Welding and Heat Treatment in Steel industry

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Leonard French
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Welding and Heat Treatment in Steel industry Modeling Techniques and Applications

4 Thermal & MetallurgicalProperties Thermal properties versus to temperature (T c) and according to the considered phases (z i ) Thermal conductivity : = f(t c, z i ) Density : = f(t c, z i ) Specific heat : C p = f(t c, z i ) Enthalpy : H = f(t c, z i ) Latent Heat Effect : H = f(t c, z i ) Metallurgical Kinetics of Transformation for different heating and cooling rate Austenitic Transformation : Z = f(t c, dt/dt) Ferrite Transformation : Z f = f(t c, dt/dt) Bainite Transformation : Z b = f(t c, dt/dt) Martensite Transformation : Z m = f(t c) Copyright ESI Group, All rights reserved.

5 Déformation [%] MODELISATION CCT Diagram Transformations de phase (acier) Evolution d état Yield Stress vs Temperature for each phases. 1,6 Austenite Transformation 1,2 Phase Face-centered 0,8 0,4 Body-centered cubic Phase cubic Cooling Rate dt/dt = -15 C/s 0 Martensite Transformation -0, Température [ C] Copyright ESI Group, All rights reserved.

6 Mechanical Properties Mechanical properties versus to temperature (T c) and according to the considered phases (z i ) Young s modulus : E = f(t c, z i ) Poisson coefficient : = f(t c, z i ) Thermal strains : th = f(t c, z i ) Yield stress : = f(t c, z i ) Strain hardening : h = f(t c, z i ) Viscous parameter Hardening Coefficient : K = f(t c, z i ) Hardening Exponent : m = f(t c, z i ) Strain Rate Sensitive Exponent : n = f(t c, z i ) Copyright ESI Group, All rights reserved.

7 MODELES PHYSIQUE SYSWELD permet un couplage fort entre la Thermique et la Métallurgie Electromagnétisme Dissipated Joule Energy Temperatures Analyse Thermique Latent Heat Temperatures Phase Proportions Metallurgie Temperatures Chemical Composition Precipitations Deformationenergy Stresses Temperatures Phase Proportions Diffusion - Précipitations Analyses Mécaniques Chemical Composition Precipitations Copyright ESI Group, All rights reserved.

Nozzle HyperQuench Objectives: Residual stresses and deformation after treament,

Nozzle repair Residual stress analysis Multi pass welding: Thermal

of the 30 welding pass taking into account convection and

Goldak heat source Drain/ Instrumentation Nozzle Realistic

20 Nozzle repair Residual stress analysis Multi pass welding: Thermal /metallurgical /mechanical analysis Thermal analysis during each of the 30 welding pass taking into account convection and radiation Stress analysis during welding sequences Predifined Goldak heat source Drain/ Instrumentation Nozzle Realistic as-built model SYSWELD Courtesy Doosan Copyright ESI Group, All rights reserved. 20

21 Nozzle repair Residual stress analysis Heat treatment: Heat convection and radiation Stress released after Post Weld Heat Treatment (PWHT) SYSWELD Courtesy Doosan Copyright ESI Group, All rights reserved. 21

CTC Examples & proofs from ship building (CTC) & railway (Maglev) Original position Measured distortion Predicted distortion Tool bars Output Console

24 CTC Examples & proofs from ship building (CTC) & railway (Maglev) Original position Measured distortion Predicted distortion Tool bars Output Console Distorted Structure SYSWELD Predictions Validation Plot Example of Shipbuilding Application (Courtesy CTC) 24 Copyright ESI Group, All rights reserved. 24

Transient Welding Modeling Multi-Pass Welding

ITER Vacuum Vessel Welding ITER project Vacuum

the inner and outer shell Machining the housing

vessel SYSWELD Welding the components together

30 ITER Vacuum Vessel Welding ITER project Vacuum vessel electron beam welding assembly Rolling the inner and outer shell Machining the housing holes 1 of the 9 sectors of the ITER vacuum vessel SYSWELD Welding the components together VEC mock-up Copyright ESI Group, All rights reserved. 31

Cold cracking Welding of a Dissimilar weld Electron beam process Case study : 26 months in storage conditions Pressure test Hydrogen diffusion Crack

41 Cold cracking Welding of a Dissimilar weld Electron beam process Case study : 26 months in storage conditions Pressure test Hydrogen diffusion Crack initiation and propagation 3 Materials + molten zone MATERIAL_2 Initial H content MATERIAL_1 MATERIAL_3 Copyright ESI Group, All rights reserved. 42

Welding simulation 3D axial symmetric model By Steady state method on 340 degrees By a

on Température and Plastic Strains Initial H2 content

45 Hydrogen diffusion Iso H2 concentration after welding and 1 during year storage Hydrogen concentration H2 properties depend on Température and Plastic Strains Initial H2 content Cumulative plastic strain Copyright ESI Group, All rights reserved. 46

Cumulative plastic strains Hoop stresses Crack

propagates under the effect of welding residual stresses

5 mm where J = Jmax along the front H2 a Plastic strains

46 Cumulative plastic strains Hoop stresses Crack propagation 26 months In storage conditions Crack propagates under the effect of welding residual stresses and hydrogen embrittlement J H1 a = 0 if J Jc kj/m² a = 0.5 mm where J = Jmax along the front H2 a Plastic strains developed at the crack front Copyright ESI Group, All rights reserved. 47

47 Crack propagation In storage conditions Crack propagates under the effect of welding residual stresses and hydrogen embrittlement Compressive hoop stresses Decreasing tensile hoop stresses From 0 to 26 months Copyright ESI Group, All rights reserved. 48

Conclusions Delivered Value Couple mechanical results and hydrogen diffusion to capture the crack propagation kinetic Requires a better characterization of H

singularity Possibility to check the stability of an open crack Simulation of the pressure test with a crack open Simulate the same crack behavior in real flight

49 Conclusions Delivered Value Couple mechanical results and hydrogen diffusion to capture the crack propagation kinetic Requires a better characterization of H diffusion to consider trapping effect 3D modeling of H diffusion and averaging of values in the first ring of elements could be done in order to smooth numerical singularity Possibility to check the stability of an open crack Simulation of the pressure test with a crack open Simulate the same crack behavior in real flight conditions Requires the definition of flight loads Do not require any new material characterization as the crack tip is out of the HAZ Copyright ESI Group, All rights reserved. 50

50 Thank You You Product, processes, knowledge, engineering Simulation Helps to improve engineering You & Simulation Engineering Cost reduction & Quality improvement Simulation makes engineering more transparent Copyright ESI Group, All rights reserved. 51

SYSWELD Complete Finite Element Solution for Simulation of Welding Processes. Josef Tejc MECAS ESI s.r.o., CZ

SYSWELD Complete Finite Element Solution for Simulation of Welding Processes Josef Tejc MECAS ESI s.r.o., CZ Company introduction Uslavska 10, Pilsen Czech Republic e-mail: info@mecasesi.cz web-page: http://www.mecasesi.cz