Welding simulations: assessment of welding residual stresses and post weld heat treatment

Transcription

1 Welding simulations: assessment of welding residual stresses and post weld heat treatment Etienne Bonnaud and Jens Gunnars, Inspecta Technology AB Third Nordic Conference on Design and Fabrication of Welded Structures, , Stockholm 1

2 Outline Presentation of Inspecta Overview of welding simulations Case study 1: Pressure Vessel manufacture Bending before welding Welding before bending Case study 2: Core Shroud Support of a Nuclear Power Plant Comparison between simulations and measurements Influence of Post Weld Heat Treatment Case study 3: Two-stroke diesel engine support plate Root failure Influence of Post Weld Heat Treatment Conclusion 2

3 Inspecta Group Industries Thermal Power & Heating, Renewables, Nuclear Power, Oil & Gas, Chemical, Pulp & Paper, Metals & Mining, Manufacturing, Rail, Ports, Infrastructure, Real Estate Service areas Inspection, Certification, Testing, Design Review, Quality Assurance, Revisions & Outages, Risk Management, Advisory & Consultancy, Asset Integrity Engineering, Advanced NDT, Life Time & Aging Management, Contract R&D, Training Countries Revenue Employees Sweden, Finland, Norway, Denmark, Poland, Estonia, Latvia, Lithuania 200 MEUR 1600 engineers Offices 80 3

4 Inspecta TECH Advisory & Consultancy Main Competence Areas: Solid mechanics and structural integrity Materials technology, corrosion and welding Risk assessment and project management Services Areas Design verification and optimization, design verification to codes and standards Structural and fatigue analysis, fracture mechanics, plasticity, buckling, dynamics Asset Integrity Engineering Inspection planning, corrosion management, in-depth degradation assessments Risk based inspection planning (RBI), Non-Intrusive Inspection (NII) Fitness-for-service (FFS) evaluation of defects and damage found at revisions Component life assessments, Life time extension strategies, structural integrity Project management Risk, reliability and safety assessments Welding technology, welding simulation Quality assurance, NDT requirements Contract R&D 4

5 Outline Presentation of Inspecta Overview of welding simulations Case study 1: Pressure Vessel manufacture Bending before welding Welding before bending Case study 2: Core Shroud Support of a Nuclear Power Plant Comparison between simulations and measurements Influence of Post Weld Heat Treatment Case study 3: Two-stroke diesel engine support plate Root failure Influence of Post Weld Heat Treatment Conclusion 5

6 Background Weld Residual Stresses Effects from welding processes: - rapid heating and cooling cycles - material submitted to compression and tension - solidification and high temperatures - effects from boundary conditions - large plastic strains - residual stresses arise - compressive and tensile Consequences for component reliability: increased hazard for - stress corrosion cracking - fatigue - fracture 6

7 Background Weld Residual Stresses Measurements Destructive methods relaxation techniques: Hole drilling and measurement by strain gauge Incremental Deep Hole Drilling (IDHD) technique Contour method Slitting, Layer removal Uncertainty in all methods is >20% in challenging cases and assumptions for evaluation Non-destructive methods diffraction techniques: Neutron diffraction X-ray diffraction (standard, synchrotron high energy) Research: Ultrasonic methods, magnetic methods 7

8 Background Weld Residual Stresses Modelling Weld cross section: - geometry - bead size and numbers Material has experienced: - heating and cooling - compression and tension - plastic strains Weld residual stresses simulation: - thermal and mechanical analyses - axial stress - areas in compression and in tension 8

9 Outline Presentation of Inspecta Overview of welding simulations Case study 1: Pressure Vessel manufacture Bending before welding Welding before bending Case study 2: Core Shroud Support of a Nuclear Power Plant Comparison between simulations and measurements Influence of Post Weld Heat Treatment Case study 3: Two-stroke diesel engine support plate Root failure Influence of Post Weld Heat Treatment Conclusion 9

10 Pressure Vessel Analysis description As welded Bending upwards Bending downwards 10

11 Pressure Vessel Results Bending only Hoop stress: -205 MPa -> 200 MPa Welding only Hoop stress: -301 MPa -> 421 MPa 11

12 Pressure Vessel Results: bending followed by welding Bending Downwards: Bending Upwards: Hoop stress: -305 MPa -> 421 MPa Hoop stress: -299 MPa -> 421 MPa 12

13 Pressure vessel Results: welding followed by bending Bending Downwards: Bending Upwards: Hoop stress: -197 MPa -> 195 MPa Hoop stress: -218 MPa -> 219 MPa 13

14 Outline Presentation of Inspecta Overview of welding simulations Case study 1: Pressure Vessel manufacture Bending before welding Welding before bending Case study 2: Core Shroud Support of a Nuclear Power Plant Comparison between simulations and measurements Influence of Post Weld Heat Treatment Case study 3: Two-stroke diesel engine support plate Root failure Influence of Post Weld Heat Treatment Conclusion 14

15 Core Shroud Support Set up and Model 15

16 Core Shroud Support Final Results Simulation result - field plot Path plots Deep hole drilling measurement 16

17 Core Shroud Support Post Weld Heat Treatment Before Post Weld Heat Treatment After Post Weld Heat Treatment Circumferential stress at room temperature After buttering but before attachment weld Post Weld Heat treatment according to standards (7 hours at 620ºC) Important stress release in the Carbon Steel 17

18 Outline Presentation of Inspecta Overview of welding simulations Case study 1: Pressure Vessel manufacture Bending before welding Welding before bending Case study 2: Core Shroud Support of a Nuclear Power Plant Comparison between simulations and measurements Influence of Post Weld Heat Treatment Case study 3: Two-stroke diesel engine support plate Root failure Influence of Post Weld Heat Treatment Conclusion 18

19 Support plate root failure 19

20 Support plate Post Weld Heat Treatment 20

21 Conclusions Weld residual stress simulations give reliable results. Very good agreement between simulations and measurements confirms that both simulations and experiments give accurate results. Post Weld heat treatment is usually beneficial but can also be detrimental. 20 years of experience within weld residual stresses simulations at Inspecta. 21

22 22 Thank you for your attention!

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