Inclusions in Ti-6Al-4V investment castings

Cotton, James D.; Clark, L.P.; Reinhart, Theodore L.; Spear, W. S.; Veeck, Stewart; Strabel, George

doi:10.2514/6.2000-1464

Cited by 3 publications

(2 citation statements)

References 13 publications

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“…The USAF Aircraft Structural Integrity Program (ASIP) design methodology currently assumes an embedded 1.0 mm internal flaw [10]; therefore, seeded hard D inclusions in the 1.0 to 6.0 mm diameter range were utilized. Hard D inclusions have been generated from torch cutting and welding operations (foundry spatter) and enter the melt as contamination [9]. To simulate torch cutting on the foundry floor, Ti bar material was melted using an oxy-acetylene torch and was then allowed to solidify.…”

Section: Manufacture Of Inclusionsmentioning

confidence: 99%

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Development and evaluation of a novel inclusion seeding methodology for Ti−6Al−4V castings

2007

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Hard alpha inclusions in titanium (Ti) investment castings are generally known to have detrimental effects on the mechanical properties of these castings. However, actual inclusions are infrequent and occur in random locations in castings. As a result, it is difficult to obtain tensile or fatigue test specimens of titanium castings with inclusions in the gage section. Quantifying the adverse influence of inclusions on the mechanical properties of castings is, therefore, extremely challenging. To address this problem, a novel artificial inclusion seeding methodology was developed to emulate actual Ti investment casting inclusions. Prefabricated inclusions were seeded into machined holes in cast Ti-6Al-4V plates, the holes were back-filled with plugs of the same Ti alloy and were then electron-beam (EB) welded closed. Hot isostatic pressing (HIP) was utilized to incorporate the inclusions fully into the cast titanium material. Finally, the plates were machined to create mechanical test specimens with inclusions centered in the gage region. Test specimens created by means of this novel artificial seeding methodology were evaluated and found to be equivalent to Ti casting specimens containing actual cast-in inclusions.

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Section: Manufacture Of Inclusionsmentioning

confidence: 99%

“…However, large-scale structural titanium investment castings have shown a historical hard D find rate of less than 1 per 100 parts produced [9,12]. This yield rate is too low and unpredictable to generate sufficient data for the aerospace design community to design these castings with confidence.…”

Section: Introductionmentioning

confidence: 99%

Development and evaluation of a novel inclusion seeding methodology for Ti−6Al−4V castings

2007

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Titanium investiment casting defects: A metallographic overview

Cotton

Clark

Phelps

2006

JOM

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Although titanium castings have been used in aerospace structures for decades, those uses have largely been in secondary applications. Expanding the use of titanium castings in critical applications would be encouraged by a better understanding of investment casting defects in titanium alloy systems. This paper describes several types of casting-related defects that are identifi ed as potentially affecting the design life of a structure: inclusions, voids, and weld repair defects.

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