Neda HASHEMI Gaëtan GILLES Rúben António TOMÉ JARDIN Hoang Hoang Son TRAN Raoul CARRUS Anne Marie HABRAKEN 2D Thermal model of powder injection laser cladding of high speed steels (HSS) 23 oct

Bhattacharya & al. Mater. Sci. Eng. A, (2011) Introduction - Laser cladding (LC) 2 Innovative technology Production of dense parts Multilayer metal deposit Very high cooling rates (ultrafine grain microstructure) Sirris

Problems Heat accumulation during the deposition process:  Variation of layers height as a function of thermal history at each point of the part Need of a thermal model:  Study of processing parameters: laser power powder flow preheating temperature (T°) laser beam velocity  Aim to produce a coating with a constant height layer and constant melt pool J.Tchuindjang. et al. Convention RW RECYLCLAD Thick and narrow coating - block from high speed steel (hss) Introduction – Aims of the research 3 Last layer Apparent layer

4 Content Introduction Experimental study Experimental study 2 types of deposit 2 types of deposit Average layers height Average layers height Effect of processing parameters Effect of processing parameters 2D Thermal model Adjustment and assumptions Results Flux Calibration between 2D and 3D Summary Prospect

PowderCMn Cr Mo VWCoNiSiFe HSS A Balance HSS B Balance Deposit A Deposit B Microstructure (SEM) Eutectic M 7 C 3 (Rich in Cr) Primary angular MC, Primary Clover- shaped MC (Rich in V) Eutectic coral-shaped MC (Rich in V) Eutectic M 2 C (Rich in Mo & W) Cigar-shaped Eutectic MC (Rich in V) Primary angular MC Grain size (about 12 µ) 2 types of deposit – Chemical composition 5

Height of the last cladding layer (H layer ) (top of the deposit) : 2300 µm = 2.3 mm = real cladding layer height Height of apparent cladding layer (h) : 836 µm = mm Number of apparent cladding layers in the last track : Total height of deposit: H deposit = (n experimental layers – n apparent cladding layers ). h + H layer 2.3 mm 0.8 mm Average layers height h= mm 6 Last layer Apparent layer

7 Laser power: Effect of processing parameters (1) Grade Material under the substrate Deposit dimension (mm) P (W) Preheat ing T° (°C) P (mg/s) Speed (mm/ min) Target layer height (mm) h Target total height (mm) H N° of layers (experimental) N=H/h Measured total height by Sirris (mm) HM Obtained apparent layer calculated (mm) A1Insulator30x  A2Insulator30x  Δ power (laser parameter) = 80 W  Δ HM (result) = 3.7 mm on the total height of the deposit HM A1 ˃ HM A2 -- Current apparent layer height of experimentalist = 0.7 (independent of materials and process parameters)

8 Preheating temperature: Grade Material under the substrate Deposit dimension (mm) P (W) Preheat ing T° (°C) P (mg/s) Speed (mm/ min) Target layer height (mm) h Target total height (mm) H N° of layers (experimental) N=H/h Measured total height by Sirris (mm) HM Obtained apparent layer calculated (mm) A3Insulator20x  A4Insulator20x  Effect of processing parameters (2) ΔT°(process parameter) = 50 °C  Δ HM (result) = 1 mm on the total height of the deposit HM A4 ˃ HM A3

9 Material used under the substrate: Grade Material under the substrate Deposit dimension (mm) P (W) Preheat ing T° (°C) P (mg/s) Speed (mm/ min) Target layer height (mm) h Target total height (mm) H N° of layers (experimental) N=H/h Measured total height by Sirris (mm) HM Obtained apparent layer calculated (mm) B1Insulator30x  B2 Steel plate 30x  Effect of processing parameters (3) Δ HM (result) = 3.6 mm on the total height of the deposit HM B1 ˃ HM B2 Deposit Substrate Insulator or steel plate Al plate

10 Laser power vs preheating temperature Grade Material under the substrate Deposit dimension (mm) P (W) Preheat ing T° (°C) P (mg/s) Speed (mm/ min) Target layer height (mm) h Target total height (mm) H N° of layers (experimental) N=H/h Measured total height by Sirris (mm) HM Obtained apparent layer calculated (mm) A5 Steel plate 30x  A6 Steel plate 30x  Δ T° (process parameter) = 100 °C Δ power (laser parameter) = 80 W HM A5 ˃ HM A6 Δ HM (result) = 2.1 mm on the total height of the deposit Greater effect of laser power Effect of processing parameters (4) A5: laser power, lower preheating T° A6: laser power, preheating T°

11 Content Introduction Experimental study Average layers height Effect of processing parameters 2D Thermal model 2D Thermal model Adjustment and assumptions Adjustment and assumptions Results Results Flux Calibration between 2D and 3D Flux Calibration between 2D and 3D Summary Prospect

Geometry of laser cladded deposit and substrate 12 Scanning paths in (X, Y) and (X, Z) planes Position of 4 thermocouples in the substrate Substrate Deposit Steel plate Al plate W S E N

L f : Latent heat (J/Kg) C p : Specific heat: (j/kg.K) Ehsan Toyserkani et al. Optics and Lasers in Engineering, 2004 Masoud Alimardani et al. Optics and Lasers in Engineering, Thermal properties of the material: Latent heat of fusion and modified C p Material Melting point temperature Deposit A1245 °C (1518 K)1335 °C (1608 K) Deposit B1230 °C (1503 K)1380 °C (1653 K) Substrate1480 °C (1753 K)1500 °C (1773 K)

Ehsan Toyserkani et al. Optics and Lasers in Engineering, 2004 Masoud Alimardani et al. Optics and Lasers in Engineering, 2007 L. Costa et al, Acta Materialia LONG Ri-sheng et al. Trans, Nanferrous Met, Soc, 2008 F Laser (W/m 2 ) : heat flux = (1-R) Surface absorptivity + … + other leaks (powder excess, effect of argon flow within the powder jet…) to reach the flux actually used to melt the powder 14 Energy distribution - Moving laser beam Laser with cylindrical radiusPower density Power density concentration 1.6 mm X Flux X Constant flux applied in the model Flux model = x F laser FE nodes

Heat dissipation is different between 2D model and real 3D laser cladding process More heat dissipation in real 3D laser cladding during construction of a layer  Lower temperature in real 3D process 15 T° in 2D model vs real 3D process 2D modelReal 3D process 2D model T° > 3D real process T° Need of flux calibration

y x Average height of the last layer H layer = 2.3 mm Value of flux F model = x 10 8 w/m 2 F model is divided by 4.7 to obtain the same H layer in 2D simulation F 2D = x 10 8 w/m 2 16 Calibration of flux

2D mesh for a 5 layer deposit – Boundary conditions Al plate Steel plate Deposit Substrate 195 mm 40 mm 50 mm --- Convection with air 2 Preheating Temperature (T°) of 300 °C ( K) 460 °C ( K) 20 °C ( K) mm

5 Layers deposit 18 B powder Preheating T° of 460 °C

Preheating T° of K K T° Max (K) - A T° Max (K) - B Layer deposit - Comparison between deposits A and B 1st layer 2nd 3rd 4th 5th Substrate Deposit

20 5 Layer deposit - Substrate T° - B Experimental Modeling W S E N N S

To compare 2D with 3D model Application of a single flux F 3D = x 10 8 w/m 2 Search for the flux value in 3D model providing same max temperature than 2D model F 3D = F 2D x 1.17 In 3D there is conduction of flux in a 3 rd direction  F 3D > F 2D 21 Flux Calibration between 2D and 3D

22 Experimental study: Greater deposit layer height & deposit total height by increasing the laser power, preheating T°, and using insulator under the substrate Greater effect of laser power compared to the preheating T° Thermal model: 2d thermal model of 5 layer deposit with a first calibration by dividing the flux by 4.7 the same remelted depth of deposit as in experimental the same range of substrate T° as in experimental Flux calibration between 2D and 3D model highlights more heat dissipation in 3D Able to quantify effects: Preheating T° increase  Increasing T° of the deposits Value of maximal temperature (Liquidus T° material B > material A) Summary

23 Need of more experimental tests to validate the calibration of the model: Thin wall deposit Additional thermocouples on the substrate surface Prospects Lundback-Modelling of metal deposition, 2011

24 Thank you for your attention

25 5 Layers deposit- Substrate T° - B Experimental Modeling Layer 1  2 Layer 3  4 Layer 2  3 Layer 4  5 Z Y One layer d1, …, dn Position of thermocouple

26 5 Layers deposit- Substrate T° - B Experimental Laser is here (X,Y) plane of a layer Experimental - Zoom of the peaks Position of thermocouple d1, …, dn One layer

Ehsan Toyserkani et al, Optics and Lasers in Engineering 41 (2004) 849–867 Masoud Alimardani et al, Optics and Lasers in Engineering 45 (2007) 1115–1130 L. Costa et al, Acta Materialia 53 (2005) 3987–3999 LONG Ri-sheng et al, Trans, Nanferrous Met, Soc, China 18(2008) F Laser (W/m 2 ) : heat flux r: radius from the center of laser beam P (w): Laser power r L (m): Radius of the laser beam (1-R): Surface absorptivity Speed of the laser passage 27 Energy distribution of moving laser beam Cylindrical radius of the laserPower density of the laser Power density concentration 1.6 mm V X Flux X Continuously applied flux over 3 nodes

29 Moving laser on 3D