Program Organizers: Prof. Isaac Weiss, Prof. Raghavan Srinivasan, Mechanical and Materials Engineering Dept., Wright State University, Dayton, OH 45435;. Dr. Paul Bania, Timet Corporation, Timet-Henderson Technical Laboratory, P.O. Box 2128, Henderson, NV 89009; Prof. Daniel Eylon, Graduate Materials Engineering, University of Dayton, Dayton, OH 45409
Thursday, AM Room: B8
February 8, 1996 Location: Anaheim Convention Center
Session Chairpersons: J. Ault, Precision Castparts Corp., Portland, OR 97206; D. E. Larsen, Howmet Corporation, Whitehall, MI 49461
8:30 am Invited
THE CORRELATION OF CREEP RESISTANCE TO HEAT TREATED MICROSTRUCTURE IN INVESTMENT CAST GAMMA ALLOYS: D. E. Larsen, Howmet Corporation, Whitehall, MI 49461, D.Y. Seo and T.R. Bieler, Michigan State University, East Lansing, MI 48824
Cast gamma titanium aluminides are gaining acceptance as replacements for superalloy and steel components in aerospace, automotive and industrial applications. Components cast from these alloys can operate at temperatures up to 1500deg.F at half the weight of the components they replace. Most applications of cast gamma components require good creep resistance to meet component life requirements. Four heat treatments were developed and applied to investment cast Ti-47Al-2Nb-2Mn (at%)+.8v%TiB2 XD`, Ti-45Al-2Nb-2Mn(at%)+0.8v%TiB2 XD and Ti-47Al-2Nb-2Cr (at%) alloys in an effort to enhance creep properties with a decrease in heat treatment time compared to current practice. Results show that the creep resistance of the Ti-47Al-2Nb-2Mn+0.8v%TiB2 XD and Ti-47Al-2Nb-2Cr alloys can be significantly altered, up to 3X, through heat treatment. However, the creep resistance of the Ti-45Al-2Nb-2Mn+0.8v%TiB2 XD alloy was virtually unaffected. The variation, or lack of variation, in creep resistance with heat treatment can be explained by differences observed in the microstructures produced by the various heat treatments. Both creep resistance data and microstructural observations obtained using optical, SEM, EDS, and TEM techniques will be presented and discussed.
DEVELOPMENT OF CAST Ti-1100 STRUCTURAL COMPONENTS FOR ADVANCED GAS TURBINE ENGINES: James Ault, Precision Castparts Corp., Portland, OR 97206; Paul Allen, Titanium Metals Corp., Henderson, NV 89009; Robert Testin, Allison Engine Co., Indianapolis, IN 46206
Advanced gas turbine engines require more temperature capable lightweight structures to achieve aggressive performance goals. Allison Engine Company's AE2100/AE3007/T406 family of engines features a Ti-6Al-2Sn-4Zr-2Mo-.08Si (Ti-6242S) diffuser/combustor case with a cast diffuser. Growth versions of this engine will require titanium alloy capability beyond that of Ti-6242S, if the weight penalty of a nickel-base diffuser/combustor case is to be avoided. TIMETAL 1100 (TI-1100) is a new generation, high temperature titanium alloy offering improved temperature capability over Ti-6242S. This paper reviews the development of a Ti-1100 diffuser casting for evaluation in an Allison Engine Company AE301X/ Advanced T406 gas generator core. Casting and manufacturing issues, as well as mechanical properties of cast Ti-1100 relative to Ti-6242S, are discussed. Foundry produceability and mechanical property data suggest that Ti-1100 is readily castable and offers up to 100deg.F additional temperature capability over Ti-6242S. Engine durability testing of an all Ti-1100 diffuser/combustor prototype in an AE 301X core will commence in early 1996.
SIMULATION OF MULTICOMPONENT EVAPORATION IN ELECTRON BEAM MELTING AND REFINING: A. Powell, J. Szekely, Massachusetts Institute of Technology, 77 Massachusetts Ave., Rm. 8-135, Cambridge, MA 02139; J. VanDen Avyle, B. Damkroger, Liquid Metal Processing Laboratory, MS 1134, Sandia National Laboratory, PO Box, 5800, Albuquerque, NM 87185
Experimental results and a mathematical model are presented to describe differential evaporation rates in electron beam melting of titanium alloys containing aluminum and vanadium. Experiments characterized the evaporation rate of commercially pure titanium and vapor composition over titanium with up to 6% Al and 4.5% V content as a function of beam power, scan frequency and background pressure. This model is made up of a steady-state heat and mass transport model of a melting hearth and a model of transient thermal and flow behavior near the surface. Activity coefficients for aluminum and vanadium in titanium are roughly estimated by fitting model parameters to experimental results. Based on the ability to vary evaporation rate by 10-15% using scan frequency alone, we discuss the possibility of on-line composition control by means of intelligent manipulation of the electron beam.
RAPID SOLIDIFICATION PROCESSING OF TITANIUM ALLOYS: Mohit Sisodia, Department of Metallurgical Engineering Malaviya Regional Engineering College Jaipur-17, India
Paper lucidly explains and compares the major Rapid Solidification (RS) of Ti-alloys techniques currently available. These are classified in two broad categories i) drop formation (which includes all atomization techniques) ii) stabilization of liquid, steam or surface. Salient features of more than 25 techniques are discussed at length, with much emphasis on arc plasma and free jet, melt spinning. Later one analytically comprises wheel and crucible materials, process atmosphere, crucible design, heating methods process parameters and their relationship to melt composition are described. Practical solutions to this process problems are also analysed. Besides it, guidelines for selection of alloying additives along with a new approach of its processing in the devitification of Titanium rich glasses are introduced. Apart from the microstructure of RS Ti alloys its preliminary results on the age-hardening response and thermal stability are critically reviewed.
RECENT PROCESS DEVELOPMENT OF TITANIUM SPONGE PRODUCTION IN INDIA: Mohit Sisodia, Department of Metallurgical Engineering, Malaviya Regional Engineering College Jaipur-17, India
This review contemplates the recent advances and innovations in titanium technology in India. Titanium and its alloys have emerged as the most important non-ferrous metal and finds extensive applications in the field of aerospace and general engineering due to its physical properties. Its pure form is prepared by Titanium tetrachloride which is obtained by chlorination of oxide followed by reduction in presence of liquid Mg/Na. The process is complex and is restricted to a few countries like U.S.A., France, China, etc., In fact, India has a few rich deposits of this metal in eastern and southern beach sand region along with the production facilities. The present paper discusses the statistically analyses of the efforts of Research and Development with emphasis on the current status of commercial production.
10:20 am BREAK
CASTING TECHNOLOGY FOR GAMMA TITANIUM ALUMINIDE VALVES: D. Eylon, P. Jones, M. Keller, W.J. Porter III, Graduate Materials Engineering, University of Dayton, Dayton, OH 45409
Gamma titanium aluminide alloys are considered for automotive applications in exhaust valves. The use of such valves has already been demonstrated in automobile engines. The challenge at the moment is to develop a cost effective mass production method using casting technology. This paper will discuss technologies investigated in the EMTEC program.
THERMOHYDROGEN TREATMENT OF SHAPE CAST TITANIUM ALLOYS: A.A. Ilyin, V.K. Nosov, A.M. Mamonov, V.N. Uvarov, A.V. Alexandrova, Moscow State University of Aviation Technology, K. Tsilkovsky, Metals Science Dep., Petrovka St. 27, K-31, Moscow, Russia, 103767
Shape casting is one of the most economical and technologically easy processing methods for the production titanium alloy components. However, titanium shape casting application in an industrial scale is limited by low level of their mechanical properties, especially fatigue. We developed new technological methods of cardinal improvement of structure and casting porosity limitation for Ti-6Al-4V (VT6) and high-strength Ti-5.5Al-4V-2Mo-1Cr-0.5Fe (VT23) alloys. This method is based on combinations of HIP and thermohydrogen treatment (THT), they are directed on fatigue properties of shape castings improvement. The results of this testing shown, that suggested treatment strongly increase the cyclic endurance of both alloys. Thus, the number of cycles before fracture for VT6 samples at 500MPa loading increased in more than two times, in comparison with as-cast conditions and secure about 105 cycles. The endurance level for VT23 alloy on 107 base grew from 300 MPa in as-cast condition to 580 MPa after HIP and THT, and it exceeded the level of properties, achieved after strengthening heat treatment (quenching + ageing) of deformed semiproducts. The best fatigue resistance is ensured at the stressed not higher 0.6-0.8 of the ultimate tensile strength. In this suggested technology the castings surface oxidation is eliminated, the rates of heating and cooling are limited to 1-3 K/s. This is very important for near net shape castings of complicated configuration.
HYDROGEN TECHNOLOGY OF TITANIUM ALLOYS ON Ti3Al BASE: A.A. Ilyin, V.K. Nosov, A.M. Mamonov, V.N. Uvarov, A.V. Alexandrova, Moscow State University of Aviation Technology, K. Tsilkovsky, Metals Science Dep. Petrovka St. 27, K-31, Moscow, Russia, 103767
In this work the effect of hydrogen on the ductility and resistance to deformation of the three titanium intermetallic (Ti3Al) based alloys in system Ti-Al-Mo-Zr, Ti-Al-Nb-V-Zr and Ti-Al-Nb-Mo-Zr with different content of ß-stabilizing elements was investigated. Deformation temperature and hydrogen concentration in alloys were chosen according to the alloy-hydrogen equilibrium phase diagrams. Drop forging and rolling of the Ti3Al base alloys were carried out in service conditions with the use of hydrogen plastification, that gives a possibility to deformation conditions applied at [[alpha]]-and ([[alpha]]+ß)-heat-resistant titanium alloys - T=850-950deg.C, instead of T=1100-1250deg.C for alloys which are not hydrogen alloyed. The hydrogen plastification using not only increases the alloys plasticity but together with thermohydrogen treatment (THT) allows to increase their ductility at room and working temperature. Extruded with the use of hydrogen plastification process followed by thermo-hydrogen treatment compressor blades made of Ti-Al-Nb-V-Zr alloy showed the following properties at room temperature: tensile strength 1330 MPa, yield strength 1196 MPa, elongation 3.3%, contraction 2.8%. At a temperature of 650deg.C tensile strength 885 MPa, yield strength 802 MPa, elongation 33.6%, contraction 53.5% were achieved.
FOUNDRY INVOLVEMENT IN ALLOWABLES: Dale L. McLellan, McLellan & Associates, Bellevue, WA 98008
Founders are faced with various obstacles when marketing their products for
aerospace structural applications. They must convince airframers that casting
offer cost and weight benefits over traditionally fabricated and machined
parts. Even before a candidate part is manufactured assurances must be made for
dimensional capabilities and control of tolerances. Consideration must also be
given to the subject of mechanical properties suitable for design. Such
properties, referred to as allowables, have always been established by
airframers since they are responsible for certification of all structures to
regulatory agencies. This paper concludes that statistical development of
allowables for any material, should preclude the necessity of applying any
other reduction factors. Otherwise, there would be no reason for the cost and
time required to obtain such properties. Furthermore, founders should be
involved in determining the allowables as they pertain to the development of
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