The Microstructures and Fatigue Crack Growth Properties in Ti-6Al-4V Laser Welds
碩士 === 國立海洋大學 === 材料工程研究所 === 85 === The present work was undertaken to investigate the effects of microstructures on the mechanical properties and fatigue crack growth in Ti-6Al-4V plate and laser welds. Experimental results revealed Ti-6Al-4V alloy was heat-treated in...
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| Other Authors: | |
| Format: | Others |
| Language: | zh-TW |
| Published: |
1997
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| Online Access: | http://ndltd.ncl.edu.tw/handle/00003849064016698880 |
| Summary: | 碩士 === 國立海洋大學 === 材料工程研究所 === 85 === The present work was undertaken to investigate the effects of microstructures
on the mechanical properties and fatigue crack growth in Ti-6Al-4V plate and
laser welds. Experimental results revealed Ti-6Al-4V alloy was heat-treated in
vacuum at 950℃ for 40min and cooled subsequently by Ar quence.
The microstructures
is cosisted of refined lamellar α plus βin the base metal (BM). The results
also indicates the microstructure of various aged specimens is almost similar.
The presence of martensite in the narrow fusion zone (FZ),
results in the tensile
fracture of laser-welded specimens in the BM. The decomposition
of martensite can
account for the slightly hardening of laser welds after
postweld heat treatments.
The variation in tensile properties is minor for variously aged specimens.
In addition, the welds aged at various temperatures show minor
difference in tensile
properties. The fatigue crack growth rates decreased at low ΔK range can be
attributed to the presence of residual compressive stress in
laser welds. The results
reveal the FZ retards the crack growth most among various regions in a weld.
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