introduction in welding and heat treatment · pdf file3 specific features of welding and heat...
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Dr.-Ing. Tobias LooseIngenieurbüro Tobias Loose, Herdweg 13, D- 75045 Wö[email protected] www.tl-ing.eu
Introduction in
Welding and Heat Treatment SimulationApplication Fields and Benefits
Workshop Welding and Heat Treatment with LS-DYNA on the
10. European LS-DYNA Conference 2015 Würzburg
Foto: ISF
Herdweg 13, D-75045 Wössingen Lkr. KarlsruheE-Post: [email protected] Web: ww.tl-ing.eu, www.loose.at
Mobil: +49 (0) 176 6126 8671 Tel: +49 (0) 7203 329 023 Fax: +49 (0) 7203 329 025
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Numerical Simulation forWelding and Heat Treatment since 2004
• Consulting• Training • Support• Software Development• Software Distribution
for Welding Simulation and Heat Treatment Simulation
Herdweg 13, D-75045 Wössingen Lkr. KarlsruheE-Post: [email protected] Web: www.tl-ing.eu www.loose.at
Mobil: +49 (0) 176 6126 8671 Tel: +49 (0) 7203 329 023 Fax: +49 (0) 7203 329 025
Internet:DEeutsch: www.loose.atENglisch: www.tl-ing.euESpanol: www.loose.es
www.WeldWare.eu
www.SimWeld.eu
www.DynaWeld.eu
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Specific Features of Welding and Heat Treatment Simulation
Material Properties– material properties depend on temperature– material properties change in thermal loading cycles
→ change of microstructure / phase transformation
History Variables– stress, strain, strain hardening– phase proportion
Material Modell– reset of material history– phase transformation– phase transformation effects
Time Schedule– History of events
in order of time
MaterialSimulation
Process Simulation
Structure Simulation
Welding & HTSimulation
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Properties of the WeldMicrostructure - mechanical Properties
www.weldware.eu
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Prediction of Microstructure
Prediction of microstructure in the HAZin dependence of steel grade and its chemical composition
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Prediction of the estimated mechanical Properties in the HAZ...
• Hardness• Yield stress• Ultimate stress• Ultimate strain• Brucheinschnürung
… to avoide technological kerbs in comparison to the unwelded
base material.
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Simulation at Mikro-NiveauSolidification, Graingrowth, Phase Transformation
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Welding Process AnalysisParameter Adjustment for GMAWEquivalent Heat Source
www.simweld.eu
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SimWeld Preprocessing
• Definition of:– wire: feed, diameter, material,– stick out– travel speed– angle of torch, stabbing, slabbing, skew– shielding gas– machine settings U, I– process type normal, pulsed U/I, pulsed I/I– pulse parameter
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• Equivalent Heat Source• Weld Pool Geometry• Droplet• Wire Temperature• Energy, Voltage, Currency• Temperature Curve
SimWeld Results
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Welding Structure AnalysisResidual Stress - Distortion - Temperaturein the whole Assembly
DynaWeld
www.dynaweld.eu
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Welding Structure Analysis Using the Finite Element Method
Geometry of the Assembly - CAD
Method of the Finite Elements
FEM
Discretisation in Finte ElementsMeshing
WeldingAdjustment of equivalent Heat Source
Materials Material Properties
Process and Time ScheduleWeld Sequence, Material Assignment,
Clamps, Loads
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The most important Items of the Welding Structure Analysis
• Geometry• Material
– dependend of Temperature– Strain Hardening
• Reset of Strain Hardening at Melting Point– Phase Transformation
• Transformation Strain• material properties depend on microstructure
and phase transformation
• Heat Source– Geometry and equivalent Heat Source Funktion– Trajectory and Travel Speed
• Mechanical Boundary Condition– Clamps– Contact
• Results– Deformation– Residual Stress, Strain, Yield Stress– global Temperature Distribution and Microstructure
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Phase Transformation and Transformation Effects
ferritic grid krz → austinitic grid kfzVolume change during phase transformation
right: Animation of thermal strain and transformation strain during the heating an colling at different cooling rates (S355)bottom right:Transformation and Dilatation (1.4317)bottom left: Phase-Cooling-Rate -Diagram S500 comparison of given data and simulaion
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Process Types
• Fusion Welding – Arc– Arc Welding
– Gas Metal Arc Welding
– Submerged Arc Welding
– Tungsten Inert Gas Welding
• Electro-Resistand Welding– Spot Welding
• Friction Welding– Rotational Friction Welding
– Orbital Friction Welding
– Friction Stir Welding
• Fusion Welding – Beam– Laser Welding
– Electron Beam Welding
Welding Structure Analysis with
Equivalent Heat Source
Special Analysisfor Welding Process
EM, FEM, EFG, SPH
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Equivalent Heat Source
• The Equivalent Heat Source is a coupled function of geometry and intension of the heat generation density.
• It describes the thermal loading of a welding structure simulation.• Its aproach is to generate the same heat input as the real proccess.• It is an engineering aproach and not real physics.• It covers fluid dynamic effects like convection in the weld pool.• Any funktion is allowed.• SimWeld can predict the heat source parameter for GMAW.
Foto: ISF
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Validation
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• Plate with the dimension270 x 200 x 30 mm3 with V/U-shaped groove
• austenitic stainless steel (316LNSPH, kf = 275 MPa)
• 2 Layer, Filler materials is the same as the base material: 316L
• TIG Welding with U = 9 V, I = 155 A, v = 0,67 mm/s
ValidationIIW Round Robin Versuch
Comparison Measurement and Simulation
Loose, T. ; Sakkiettibutra, J. ; Wohlfahrt, H. : New 3D-Calculations of residual stresses consistent with measured results of the
IIW Round Robin Programme. In: Cherjak, H. (Ed.) ; Enzinger, N. (Ed.) :
Mathematical Modelling of Weld Phenomena Bd. 9, Verlag der Technischen Universität Graz, 2010
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Welding direction
ValidationIIW Round Robin Versuch
SYSWELD
LS-DYNA
Lateral residual stress Longitudinal residual stress
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Temperature – Equivalent StressLateral Residual Stress - Longitudinal Residual Stress
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Validation Nitschke-Pagel Test
Distortion w:Experiment: 0,34 mmSysweld: 0,32 mmLS-DYNA: 0,34 mm
Loose, T.: Einfluß des transienten Schweißvorganges auf Verzug, Eigenspannungen und Stabiltiätsverhalten axial gedrückter Kreiszylinderschalenaus Stahl, Diss, Karlsruhe, 2008
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Welding of a T-Joint
• Double sided T-Joint a = 4 mm• Plate S355 thickness 8 mm• 3 Tacks double sided • Travel speed 80 cm/min• Current: 390 A• Voltage: 30 V
• Start Time Tack 1: 0 s• Start Time Tack 2: 20 s• Start Time Weld 1: 1000 s• Start Time Weld 2: 1023 s• Weld 1 and Weld 2 have
the same travel direction Foto: Volvo
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Process Simulation with SimWeld
Input-Parameter SimWeld
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SimWeld Results
• a = 4,4 mm• I = 390 A• V = 29,2 V
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Temperature
Tack 1 Tack 2
Weld 1 Weld 2
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z-Distortion at Evaluation Pathtransformed to flat left side
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Multi LayeredWelds
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Weld of a Pipe with 40 mm Wall Thicknessmade of Alloy 625
60 Layer - GMAW 93 Layer - TIG
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Weld of a Pipe with 40 mm Wall Thicknessmade of Alloy 625 - 60 Layer GMAW
Temperature Layer 44 Equivalent Plastic Strain
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2D plain strainPlate: 300 x 80 mmStiffner: 150 x 24 mmFillet Weld: a = 13 mmMaterial: 1.4301
Tack Weld a = 1,4 mm With failure criterion strain:KFAIL = 0,25 m/m
Initial gap between stiffner and plate: 0,1 mm
The plate is fixed with symmetry boundary conditions on the left and right side.
Angular Distortion of multilayered Welds2D-Modell LS-DYNA - Simulationsmodell
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Example Angular Distortion of multilayered Welds2D-Model LS-DYNA - Temperaturefield
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Example Angular Distortion of multilayered Welds2D-Modell LS-DYNA – plastische Dehnungen
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Heat Treatment Simulation
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Types of Heat TreatmentProcess steps
• Heating– Austinitsation– grain size– heat generation by induction
• Carburization– change of material– change of composition
• External Pressure– phase transformation
influenced by stress
• Quenching– phase transformation
influenced by thermal cycle
• Tempering / Anealing– smoothing of Martensit / Bainit– stress release
Case Hardening
Quenching
Press Hardening
Induction Hardening
AnenalingPost Weld Heat Treatment
Tempering
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Quenching of a Gear made of S355Temperature – 20 times scaled displacement
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Quenching of a Gear made of S355Martensit - 20 times scaled displacement
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Quenching of a Gear made of S355Temperature – Surface and mid-cross-section
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Quenching of a Gear made of S355Temperature Curve
EdgeMiddle
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Martensit (right)
Hardness HV (bottom left)
Yield (bottom right)
Quenching of a Gear made of S355Results of Heat Treatment Simulation
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Process ChainFormingWeldingHeat Treatment
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Simulation of the Process Chain
MaterialSimulation
Process Simulation
Structure Simulation
Welding & HTSimulation
Forming
CrashClamping and Predeformation
Cutting andGrinding
Assembly
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Deep-Drawing of a Cup from a Laser Welded SheetTask and Model
Welding:• Two sheets (S355) with 1 mm wall thickness are laser weldedForming:• The welded and distorted sheet is
clamped• a globular die is pressed slow in the
sheet.
Model:• Shell-elements are used for the sheet, solid elements are used for the clamps and the die• Same material model (*MAT_244) is used in all steps• History variables, phase proportions and deformations are kept from one step to an other• Welding: implicit analysis, Forming / Crash: explicit analysis
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Stresses and Strains in Midsurface of Shell
After welding and coolingtop left: Longitudinal stresstop right: Effectiv stress (v. Mises)bottom right: plastic strain
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Microstructure
After welding and coolingtop left: Ferrit proportiontop right: Bainit proportionbottom right: Martensit proportion
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Deep drawing – effectiv stress
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Stresses and Strains in Midsurface of Shell
top left: effectiv stress bevor unclamping 200 .. 1100 N/mm²
bottom left: effectiv stess after unclamping 0 .. 200 N/mm²
bottom right: plastic strain after unclamping 0 .. 0.65 m/m
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Microstructure during Deep-Drawing
top left: Ferrit proportiontop right: Bainit proportionbottom right: Martensit proportion
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Thinning of the SheetInfluence of Material Property Change from Welding
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Manufacturing of a BoxTask and Model
Forming:• The roof geometry is made by forming a 3 mm thick sheet (1.4301)Assembly:• Add the sidewallWelding:• Weld the sidewall to the roofClamp and predeformation:• press the sidewall on measureAssembly:• Add the bottom plateWelding:• Weld the bottom plate to the sidewallUnclampingModel:• Solid-element model• Material model (*MAT_270) is used in all steps• History variables and deformations are kept from one step to an other• Implicit analysis in all steps
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Benefit of a Continous Simulation of Process Chain
• Precalcualtion of the final state of the assembly:– geometry
– residual stresses
– microstructure
• Complete simulation of the entire manufacturing process• Take into account the two way impact of single manufacturing tasks
• Enables the design of the manufacturing process• Enables the desing of compensation methods for requested conditions
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Thanks for your Attention!