Change search
ReferencesLink to record
Permanent link

Direct link
Microstructure and phase transformation of Ti-6Al-4V
Luleå tekniska universitet.
2002 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The research described in the thesis concerns phase transformations and fatigue properties in the Ti-6Al-4V alloy. The need to weld the alloy for certain engine components can expose the alloy locally to non-optimum thermal cycles and it is therefore of importance to gain an understanding of the kinetics involved in the phase transformations during heating and cooling. Moreover, for the purpose of modelling and computer simulations of heat treatments and welding processes, quantitative descriptions of the transformation are necessary. One focus in this work has been to examine the feasibility of using high temperature X-ray diffraction (HT-XRD) to study the phase transformation kinetics. In addition, two components of Ti- 6Al-4V produced by ring-rolling and closed die forging, respectively, showed unexpected differences in low cycle fatigue (LCF) under certain loading conditions. Quantitative metallographic studies and texture examinations were conducted in order to find possibly reasons for the observed difference in fatigue properties. The HT-XRD technique was successfully used to monitor the alpha-to-beta transition during heating and the beta-to-alpha transition during cooling and including the transformation kinetics during isothermal hold. From the recorded spectra the thermal expansion properties for the alpha and beta phases could be extracted up to a temperature of 1050°C, enabling the determination of the overall thermal expansion for the alloy by using rule of mixture (ROM) calculations. Quantitative metallographic studies revealed that the closed die forged material exhibited a finer primary alpha grain size and a finer Widmanstätten platelet colony size which would be expected to provide a superior resistance to fatigue crack initiation. Observed differences in the texture of the two materials as determined by electron back-scattered diffraction might also have contributed to the difference in fatigue properties.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2002. , 31 p.
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757 ; 2002:30
Research subject
Material Mechanics
Identifiers
URN: urn:nbn:se:ltu:diva-18361Local ID: 832034e0-c42d-11db-9ea3-000ea68e967bOAI: oai:DiVA.org:ltu-18361DiVA: diva2:991369
Note
Godkänd; 2002; 20070224 (ysko)Available from: 2016-09-29 Created: 2016-09-29Bibliographically approved

Open Access in DiVA

fulltext(14696 kB)63 downloads
File information
File name FULLTEXT01.pdfFile size 14696 kBChecksum SHA-512
c159986771f2dbe1d0ae4f33197bfbc6cdde478eb5bdcd1cdd36db425c5ab4d1eda80b89acd379b98399c3348d9830e7ee6ac10aa73e40d9a29f9aeef6e382e7
Type fulltextMimetype application/pdf

Search outside of DiVA

GoogleGoogle Scholar
Total: 63 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 24 hits
ReferencesLink to record
Permanent link

Direct link