Observations on Delayed Cracking in Welded Structures of Unalloyed Titanium Sheet

Observations on Delayed Cracking in Welded Structures of Unalloyed Titanium Sheet PDF

Author: R. H. Ernst

Publisher:

Published: 1964

Total Pages: 12

ISBN-13:

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A brief study of delayed fracture in a seam-welded titanium panel is summarized in this memorandum. Examination of the fracture surface with electron microscopy showed that the material cleaved, failing in a brittle manner. Although the nature of the embrittlement was not clearly defined, titanium hydride phase was suspected as a prime contributor to failure. Even though the hydrogen content of the titanium was only 65 ppm, hydride embrittlement was thought to have occurred from precipitation of hydride platelets on crystal planes oriented normal to welding stresses. Other work, briefly discussed in the memorandum, has confirmed that hydride platelets in titanium can be oriented by stress and that tensile ductility of Zircaloy (which behaves similarly with respect to hydrogen, to titanium) depends upon hydride orientation. Stress-relief annealing of welded titanium structures is recommended wherever possible to minimize embrittlement by stress-oriented hydrides. (Author).

Recent Developments in Welding Thick Titanium Plate

Recent Developments in Welding Thick Titanium Plate PDF

Author: R. E. Monroe

Publisher:

Published: 1965

Total Pages: 26

ISBN-13:

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This memorandum represents a combined effort by the U.S. Naval Applied Science Laboratory, Brooklyn, New York, and the Defense Metals Information Center to summarize new information on welding thick Ti plate. Thick plate of Ti continues to be of interest to the aerospace and defense industries for possible use in submersibles, armored vehicles, large space boosters, high-speed aircraft, and for pressure vessels. This memorandum generally is limited to information on welding Ti plate that is (1) at least 1 in. thick and (2) that is not covered by DMIC Report 185, The Status and Properties of Titanium Alloys for Thick Plate, June 14, 1963. The general requirements for welding Ti are not repeated here, since they are well documented in references mentioned in the inroduction to the memorandum. Sections have been prepared to cover material developments, welding-process developments, weld properties, and residual welding stresses. (Author).

Porosity in Titanium Welds

Porosity in Titanium Welds PDF

Author: Robert Melvin Evans

Publisher:

Published: 1964

Total Pages: 14

ISBN-13:

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Porosity in fusion welds in titanium has been encountered to some extent in all programs using this joining method. While measures to control cleanliness and to employ good welding techniques have successfully reduced the occurrence of porosity, specific indentification of the various causes of porosity is still lacking. Some factors suspected of causing porosity in titanium welds are hydrogen, cleanliness of joint area, contamination in filler wire, and welding procedures and techniques.

Investigation of Delayed-cracking Phenomenon in Hydrogenated Unalloyed Titanium

Investigation of Delayed-cracking Phenomenon in Hydrogenated Unalloyed Titanium PDF

Author: R. A. Wood

Publisher:

Published: 1961

Total Pages: 22

ISBN-13:

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Three grades of unalloyed titanium were studied to determine the effect of variations in O and N contents on delayed cracking. The bar stock was analyzed for interstitial content, then vacuum annealed to remove most of the H. Large samples of the 1/2-in.-diam vaccum-annealed stock were subsequently hydrogenated to about 90 and 160 ppm H levels. Hydrogen-induced strainaging embrittlement at ambient temperatures in interstitial-containing alphi Ti was not indicated by the results of stress-rupture tests. The results indicate that strain-aging embrittlement does not occur in unalloyed Ti having up to 0.38 wt-% O with as much as 160 ppm H content. However, a noticable effect of H on notch sensitivity of the materials, in the alpha-annealed and especially in the beta-annealed conditions, was observed. It appears probable that H was concentrated in the critical areas by a thermaldiffusion process to create an ultrasensitive zone. Failure might have occurred subsequently as a result of simple overstressing, or by accidentally applied impact stresses, or by a more complicated low-cycle fatigue mechanism. (Author).

Summary of the Eighth Meeting of the Refractory Composites Working Group

Summary of the Eighth Meeting of the Refractory Composites Working Group PDF

Author: E. S. Bartlett

Publisher:

Published: 1964

Total Pages: 26

ISBN-13:

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This memorandum summarizes information on refractory materials and composites as presented at the Eighth Meeting of the Refractory Composites Working Group in Fort Worth, Texas, January 14-16, 1964. This memorandum is based on 45 papers covering a wide variety of subjects ranging from basic studies on oxidation mechanisms to the development of specific pieces of hardware. The papers are reviewed and discussed briefly within the framework of the following four broad areas: materials technology, process technology, specific hardware applications, and evaluation techniques. Included in the section on materials technology are discussions dealing with bulk refractory materials and coatedmetal systems. Hot spraying, chemical vapor deposition, powder processes, joining, and extrusion are discussed in the section on process technology. The specific hardware applications cover rocket-motor components, nose caps, leading edges, hot skins, and fasteners. (Author).

Machining of Titanium Alloys

Machining of Titanium Alloys PDF

Author: C. T. Olofson

Publisher:

Published: 1965

Total Pages: 30

ISBN-13:

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The memorandum summarizes current knowledge concerning the machining of titanium alloys. The memorandum deals with the following conventional machining operations: milling, face milling, peripheral milling, turning, boring, drilling, tapping, and grinding. The last section of the memorandum deals with chemical milling operations.

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