Mechanical properties of a titanium blading alloy. Final report. [Ti-6 Al-4V]

Technical Report · Sat Oct 01 04:00:00 EDT 1983

OSTI ID:5277940

Luetjering, G; Peters, M

The Ti-6Al-4V alloy is being developed for application as a blading material for long blades in the last several rows of fossil low-pressure steam turbines because of its superior corrosion resistance compared to the conventional 12 to 13% chromium martensitic steel. This study had the objective of optimizing the microstructure and processing of the Ti-6Al-4V blading alloy. Processing and heat treatment variables were studied whereby the Ti-6Al-4V alloy could be produced in a variety of microstructures ranging from equiaxed ..cap alpha.. phase with intergranular ..beta.. phase to fully lamellar (..cap alpha..+..beta..) phases and a special microstructure designated as the bimodal microstructure consisting of equiaxed ..cap alpha.. grains in a matrix of lamellar (..cap alpha..+..beta..) phases. For blading it is also important to control the modulus of elasticity, which governs the frequency of vibration of the blades. It was found that the modulus is controlled primarily by the fabrication direction and temperature. After working at temperatures low in the (..cap alpha..+..beta..) field, the alpha phases develop a strong basal (B) texture, with the basal (0001) planes parallel to the rolling plane. At high working temperatures the basal planes are oriented perpendicular to the rolling plane and parallel to the working direction. This texture is called a transverse (T) texture. Unidirectional working results in mixed basal plus transverse (BT) textures. The modulus of elasticity is highest in the direction perpendicular to the basal plane and least in the direction parallel to the basal plane. The optimum condition for the Ti-6Al-4V alloy for blading was found to be a fine bimodal structure with mixed BT texture. Detailed processing recommendations for achieving this structure are presented.

• Research Organization: Technische Univ. Hamburg-Harburg, Hamburg (Germany, F.R.); Bochum Univ. (Germany, F.R.). Inst. fuer Werkstoffe
• OSTI ID: 5277940
• Report Number(s): EPRI-CS-2933; ON: DE84920112
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360101* -- Metals & Alloys-- Preparation & Fabrication
ALLOYS
ALUMINIUM ALLOYS
CRYSTAL STRUCTURE
FABRICATION
HEAT TREATMENTS
MACHINERY
MATERIALS
MATERIALS WORKING
MICROSTRUCTURE
OPTIMIZATION
STEAM TURBINES
THERMOMECHANICAL TREATMENTS
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
TURBINE BLADES
TURBINES
TURBOMACHINERY
VANADIUM ALLOYS