Development of fine-grain size titanium 6Al–4V alloy sheet material for low temperature superplastic forming
Fine-grained titanium 6Al–4V alloy, which typically has a grain size of about 1–2μm, can be made to superplastic form at around 800°C with special processing. The normal temperature for superplastic forming (SPF) with conventional titanium 6Al–4V sheet material is 900°C. The lower temperature perfor...
Saved in:
Published in | Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 608; pp. 265 - 272 |
---|---|
Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier B.V
01.07.2014
Elsevier |
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | Fine-grained titanium 6Al–4V alloy, which typically has a grain size of about 1–2μm, can be made to superplastic form at around 800°C with special processing. The normal temperature for superplastic forming (SPF) with conventional titanium 6Al–4V sheet material is 900°C. The lower temperature performance is of interest to the Boeing Company because it can be exploited to achieve significant cost savings in processing by reducing the high-temperature oxidation of the SPF dies, improving the heater rod life for the hot presses, increasing operator safety and replacing the chemical milling operation to remove alpha case contamination with a less intensive nitric hydrofluoric acid etchant (pickle). In this report, room temperature tensile tests and elevated temperature constant strain rate tensile tests of fine-grained Ti–6Al–4V sheets provided by the Baoti Company of Xi׳an, China, were conducted according to the test method standards of ASTM-E8 and ASTM-E2448. The relationships among the processing parameters, microstructure and superplastic behavior have been analyzed. The results show that two of the samples produced met the Boeing minimum requirements for low-temperature superplasticity. The successful material was heat-treated at 800°C subsequent to hot rolling above the beta transus temperature, Tβ-(150–250°C). It was found that the sheet metal microstructure has a significant influence on superplastic formability of the Ti–6Al–4V alloy. Specifically, fine grains, a narrow grain size distribution, low grain aspect ratio and moderate β phase volume fraction can contribute to higher superplastic elongations. |
---|---|
Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/j.msea.2014.04.098 |