Welding simulations: assessment of welding residual

Welding simulations: assessment of welding

residual stresses and post weld heat treatment

Etienne Bonnaud and Jens Gunnars, Inspecta Technology AB

2016-09-281

Third Nordic Conference on Design and Fabrication of Welded Structures, 2016-09-29, Stockholm

Outline

2

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

2016-09-28

2016-09-283

Inspecta Group

Industries Thermal Power & Heating, Renewables, Nuclear Power,

Oil & Gas, Chemical, Pulp & Paper, Metals & Mining,

Manufacturing, Rail, Ports, Infrastructure, Real Estate

Service areasInspection, 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 Sweden, Finland, Norway, Denmark,

Poland, Estonia, Latvia, Lithuania

Revenue 200 MEUR

Employees 1600 engineers

Offices 80

2016-09-284

■ 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

Inspecta TECH – Advisory & Consultancy

Outline

5

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

2016-09-28

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

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Background – Weld Residual Stresses Measurements

7

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

2016-09-28

Background – Weld Residual Stresses Modelling

Weld cross section:

- geometry

- bead size and numbers

Weld residual stresses simulation:

- thermal and mechanical analyses

- axial stress

- areas in compression and in tension

Material has experienced:

- heating and cooling

- compression and tension

- plastic strains

8 2016-09-28

Outline

9

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

2016-09-28

Pressure Vessel – Analysis description

10

Bending downwards

Bending upwards

As welded

2016-09-28

Pressure Vessel – Results

11

Bending only

Hoop stress: -205 MPa -> 200 MPa

Welding only

Hoop stress: -301 MPa -> 421 MPa

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Pressure Vessel – Results: bending followed by welding

12

Bending Downwards: Hoop stress: -305 MPa -> 421 MPa

Bending Upwards: Hoop stress: -299 MPa -> 421 MPa

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Pressure vessel – Results: welding followed by bending

13

Bending Downwards: Hoop stress: -197 MPa -> 195 MPa

Bending Upwards: Hoop stress: -218 MPa -> 219 MPa

2016-09-28

Outline

14

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

2016-09-28

Core Shroud Support – Set up and Model

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Core Shroud Support – Final Results

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Simulation result - field plot

Deep hole drilling measurement

Path plots

Core Shroud Support – Post Weld Heat Treatment

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• 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

Before Post Weld Heat Treatment After Post Weld Heat Treatment

Outline

18

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

2016-09-28

Support plate – root failure

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Support plate – Post Weld Heat Treatment

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Conclusions

21

• 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.

2016-09-28

Thank you for your attention!

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