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Comparison of experimental and simulation distortions of quenched C-ring test parts

12 th ESAFORM 2008 conference on material forming. Enschede, The Netherlands 27, 28 and 29 april 2009. Comparison of experimental and simulation distortions of quenched C-ring test parts. C. NICOLAS, Ph.D. Student C. BAUDOUIN, Assistant-professor R. BIGOT, Professor

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Comparison of experimental and simulation distortions of quenched C-ring test parts

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  1. 12th ESAFORM 2008 conference on material forming Enschede, The Netherlands 27, 28 and 29 april 2009 Comparison of experimental and simulation distortions of quenched C-ring test parts C. NICOLAS, Ph.D. Student C. BAUDOUIN, Assistant-professor R. BIGOT, Professor L. LELEU, Assistant-professor M. TEODORESCU, Research engineer LCFC

  2. Presentation content • Methodology applied to quantify distortions • Introducing C-ring test part • Application of the methodology on C-ring test parts • Conclusion and outlook

  3. Methodology applied to quantify distortions

  4. Introducing C-ring test part Eccentricity Geometry Manufacturing process Heating (930°C) + oil/gas quench (20°C) Machining Stress relieving

  5. C-ring geometry & quench distortions temperature microstructure stress Gradients of 100% martensite 50% ferrite + 45% bainite + 65% bainite + 5% martensite 35% martensite Heterogeneity Distortions CCT diagram Gradients of heating/cooling rate 3 gradients of thickness Radial  Circumferencial  Longitudinal  Pincers extremity 3 Core 2 1 Case (surface)

  6. Experimental data for simulation • Steel grade: thermo-elasto-visco-plastic behaviour • Mechanical data: yield stress, flow stress, hardness, … • Thermal data: dilatation coefficients, conductivity, … • Metallurgical data: TTT/CCT diagram • Process modelling: temperature evolution (thermo couples) • Heating 20° to 930° Thermal law • Quench 930° to 20°C  Thermal law inner/outer cylinders For each metallurgical phase Nominal geometry Simulation sofware: Forge 2008 TTT Distortions & temperatures Distortions & temperatures

  7. Measurement ofreal and simulated parts Upper plane 110 points Right generatrix Outer cylinder 1722 points 21 points 1722 points 21 points 38 points Inner cylinder Left generatrix Bottom plane Measurement meshing • For real parts probing with a CMM overall uncertainty : 1.6 μm • For f.e.m. parts algorithm for virtual probing [1] overall uncertainty : 0.5 μm with 217 500 nodes for a C-ring Same gaps fields for real and virtual C-ring [1] C. Nicolas and al., “Dimensional control strategy and products distortions identification”, International Journal of Material Forming (Springer), vol. 1, pp. 1039-1042, 2008.

  8. Modelling distortion phenomena • Gaps fields analysis for real and simulated C-rings • Significant distortion phenomena • Pincers and gap opening • Barrel/bobbin effect of rear generatrixes • Lip effect of front generatrixes • Height variation Gap generatrixes (topside view) Cylinders (topside and iso views) Planes (left view) Height variation Bobbin effect Barrel effect Lip effect Lip effect Gap opening Pincers opening Quenched geometry of real C-ring Quenched geometry of virtual C-ring Scale factor: x50 Nominal geometry

  9. Modelling distortion phenomena Physical origin Relevance • known  literature • e.g. pincers opening [2] [3] [4] [5] • unknow  experimental and f.e.m. tests • e.g. lip effect • linearity • independence Significant distortion phenomena Choose the mathematical expressions for each one [2]R.A. Hardin and al., “Simulation of Heat Treatment Distortion”, In the Proceedings of: 59th Technical and Operating Conference, Chicago, 2005. [3] Z. Li and al., “Experiment and Simulation of Heat Treatment Results of C-Ring Test Specimen”, In the Proceedings of: 23rd ASM Heat Treating Society Conference, Pittsburgh, pp. 245-252, 2005. [4] D.O. Northwood and al., “Retained austenite - Residual stress - Distortion relationships in carburized SAE 8620 steel”, Materials Science Forum, vol. 539-543, pp. 4464-4469, 2007. [5]B.E. Brooks and al., “Prediction of Heat Treatment Distortion of Cast Steel C-Rings”, In the proceedings of: 61th Technical and Operating Conference, Chicago, 2007.

  10. Modelling distortion phenomena Physical origin • For the two cylinders • Heterogeneity of • cooling rate (faster near pincers) Time-dependent combination between thermal metallurgical and mechanical stresses Heterogeneity of cooling rate inside/outside Unknown  f.e.m. approach needed

  11. Modelling distortion phenomena Physical origin • For the planes and the gap • Volume change Thermo-mechanical stresses • Volume change Thermo-mechanicaland metallurgical stresses Heterogeneity of cooling rate inside/outside

  12. Modelling distortion phenomena Relevance • linearity  mathematical expressions checked • detection of slight dependence  by comparing each phenomena uncertainty to the measurement uncertainty When measuring the real C-ring: measurement uncertainty = 1.6 μm Phenomena uncertainties < measurement uncertainty  no great dependence  distortion phenomena are dissociated by the optimization method

  13. Dissociation of distortion phenoma • One steel grade - 4 cooling rates - 3 C-rings for experiments - 1 for simulation • Amplitudes of distortion phenomena Pincers opening (shape change) Gap opening (volume change) Increase Opening Increase Opening Decrease Closing Gap opening  with cooling rate Gap opening  - simu. - oil quench Pincers opening  with cooling rate Pincers closing - simu. - oil quench Same trends excepted for oil quench Same amplitudes for gap opening (gas quenches)

  14. Dissociation of distortion phenoma Increase Increase Increase Increase • Amplitudes of distortion phenomena Barrel effect of generatrixes Lip effect of generatrixes Increase Decrease Decrease Increase Barrel  with cooling rate in gas quenches Barrel  in oil quench Lip  with cooling rate in gas quenches Lip  in oil quench Symmetry of the two effects inner/outer cylinders Same trends & comparable amplitudes for some cooling rate

  15. Conclusion • Methodology closed to physical origin of distortions • Distortions (volume changes) thermal effect • Gap opening • good agreement exp. & simu. (like in literature) • Origin: volume variation • Height variation • same tendancies exp. & simu. but not the amplitudes • Origin: volume variation • Distortions (shape changes) metallurgical & mechanical effect Same trends exp. & simu. but not the amplitudes • Pincers opening • Origin: combination between cooling rate gradient and steel phase transformations gradient inside pincers • Lip effect • Origin: local effect at the end of pincers, to be determined by simulation • Barrel effect • Origin: heterogeneity of cooling rate inner/outer cylinders

  16. Outlook Quench time End of heating • Investigation via simulation: • chronology of distortions & phases transformations Pincers opening Pincers closing Other distortion phenomena

  17. Outlook • Investigation via simulation: • chronology of distortions & stresses (related with phases transformations) Quench time Barrel effect creation  Start of ferrite  Start of bainite  Start of martensite Compressive stress Tensile stress Lip effect creation

  18. Outlook • Investigation via simulation: • chronology of amplitudes of distortion phenomena Barrel effect Pincers Lip effect opening Critical quench moments  martensite transformation

  19. 12th ESAFORM 2008 conference on material forming Enschede, The Netherlands 27, 28 and 29 april 2009 Comparison of experimental and simulation distortions of quenched C-ring test parts C. NICOLAS, Ph.D. Student Thank you for your attention LCFC

  20. Dissociation of distortion phenoma Shapes modelled with Fourier/Chebyshev functions or eigenfunctions. Goal: to separate effects of elementary distortions amoung the overall deformation • Existing optimization methods: • Modal analysis [6] [7] • Proper Orthogonal Decomposition (POD) [8] • … • Used method in this work [9]: • Vectorial decomposition method • Already successfully applied: • to identify distortions: • on camshaft • on bevel gear obtained by net shape forging • to control geometric position of an hexapod [6] S. Samper and al., “Form Defects Tolerancing by Natural Modes Analysis”, Journal of Computing and Information Science in Engineering, 2007. [7] K.D. Summerhays and al., “Optimizing discrete point sample patterns and measurement data analysis on internal cylindrical surfaces with systematic form deviations”, Precision Engineering, 2002. [8] L. Vanoverberghe and al., “Detection of deviations origins in a heat treatment process using POD basis”, Int. J. of Material Forming, 2008. [9] C. Nicolas and al., « Stratégie de contrôle dimensionnel et identification de la déformation d’un produit - Application à une pièce test traitée thermiquement », In the Proceedings of: Conception et Production Intégrées (CPI), Rabat (Maroc), 2007.

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