Additive Manufacturing of 316L Stainless Steel for Nuclear

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1 Additive Manufacturing of 316L Stainless Steel for Nuclear Myles Connor, Fran Bolger and Ron Horn GE-Hitachi Nuclear Energy Xiaoyuan Lou, Peter L. Andresen and Evan Dolley GE Global Research EPRI LWR Material Reliability, Chicago IL, August 2016

2 Topics of Discussion Additive Manufacturing Overview Why Additive Manufacturing Material Properties Focus on 316L Objective: GEH Additive Manufacturing progress. Feedback, insights, questions, etc 2

3 Additive (3D Printing) Process Direct Material Laser Melting (DMLM) Ref. Within Labs, UK Ref: UTEP Post Processing (HIP, Heat Treat, Machining, etc.) 3

4 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 manufacturingconstrained design Equivalency to Wrought Properties Enhanced chemistry control: Powder atomization Low Cobalt 4

5 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 5

6 AM316L Material Properties

7 Summary of Tests To Date AM316L Stainless Steel for Nuclear Environment Microstructure Characterization Tensile Properties Charpy Fracture Toughness Stress Corrosion Cracking 7

8 Microstructure Characterization 1) As-built 2) Stress relief 3) Solution annealing 4) HIP+Annealing

9 As-built Top View 2 Stress Relief Top View Building Direction Cross-section View 4 Cross-section View

10 Anneal Top View 2 HIP+Anneal Top View Building Direction 3 4 Cross-section View 2 Cross-section View 4 Good density, low porosity 100% Austenitic Grain size 5 or finer Microstructure similar to wrought 10

11 Tensile and Charpy Impact Test

12 Tensile and Charpy Specimen Orientation Specimens were oriented along vertical, 0 degree horizontal, and 45 degree horizontal 12

13 Stress, ksi or Elongation, % Toughness (ft-lb) Tensile and Charpy Properties HIP+Anneal DMLS 316L (Vertical) DMLS 316L (Horizontal) Wrought 316L Nitronic HIP+Anneal UTS 0.2% YS Elongation 20 0 Vertical 0 degree 45 degree Orientation Good ductility (>40%El) Good yield strength Typical charpy toughness for annealed 65~100 ft-lb AM 316L mechanical properties similar to Wrought 316L 13

14 Stress Corrosion Cracking

15 Specimen Testing Orientation 20% Cold Work 15

16 SCC Crack Growth Rate 25ksi in, 20%CW, 20 ppb SO 4 2- HIP+SA, Z-X Orientation 2ppm O 2 (mm/s) 63ppb H 2 (mm/s) 3.4 X X 10-8 Wrought ~3 X 10-7 ~1 X 10-8 SCC crack growth rate: AM 316L wrought 316L 16

17 Irradiated Properties

18 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 18

19 Inspection and AM Standards

20 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 20

21 Standards Acceptance ASTM draft spec in review WK 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 21

22 Conclusions

23 Conclusions For all the tested material properties (porosity, tensile, charpy, corrosion fatigue, SCC), AM 316L stainless steel performs similar or better than wrought 316L stainless steel. Future Work Continue building material property database Fatigue, high temp tensile, irradiated, etc. Qualification/inspection techniques Material acceptance (ASTM/ASME, BWRVIP, etc.) Reactor applications 23

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