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Additive Manufacturing of 316L Stainless Steel for Nuclear
EPRI LWR Material Reliability, Chicago IL, August 2016
Myles Connor, Fran Bolger and Ron Horn
GE-Hitachi Nuclear Energy
Xiaoyuan Lou, Peter L. Andresen and
Evan Dolley
GE Global Research
2GEH/GRC 316L Additive
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Topics of Discussion
• Additive Manufacturing Overview
• Why Additive Manufacturing
• Material Properties
– Focus on 316L
Objective: GEH Additive Manufacturing progress.
Feedback, insights, questions, etc…
3GEH/GRC 316L Additive
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Additive (3D Printing) Process
Post Processing (HIP, Heat Treat, Machining, etc.)
Direct Material Laser Melting (DMLM)
Ref: UTEP
Ref. Within Labs, UK
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Value of Additive/3D Metal Printing
Speed of Delivery: Condensed supply chain enables quick response to emergent needs
• No tooling required: fast turnaround time
Design for Performance: Fewer manufacturing limitations allow new designs
• Design-driven manufacturing as opposed to manufacturing-constrained design
Equivalency to Wrought Properties
Enhanced chemistry control: Powder atomization Low Cobalt
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When to Apply Additive• Functional prototypes
• Design for performance enhancement where conventional manufacturing is difficult or not possible
• Weight reduction
• Geometric features enable enhancements
• Cost reduction for complex multi-component assemblies
• High-value products for low volume, specialized or unique components
• Customized designs
AM316L Material Properties
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Summary of Tests To Date
Microstructure Characterization
Tensile Properties
Charpy Fracture Toughness
Stress Corrosion Cracking
AM316L Stainless Steel for Nuclear Environment
Microstructure Characterization1) As-built2) Stress relief3) Solution annealing4) HIP+Annealing
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Top View 2 Top View 2
Cross-section View 4
1
2
3 4
Building
Direction
Stress ReliefAs-built
Cross-section View 4
10GEH/GRC 316L Additive
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Top View 2 Top View 2
Cross-section View 2 Cross-section View 4
1
2
3 4
Building
Direction
Anneal HIP+Anneal
Good density, low porosity
100% Austenitic
Grain size 5 or finer
Microstructure similar to wrought
Tensile and Charpy Impact Test
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Tensile and Charpy Specimen Orientation
Specimens were oriented along vertical, 0 degree
horizontal, and 45 degree horizontal
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Tensile and Charpy Properties
Good ductility (>40%El)
Good yield strength
20
40
60
80
100
120
140DMLS 316L (Vertical)DMLS 316L (Horizontal)Wrought 316LNitronic 50
UTS 0.2% YS Elongation
Stre
ss, k
si o
r Elo
ngat
ion,
%
HIP+Anneal
0
20
40
60
80
100
120
140
Vertical 0 degree 45 degree
Orientation
Toug
hnes
s (ft-
lb)
HIP+Anneal
Typical charpy toughness for annealed
316L @RT: 65~100 ft-lb
AM 316L mechanical properties similar to Wrought 316L
Stress Corrosion Cracking
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20%
Cold Work
Specimen Testing Orientation
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SCC Crack Growth Rate
2ppm O2 (mm/s) 63ppb H2 (mm/s)
HIP+SA, Z-X
Orientation
3.4 X 10-7 1.1 X 10-8
Wrought ~3 X 10-7 ~1 X 10-8
SCC crack growth rate:AM 316L ≤ wrought 316L
25ksi√in, 20%CW, 20 ppb SO42-
Irradiated Properties
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Irradiated Property Strategy
Strong technical basis for wrought 316L similarity
NEET project lead by Dr. Lou (GRC), ORNL, Dr. Was (Univ. Michigan)
• Proton irradiation of DMLM 316L benchmarked against wrought 316L
• Alternate processing property investigation
NSUF ATR irradiation and testing at INL, lead by GEH and INL
Commercial nuclear irradiation of DMLM 316L component and PIE testing
Inspection and AM Standards
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Inspection• Ultrasonic Test (UT) and Radiography Test (RT) similar to
wrought 316L
• Complex geometry = complex inspection
• Only simplest parts can be UT inspected
• Computed Tomography (CT) scan can be used for dimensional validation
• Produce test specimens as part of each build
Cut up, SEM, and mechanical testing of selected complete parts
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Standards AcceptanceASTM draft spec in review
• WK48732- New Standard Additive Manufacturing Stainless Steel Alloy (UNS S31603) with Powder Bed Fusion
• GEH has seat on ASTM F42 committee
– GE Aviation and GE O&G also active on F42 and SAE (aviation)
– GEH also sitting in AWS D20 committee
BWRVIP-84 requirements
Conclusions
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For all the tested material properties (porosity, tensile, charpy, corrosionfatigue, SCC),
AM 316L stainless steel performs similar or better than wrought 316Lstainless steel.
Conclusions
Continue building material property database
• Fatigue, high temp tensile, irradiated, etc.
Qualification/inspection techniques
Material acceptance (ASTM/ASME, BWRVIP, etc.)
Reactor applications
Future Work