Evaluation of Tensile Properties and their Correlation with Microstructural Characteristics of a Closed Die Forging of Iso-symmetrical Aerospace Grade Ti-6Al-4V Alloy

Anuradha Nayak Majila; D. Chandru Fernando; S.N. Narendra Babu; B.V.A. Patnaik; N.E. Prasad

doi:10.14429/dsj.65.7232

Anuradha Nayak Majila Gas Turbine Research Establishment, Bangalore
D. Chandru Fernando Gas Turbine Research Establishment, Bangalore
S.N. Narendra Babu Gas Turbine Research Establishment, Bangalore
B.V.A. Patnaik Gas Turbine Research Establishment, Bangalore
N.E. Prasad Regional Centre for Military Airworthiness (Materials), CEMILAC, Hyderabad

DOI: https://doi.org/10.14429/dsj.65.7232

Keywords: ?-? titanium alloy, primary ?, prior ?, closed die forging, tensile test, microstructure, fractrography

Abstract

In the present technical paper an iso-symmetrical forging in titanium alloy, i.e., Ti-6Al-4V is chosen for cut-up evaluation and study of mechanical properties and their correlation with microstructural characteristics. Tensile test specimens were extracted from rim, web and bore regions of the forgings aligned in radial and tangential directions. Test specimens varying from various locations were extracted to conduct the tests (ASTM E8) at various temperatures from room temperature to 300 °C. Statistical analyses of the tested data were carried out to quantify the variation in tensile properties along rim, web, and bore regions at room temperature. Effects of radial and tangential alignments of specimens at room temperature was also studied. Among the different test specimens, the specimen that exhibited mechanical properties close to average values were further subjected to microstructural and fractographic investigations using optical and scanning electron microscopes. These studies revealed that there is a marginal inhomogenity in the microstructure of the forgings and this variation controls the mechanical properties and fracture characteristics of the material. Microstructure marginally varies from rim to bore region. Similarly, along the thickness of the forging, there is a small variation in the microstructure. The aforementioned correlations have established the fact that the microstructure variations from different locations and among different specimen orientations have resulted in mild variation in the tensile properties.

Defence Science Journal, Vol. 65, No. 2, March 2015, pp.171-178, DOI:http://dx.doi.org/10.14429/dsj.65.7232

Author Biographies

Anuradha Nayak Majila, Gas Turbine Research Establishment, Bangalore

Anuradha Nayak Majila joined DRDO after completing BTech in Metallurgical engineering in 2001 and working for GTRE since 2005. The areas of interest include high strain rate testing, impact testing, foreign object damage evaluation of aero engines and aircraft components. He has worked for several projects for ADA, CABS, HAL, NAL, Delhi-Metro Rail and Honey Well Tech Ltd. For the past 6 years has been working for aero engine and characterization, cut-up evaluation of forgings and is In-charge of AMTL, which is a testing set up of GTRE.

D. Chandru Fernando, Gas Turbine Research Establishment, Bangalore

Mr D. Chandru Fernando is presently working as a scientist at GTRE after completing his BE in Metallurgical Engineering. He is a Life Member of AeSI, IIM. He is working in the areas of material testing, data analysis and evaluation of aero engine materials.

S.N. Narendra Babu, Gas Turbine Research Establishment, Bangalore

Mr S.N. Narendra Babu Graduate in Science and Mechanical Engineering from Bangalore University Worked as Engineer- Product devpt and projects with M/s Panyam’s Steel Wire Division for development of spring wires. Joined as Jr Project Engineer with Engg Projects India Ltd for the Bell Annealing Furnace project in Cold rolling mills at Bokaro Steel plant. Worked at DMRL for the Technology Devpt centre for Titanium till 1997. Working at GTRE since 1997 for Kaveri Materials Development Programme and Heading the Materials Application Group of GTRE since 2006. 15 publications on various material characterisation works in National and international journals and conferences.

B.V.A. Patnaik, Gas Turbine Research Establishment, Bangalore

Mr B.V.A. Patnaik obtained AMAeSI (Aerodynamics) from Aeronautical Society of India in 1985 and MTech (Aerospace Engineering) from IIT Kharagpur in 1998. Stress analysis of gas turbine components, Material selection and material characterization of aerospace materials. Life evaluation of the Critical components of Gas Turbine Engine. Development of Life monitoring algorithms (LCF Counter), Establishing HCF life monitoring strategies using Stress analysis results, NSMS and strain gauge data from Engine testing. Creep life analysis and development of Creep Fatigue interaction models of Gas Turbine materials. Delivered lectures on structural analysis of GAS Turbine components at DIAT Pune, VSSC and Finite element methods at GTRE. Study on life extension of gas turbine engines. Study and development of Endurance, AMT test cycles for gas turbine engine. Currently Heading Structural Mechanics group, Materials Group & Engine Health and Life Analysis Group as technology Director at GTRE. Member of national Core committee of Integrated Vehicle Health Management (IVHM) constituted by Director of Aeronautics.

N.E. Prasad, Regional Centre for Military Airworthiness (Materials), CEMILAC, Hyderabad

Dr N. Eswara Prasad, FIE, FIIM, FAPASc., obtained BTech (in1985) and PhD (in 1993) in Metallurgical Engineering from IIT-BHU, Varanasi, India, and joined the Defence Rersearch and Development Organisation (DRDO) in 1985. Since then, Dr Prasad worked in the fields of Design, Development, Life Prediction and Airworthy Certification, leading to Production of Aero Materials, viz. Al and Al-Li alloys; Mo and Ti Intermetallics; Ti and Ni based high temperature alloys; Monolithic ceramics such as Structural Alumina, Graphite and SiC; Carbon, Silica and SiC-based Continuous – fibre ceramic – matrix composites (CFCCs) and published more than 150 international papers and conference proceedings and edited 12 books, including an Elsevier’s Monograph on Aluminum – Lithium Alloys: Processing, Properties and Applications. Dr Prasad is the recipient of several awards and recognitions, including Young Scientist (ISCA, India – 1991), Young Metallurgist (IIM, India – 1994), Humboldt Research Fellow (AvH-Bonn, Germany – 1998), Visiting Scientist (MPI-Stuttgart, Germany – 1998), Binani Gold Medal (IIM, India – 2006), Metallurgist of the Year (Min. of Steel, Govt. India – 2010) and Dr VM Ghatge Award (AeSI, India – 2014). Dr Prasad is presently the Regional Director of Regional Centre for Military Airworthiness (Materials), CEMILAC at Hyderabad, India