The Experts below are selected from a list of 6648 Experts worldwide ranked by ideXlab platform
Frank Peter Schimansky - One of the best experts on this subject based on the ideXlab platform.
-
Selective laser melting of a beta-solidifying TNM-B1 Titanium Aluminide alloy
Journal of Materials Processing Technology, 2014Co-Authors: Lukas Löber, Florian Pyczak, Uta Kühn, Frank Peter Schimansky, Jürgen EckertAbstract:Abstract The interest for a wider range of useable materials for the technology of selective laser melting is growing. In this work we describe a new way to optimize the process parameters for selective laser melting of a beta solidifying Titanium Aluminide. This kind of material has so far not been processed successfully by this method. The new approach is easy to conduct and well transferable to other materials. It is based on the fact that the parts generated from selective laser melting can be described by an addition of multiple single tracks. Multiple types of single track experiments are performed and in combination with knowledge from laser welding tests optimized parameter combinations are derived. Compact samples are built with the optimized process parameters and characterized in terms of microstructure, phase composition and mechanical properties. With this technique the generation of a TNMB1 Titanium Aluminide alloy sample with a density greater than 99% could be achieved. The mechanical properties are comparable with material produced by conventional techniques.
-
the characterisation of a powder metallurgically manufactured tnm Titanium Aluminide alloy using complimentary quantitative methods
Practical Metallography, 2011Co-Authors: Martin Schloffer, Florian Pyczak, Frank Peter Schimansky, Thomas Schmoelzer, Svea Mayer, Emanuel Schwaighofer, Gerhard Hawranek, Helmut ClemensAbstract:Abstract In order to be able to use intermetallic Titanium Aluminide in industrial applications, a quick and affordable method of quantitatively analysing their microstructures is required. In the ...
-
temperature induced porosity in hot isostatically pressed gamma Titanium Aluminide alloy powders
Acta Materialia, 2003Co-Authors: Gerhard Wegmann, Rainer Gerling, Frank Peter SchimanskyAbstract:Abstract In this study the occurrence of temperature induced porosity (TIP) in hot isostatically pressed (HIP) compacts of different gamma Titanium Aluminide alloys was investigated. Two gamma Titanium Aluminide alloys Ti-48.9at.%Al and an advanced Niobium containing alloy Ti-46at.%Al-9at.%Nb have been atomized by gas atomization and by centrifugal atomization in an inert gas atmosphere. The alloy powders were studied regarding porosity and the content of inert gas entrapped in the powder particles. Selected powder batches were hot isostatically pressed at 1280 °C and were investigated with respect to TIP evolution after a high temperature exposure to 1390 °C for short and long time periods. It was found that gas atomized Titanium Aluminide alloy powders contain a certain amount of atomization gas, the concentration of which increases with the powder particle size. The amount of inert gas entrapped in centrifugally atomized powders is higher as compared to powders produced by gas atomization. The occurrence of TIP after high temperature annealing of the HIP’ ed compacts depends on the grain size, the processing medium (Argon or Helium), the amount of entrapped inert gas and the annealing time. Guidelines are presented for minimizing or prevention of TIP in γ-TiAl alloys processed by powder metallurgy.
-
prospects for metal injection moulding using a gamma Titanium Aluminide based alloy powder
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2002Co-Authors: Rainer Gerling, Frank Peter SchimanskyAbstract:Abstract Alloy powder of an advanced gamma Titanium Aluminide alloy (γ-TAB: Ti–47Al–4(Mn, Nb, Cr, Si, B) (at.%)) was produced by argon gas atomization. The fine powder ( 2 : 790 μg g −1 , N 2 : 140 μg g −1 ), the sintered and HIP'ed samples are characterized by a considerable increase in O 2 and N 2 . Both types of impurities vary in the depth of the samples in the range of 1600–8000 μg g −1 (O 2 ) and 160–890 μg g −1 (N 2 ). After HIP the microstructure is of duplex type. Tensile tests at room temperature resulted in a yield strength of 410 MPa, an ultimate tensile strength of 430 MPa and a plastic elongation of 0.6%.
D K Aspinwall - One of the best experts on this subject based on the ideXlab platform.
-
surface integrity of a high speed milled gamma Titanium Aluminide
Journal of Materials Processing Technology, 2001Co-Authors: A L Mantle, D K AspinwallAbstract:Abstract The paper is concerned with the surface integrity of a high speed ball end milled gamma Titanium Aluminide, Ti–45Al–2Nb–2Mn–0.8 vol.%, TiB 2 XD™ produced by Howmet, USA. Commercial interest in gamma Titanium Aluminide is centred mainly in the aerospace and automotive sectors. Possible component applications include, compressor blades, swirl nozzles, automotive engine valves and turbo impellers. Machining tests were carried out on a Matsuura FX5 20,000 rpm, prismatic machining centre using 6 mm diameter, coated tungsten carbide ball end tooling. Operating parameters were used that were representative of finish machining. The majority of surface roughness values recorded were 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn tool), cutting speed and angle-of-workpiece, on residual stress was further analysed using a Taguchi orthogonal array. This demonstrated that flank wear and cutting speed had the most significant effect.
-
the effect of machining on the fatigue strength of a gamma Titanium Aluminide intertmetallic alloy
Intermetallics, 1999Co-Authors: S A Bentley, A L Mantle, D K AspinwallAbstract:Abstract Experimental data is presented which compares the effect of grinding and high speed milling (HSM) on the fatigue strength of a gamma Titanium Aluminide intermetallic alloy. Results showed that HSM significantly increased fatigue strength by as much as 200 MPa over polished samples. Measurement and analysis of workpiece subsurface microhardness and microstructure indicated that the high run-out values correlated to high hardness and plastic deformation of the near surface lamellae.
-
surface integrity and fatigue life of turned gamma Titanium Aluminide
Journal of Materials Processing Technology, 1997Co-Authors: A L Mantle, D K AspinwallAbstract:Abstract This paper outlines the effect of single-point turning on the surface integrity and fatigue life of a gamma XD™ Titanium Aluminide (Ti–45Al–2Nb–2Mn–0.8% TiB2) produced by Howmet, USA. Intermetallic materials of this type are currently been evaluated by leading aerospace companies world-wide for use in aeroengine applications (e.g. compressor blades), due to their good high-temperature properties and low density (≈50% of Ni-based superalloys). Workpiece surface integrity defects were found after machining, including deformed lammellae/surface drag, material pull-out/cracking (
S L Semiatin - One of the best experts on this subject based on the ideXlab platform.
-
Hot Rolling of Gamma Titanium Aluminide Foil (PREPRINT)
2010Co-Authors: S L Semiatin, B. Shanahan, F. MeisenkothenAbstract:Abstract : Metal flow and microstructure evolution during the thermomechanical processing of thin-gage foil of a near-gamma Titanium-Aluminide alloy, Ti-45.5Al-2Cr-2Nb, with an equiaxed-gamma microstructure was investigated experimentally and theoretically. Foils of thickness of 200 - 250 micrometers were fabricated via hot rolling of sheet in a can of proprietary design. The variation in gage of the rolled foils was +/-15 micrometers except in very sporadic (local) areas with variations of approximately 60 micrometers relative to the mean. Metallography revealed that the larger thickness variations were associated with large remnant colonies lying in a hard orientation for deformation. To rationalize these observations, a self-consistent model was used to estimate the strain partitioning between the softer (equiaxed-gamma) matrix and the remnant colonies. Furthermore, the efficacy of pre- or post- rolling heat treatment in eliminating remnant colonies was demonstrated and quantified using a static-spheroidization model. The elimination of remnant colonies via spheroidization prior to foil rolling gave rise to improved gage control.
-
Hot rolling of gamma Titanium Aluminide foil
Acta Materialia, 2010Co-Authors: S L Semiatin, B. Shanahan, F. MeisenkothenAbstract:Abstract Metal flow and microstructure evolution during the thermomechanical processing of thin-gage foil of a near-gamma Titanium Aluminide alloy, Ti–45.5Al–2Cr–2Nb, with an equiaxed-gamma microstructure was investigated experimentally and theoretically. Foils of thickness of 200–250 μm were fabricated via hot rolling of sheet in a can of proprietary design. The variation in gage of the rolled foils was ±15 μm except in very sporadic (local) areas, with variations of approximately 60 μm relative to the mean. Metallography revealed that the larger thickness variations were associated with large remnant colonies lying in a hard orientation for deformation. To rationalize these observations, a self-consistent model was used to estimate the strain partitioning between the softer (equiaxed-gamma) matrix and the remnant colonies. Furthermore, the efficacy of pre- or post-rolling heat treatment in eliminating remnant colonies was demonstrated and quantified using a static-spheroidization model. The elimination of remnant colonies via spheroidization prior to foil rolling gave rise to improved gage control.
-
hot workability of Titanium and Titanium Aluminide alloys an overview
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1998Co-Authors: S L Semiatin, V. Seetharaman, I WeissAbstract:Abstract The hot workability of conventional Titanium alloys and Titanium Aluminides is reviewed. For both alloy classes, the influence of hot working variables and microstructure on failure via fracture or flow-localization controlled processes is summarized. The occurrence of wedge cracking and cavitation during bulk forming of α / β alloys with Widmanstatten microstructures or γ Titanium Aluminides with lamellar or equiaxed structures, is examined. In particular, the effects of grain size, grain boundary second phases and process variables on failure are presented. Observations and models of flow localization and cavitation processes which lead to failure during low strain rate, superplastic, tensile-type deformation of Titanium and Titanium Aluminide alloys with fine equiaxed structures, are also described. In the area of flow-localization-controlled failure during bulk forming, the occurrence of shear bands and other flow nonuniformities during both conventional and isothermal hot working processes is reviewed. The influence of material properties, such as flow softening rate and strain rate sensitivity and process variables, which lead to temperature and hence flow nonuniformities, is examined. The flow localization concepts are illustrated for several hot working processes.
-
Hot workability of Titanium and Titanium Aluminide alloys—an overview
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1998Co-Authors: S L Semiatin, V. Seetharaman, I WeissAbstract:Abstract The hot workability of conventional Titanium alloys and Titanium Aluminides is reviewed. For both alloy classes, the influence of hot working variables and microstructure on failure via fracture or flow-localization controlled processes is summarized. The occurrence of wedge cracking and cavitation during bulk forming of α / β alloys with Widmanstatten microstructures or γ Titanium Aluminides with lamellar or equiaxed structures, is examined. In particular, the effects of grain size, grain boundary second phases and process variables on failure are presented. Observations and models of flow localization and cavitation processes which lead to failure during low strain rate, superplastic, tensile-type deformation of Titanium and Titanium Aluminide alloys with fine equiaxed structures, are also described. In the area of flow-localization-controlled failure during bulk forming, the occurrence of shear bands and other flow nonuniformities during both conventional and isothermal hot working processes is reviewed. The influence of material properties, such as flow softening rate and strain rate sensitivity and process variables, which lead to temperature and hence flow nonuniformities, is examined. The flow localization concepts are illustrated for several hot working processes.
-
Can Design for Nonisothermal Pancake Forging of Gamma Titanium Aluminide Alloys
Journal of Engineering for Industry, 1996Co-Authors: V. K. Jain, R. L. Goetz, S L SemiatinAbstract:The design of cans to produce uniform, defect-free gamma Titanium Aluminide alloy pancakes via conventional, nonisothermal forging, was established using finite element modeling (FEM) and laboratory validation trials. The specific problem addressed was ingot breakdown via pancake forging, a process typically comprising a high reduction ratio (∼6 :1) and a moderately high deformation rate (∼1 s -1 ) to minimize the effects of die chilling. Can and process variables investigated in the FEM simulations included can end cap shape and thickness, ram speed, and preheat temperature. The FEM results demonstrated that there is an optimal end cap thickness and ram speed to obtain moderately uniform flow between the can and Titanium Aluminide workpiece. These results were validated through trials on the near-gamma Titanium Aluminide alloy Ti-45.5Al-2Cr-2Nb forged in AlSl type 304 stainless steel cans.
A L Mantle - One of the best experts on this subject based on the ideXlab platform.
-
surface integrity of a high speed milled gamma Titanium Aluminide
Journal of Materials Processing Technology, 2001Co-Authors: A L Mantle, D K AspinwallAbstract:Abstract The paper is concerned with the surface integrity of a high speed ball end milled gamma Titanium Aluminide, Ti–45Al–2Nb–2Mn–0.8 vol.%, TiB 2 XD™ produced by Howmet, USA. Commercial interest in gamma Titanium Aluminide is centred mainly in the aerospace and automotive sectors. Possible component applications include, compressor blades, swirl nozzles, automotive engine valves and turbo impellers. Machining tests were carried out on a Matsuura FX5 20,000 rpm, prismatic machining centre using 6 mm diameter, coated tungsten carbide ball end tooling. Operating parameters were used that were representative of finish machining. The majority of surface roughness values recorded were 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn tool), cutting speed and angle-of-workpiece, on residual stress was further analysed using a Taguchi orthogonal array. This demonstrated that flank wear and cutting speed had the most significant effect.
-
the effect of machining on the fatigue strength of a gamma Titanium Aluminide intertmetallic alloy
Intermetallics, 1999Co-Authors: S A Bentley, A L Mantle, D K AspinwallAbstract:Abstract Experimental data is presented which compares the effect of grinding and high speed milling (HSM) on the fatigue strength of a gamma Titanium Aluminide intermetallic alloy. Results showed that HSM significantly increased fatigue strength by as much as 200 MPa over polished samples. Measurement and analysis of workpiece subsurface microhardness and microstructure indicated that the high run-out values correlated to high hardness and plastic deformation of the near surface lamellae.
-
surface integrity and fatigue life of turned gamma Titanium Aluminide
Journal of Materials Processing Technology, 1997Co-Authors: A L Mantle, D K AspinwallAbstract:Abstract This paper outlines the effect of single-point turning on the surface integrity and fatigue life of a gamma XD™ Titanium Aluminide (Ti–45Al–2Nb–2Mn–0.8% TiB2) produced by Howmet, USA. Intermetallic materials of this type are currently been evaluated by leading aerospace companies world-wide for use in aeroengine applications (e.g. compressor blades), due to their good high-temperature properties and low density (≈50% of Ni-based superalloys). Workpiece surface integrity defects were found after machining, including deformed lammellae/surface drag, material pull-out/cracking (
Matthew S. Dargusch - One of the best experts on this subject based on the ideXlab platform.
-
Microstructural design for thermal creep and radiation damage resistance of Titanium Aluminide alloys for high-temperature nuclear structural applications
Current Opinion in Solid State and Materials Science, 2014Co-Authors: Hanliang Zhu, Tao Wei, David G. Carr, Robert P. Harrison, Lyndon Edwards, Dongyi Seo, Kouichi Maruyama, Matthew S. DarguschAbstract:Microstructure plays an important role in strengthening of metallic materials. Various microstructures can be developed in Titanium Aluminide (TiAl) alloys, which can enable different combinations of properties for various extreme environments in advanced nuclear systems. In the present paper the mechanisms for microstructural strengthening and the effects of various microstructural features on thermal creep and radiation damage resistance of TiAl alloys are reviewed and compared. On the basis of the results, the evidence-based optimum microstructure for the best combination of thermal creep and radiation damage resistance of TiAl alloys is proposed. The heat treatment processes for manufacturing the optimal microstructure are also discussed.
