Design and Develop PM Processes for optimum Performance/Cost ratio Ti Z. Zak Fang, Pei Sun, and Hongtao Wang Dept. of Metallurgical Engineering, University of Utah
Outline Conventional manufacturing routes of Ti alloys and components Examine various existing separate processing techniques Assemble a set of processes that together yield optimum performance/cost (P/C) ratio
Conventional Manufacturing Routes Cradle to Gate Mineral Sponge Melt Ingot Wrought - Mill products Casting Fabrication Machining Finished products HDH Ti Powder Blended powder Alloyed Powder Cold press / compaction HIPing Billets Vacuum Sintering Finished products
Existing Manufacturing Routes Improved Powder Metallurgy Approaches Ti metal or alloy Powder CHIP Process* - Dynamet Technology, Inc. CIP Vacuum Sintering HIPing Extrusion Forging Finished products * S. Abkowitz et al., Advanced Materials and Processes, 136(1) 1989, pp. 31-34 4
Existing Manufacturing Routes Improved Powder Metallurgy Approaches Sintering of TiH 2* - Ukraine IMP and ADMA Inc TiH 2 powder Cold isostatic pressing uniaxial die compaction Powder rolling compaction Injection molding Vacuum Sintering Extrusion Forging Finished products *O. M. Ivasishin et al., Key Engineering Materials, 188, 2000, pp. 55-62 V. A. Duz et al., Titanium 2008 24 th Annual ITA conference & Exhibition, Las Vegas, Nevada, 2008 V. A. Drozdenko et al.(adma Products, Inc.), US Patent 6,638,336 (2003) V. A. Duz et al., US Patent 7,993,577 B2 F. H. Froes et al., International Materials Reviews, 1990, 35 (3), pp. 162-182
Existing Manufacturing Route Issues that still plague PM Ti: Fatigue performance, Fracture toughness Oxygen and other impurity level Residual porosity Coarse lamellar as-sintered microstructure High pressure processes cost Post-sintering thermal mechanical processes cost High performance/cost ratio P/C?
Searching for a manufacturing route --- Optimum performance/cost (P/C) ratio To achieve both Low Cost and High Performance objectives: Low cost raw material powder Melt-less, blend elemental powder (BE) NNS compaction Meet microstructure and property requirements in as-sintered state No or minimum post-sintering mechanical working, and/or machining
Searching for a manufacturing route --- Optimum performance/cost (P/C) ratio Low Cost Powder NNS Compaction Pressure-less sintering Post-sintering Processing Finished products Sponge fine Uniaxial press Vacuum sintering No/min. cold/hot working ITP powder CIP Sintering in Ar Min. machining HDH powder Injection molding Sintering in H 2 Heat treatment TiH 2 powder Automated CIP Pneumatic isostatic forging FFC powder * Not an exhaustive list. A variety of new powder production methods are available in literature. References available.
Searching for a manufacturing route --- Optimum performance/cost (P/C) ratio Automating CIP: Dry Bag CIP* Automated Process* *Avure Technologies Inc., http://hasmak.com.tr/tozpdf/cip-dry- Bag-Sistemi.pdf
Searching for a manufacturing route --- Optimum performance/cost (P/C) ratio Near-Net-Shape CIP Sinter Machine Knee Hip Stem
Searching for a manufacturing route --- Optimum performance/cost (P/C) ratio Sintering Ti in Hydrogen Atmosphere* Ar+H 2 Green Parts Continuous (?) sintering furnace Optional Vacuum Furnace * Z. Z. Fang et al., Hydrogen Sintering of Titanium to Produce High Density Fine Grain Titanium Alloys, US Patent and Journal Publications Pending. ** J. Qazi, J. Rahim, F. Fores, O. Senkov, A. Genc, Metallurgical and Materials Transactions A, 32 (2001) 2453-2463 Fig. 1 Ti-6Al-4V-H phase diagram. [**]
Hydrogen sintering refine grain microstructure Similar to THP* (ref. F. H. Froes, O. N. Senkov, J. I. Qazi, Int. Mater. Rev. 2004, 49, 227.): refine grain sizes by controlling H 2 content and phase transformation during sintering a b c d e Microstructures produced by vacuum sintering of TiH 2 (a. SEM image), hydrogen sintering of TiH 2 (b. SEM image; c. STEM image), typical wrought processes (d. SEM University image) of and Utah vacuum Metallurgical sintering Engineering of Ti metal powder (e. SEM image)
Hydrogen sintering high strength & ductility Impurity concentrations and tensile properties of vacuum-sintered and hydrogen-sintered Ti-6Al-4V Tensile strength (MPa) 0.2% Yield strength (MPa) Elongation (%) O (wt%) H (wt%) C (wt%) N (wt%) ASTM B348 895 828 10 0.20 0.015 0.08 0.05 Vacuumsintered 982 859 12 0.302 ±0.044 0.004 ±0.002 0.080 ±0.012 0.025 ±0.007 Hydrogen -sintered 1036 943 15 0.308 ±0.07 <0.003 ---- ----
Searching for a manufacturing route --- optimum performance/cost (P/C) ratio Pneumatic Isostatic Forging (PIF)* Pressurizer As-sintered parts Preheat furnace Pressurization vessel (20K~60K psi) PIF *Edwin S. Hodge et al., (AMETK, Inc) US Patent 5,816,090 (1998) AMETK, Inc. http://www.ametekthermalmanagement.com/snippet.cfm?snippet_id=1026
Design and Develop PM Processes for High Performance/Cost Ratio Ti Summary High density, ultrafine grain, low oxygen HDH /TiH 2 /ITP powders; NNS, Ar/H 2 - atm. sintering, (optional) one-step forging or PIF Max Performance Cost Commercial reality check: Not fatigue-sensitive parts Secondary components for aerospace industry, Medical implants Consumer products Auto applications? 15