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ML00005 - Apr.2017

Environmental Hydrogen Damage in Ti Pipe

Internal aspect of the 8" diameter pipe that suffered localized thinning and leakage. The vertical weld is the pipe seam and the horizontal weld is the circunferential butt weld.

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Internal aspect of the 8" diameter that suffered localized and . The vertical weld is the and the horizontal weld is the circunferential butt weld.
M

Material

Unalloyed Titanium
  • UNS R50400
  • ASTM B 862 grade 2
Ds

Description

The had suffered associated to localized of the welded regions (both and circunferential welds). The thinning is not related to but to brittle detachment of a hydride layer at the . The localized occurred because the in the welded region favoured easy detachment (by ). The base material also presented a hydride layer but it did not detached in the same way as the .

C

Chemistry (% in weight)

Base metal

99.5Ti.

Weld Metal

98.9Ti.

Associated Images
Internal aspect of the 8" diameter pipe that suffered localized thinning and leakage. The vertical weld is the pipe seam and the horizontal weld is the circunferential butt weld.
564
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Aspect Before AnalysisDf - Localized Thinning
External aspect of the 8" diameter pipe that suffered localized thinning and leakage associated to the welded regions. The vertical weld is the pipe seam and the horizontal weld is the circunferential butt weld.
142
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Aspect Before AnalysisDf - Welded Joint
Aspect of the internal surface of the pipe at the welded region, showing the interface of the thinning area in the weld and the pipe base metal.
128
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Surface Aspect by SEMDf - Localized Thinning
Region of the localized thinning at the weld metal, in a metallographic section, as polished. In the base metal the hydride layer is continuous and no thinning is evident (left side of the figure) and in the weld metal it is detached and cracked (right side of the figure).
107
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Micrography by SEMDf - Localized Thinning
The microstructure of the pipe base metal, in the center of the thickness, is granular alpha.
102
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Granular structure
The pipe base metal, at the internal surface, presents a hydride layer showing that the environment is absorbing hydrogen. Although there are microcracks in this layer it did not detach in the base metal.
102
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Hydride Formation
The microstructure of the pipe seam weld metal, in the center of the thickness, presents a coarse prior beta grain size.
85
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Columnar Grains
The pipe internal suface, at the welded region, presents no hydride layer (because it has detached) as well as the material itself is suffering brittle detachment.
71
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Localized Thinning
Detail, as polished, of brittle cracks in the weld metal, from the internal side of the pipe.
67
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Micrography by OMDf - Brittle Cracks
Seam weld of the pipe showing the localized thinning in the weld metal, caused by the detachment of the hydride layer and brittle behaviour of the coarse weld metal structure.
64
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Kroll Etched Micrography by OMDf - Localized Thinning
Hydride layer at the internal surface of the pipe base metal, after Kroll etch.
71
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Micrography by SEMDf - Hydride Formation
Detail of the hydride layer at the internal surface of the pipe base metal, after Kroll etch.
62
VIEW
ML00005 / Apr.2017
Environmental Hydrogen Damage in Ti Pipe
M - Unalloyed TitaniumP - Longitudinal Seam Welded PipeAp - PipingCd - Hydride Formation
Cm - Micrography by SEMDf - Hydride Formation