracking decreased with increasing heat treatment temperature. For the specimen heat-treated at 1273K to 1473K, the microstructure was α' phase. The tensile strengths in both specimen were 1100MPa to 1200MPa and is higher than that of the mill annealed specimen. The crack growth rate of the delayed cracking in water was very slow, because of the α' microstructure.
- Transactions of JWRI
Transactions of JWRI 17(2), 393-398, 1988-12