Post on 14-Jun-2018
CHiMaD/SRG31
32nd Annual Meeting
David SnyderSenior Materials Engineer
QuesTek Innovations LLC
March 22, 2016
ICME approach to Additive Manufacturing –
Modeling and Alloy Design
QuesTek Innovations—SRG 201622 March 2016
• Increasing interest in the development of new alloys specifically designed for AM
• Alloy producers, OEMs, government
• Adaptation of traditional wrought/cast alloys to AM processing presents limitations
• AM design considerations:
• Complex thermal histories− Rapid solidification
− Intense residual stresses
− Non-equilibrium microstructures
• Impurity tolerance
• Geometry-dependent behavior (reliability)
• Novel alloy design strategies
QuesTek sees increasing interest in the design and development of improved alloys for additive manufacturing
Motivation
QuesTek Innovations—SRG 201622 March 2016
• DARPA Open Manufacturing “Rapid Low Cost Additive Manufacturing” (Ni superalloys; Honeywell)
• ONR Phase II SBIR “Computational Design of Aluminum Alloys for Use in Additive Manufacturing”
• NAVAIR Phase I SBIR “Development of 7050 T-74 Aluminum Alloy Alternative for use in Additive Manufacturing (AM)
Systems”
• Ti alloys for additive manufacturing (Sciaky EBAM)
• Army Phase I SBIR “Application of ICME to Optimize Processing of State-of-the-art Gear Steels in Additive
Manufacturing”
• AFRL MAI (Honeywell) “ICME Development for Additive Manufactured Aerospace Components”
• Commercial projects and proposals, AM committee participations
Current QuesTek AM project highlights
QuesTek Innovations—SRG 201622 March 2016
Aluminum Alloy Development for Additive Manufacturing
ONR Phase II SBIRAluminum AM for Helicopter Gearbox Housings
NAVAIR Phase I SBIRHigh-strength Aluminum AM for Aircraft Structures
QuesTek Innovations—SRG 201622 March 2016
Project Goals
• Current Al AM alloys are low
performance casting alloys (AlSi12,
AlSi10Mg)
• AM of high-strength Al (e.g. 6061,
7050) limited by Hot Tearing
– Driven by high residual stress, sub-
optimal solidification behavior
• Program Goal: High-strength,
precipitation hardenable Al
optimized for AM
– Structural Alloys
– High-temperature Alloys
Comparison of AlSi10Mg and Al-6061 Processed Through DMLS
B. Fulcher et.al, 2014 SFF Symposium proceedings
Hot tearing in 6061 processed by DMLS
X-Y plane
X-Z plane
QuesTek Innovations—SRG 201622 March 2016
Project Goals
Critical trade-off between Precipitate Strengthening and AM Processability
QuesTek Innovations—SRG 201622 March 2016
Design for Hot Tearing
• Hot tearing susceptibility is (partly) driven by an alloy’s capacity for interdendritic liquid feeding during the final stages of solidification
• Cracking Susceptibility Coefficient (CSC) defined to forecast crack susceptibility from solidification path
CSC correlates well with known castability / DMLS processability
Example non-equilibrium solidification simulation
Decreasing
processability
QuesTek Innovations—SRG 201622 March 2016
Design for Strength
• Thermodynamic calculations inform phase stability as a function of composition
for tailored microstructures and control of processing windows
• Mechanistic strength models utilized to inform composition and processing route to achieve property goals
Mechanistic strength modeling
Quench Sensitivity modeling
QuesTek Innovations—SRG 201622 March 2016
• 7xxx series aluminum for additive manufacturing:– Incorporate novel non-equilibrium Zn-based eutectic for hot cracking resistance
– Computational optimization between eutectic content (processability) and η’-phase strengthening (performance)
Region of combined strength + hot
tearing resistance
Computational Optimization between performance and processing
Integration of material models to visualize trade-off between design metrics
Example Design Integration
iCMDTM
QuesTek Innovations—SRG 201622 March 2016
Feasibility Study: Bead-on-plate
• Experimental study to assess weld crack
sensitivity ahead of atomization and DMLS
• 3 concepts designed for hot tearing and:
– Strength (7000-concept)
– High temperature (2000-concept)
– Corrosion resistance (PH5000-concept)
• Successful elimination of hot cracking,
coupled with high precipitation
hardening response
On par with baseline 7050-T74
QuesTek Innovations—SRG 201622 March 2016
• Phase I feasibility demonstration– Inert gas atomization, 100-lb scale
• Preliminary DMLS process optimization at Stratasys Mfg (Belton, TX)
– EOS M280
– DoE approach to establish effects of process variables on density, microstructure
• Demonstration of high precipitate strengthening with DMLS processability
• In process: 2nd generation prototyping
Prototype DMLS Evaluations
QuesTek Innovations—SRG 201622 March 2016
Ongoing Activities
• Currently in Phase II (2 year program)
• Scaled-up powder production of multiple concept
alloys (>400 lb)– LPW Technology, Inc. (Pittsburgh, PA)
• Extended DMLS evaluations and property
demonstration– Stratasys Direct Manufacturing (Belton, TX)
• Component-level builds
QuesTek Innovations—SRG 201622 March 2016
• QuesTek’s castable Ti alloy has been processed by the EBAM AM process (Sciaky)
• “ICME-designed” to have a refined microstructure on cooling (ideal for AM)
• Enhanced strength + ductility over cast/EBAM Ti-64
AM of QuesTek castable titanium alloys
QuesTek Innovations—SRG 201622 March 2016
AM of high-performance gear steel Ferrium C64
Powder Production
Deposition Optimization
Microstructural Evaluation
Coupon Deposition
Property Validation
• Army need for high-performance AM gear material for use in rapid design/prototype efforts
• Best-in-class Ferrium C64 adapted for AM
• ICME-informed process optimization, combined with leading AM industry knowledge and OEM support
• Evaluate performance and potential for fatigue-driven applications
QuesTek Innovations—SRG 201622 March 2016
• The complexity of AM processing makes it an ideal candidate for ICME methodologies
• Additive manufacturing is unique from cast and wrought processes – alloys should be uniquely customized as well
• Enhanced AM processability and achievable performance
• ICME modeling is being applied to forecast design allowables for parts produced by AM
• More efficient experimentation; Accelerated specification development; Improved confidence
Summary