Presentation on theme: "Laser surface coating of bulk metallic glass composition on high carbon low alloy steel 63 rd ATM, 16 th November, 2009 A. Basu 1*, J. Dutta Majumdar 2,"— Presentation transcript:
Laser surface coating of bulk metallic glass composition on high carbon low alloy steel 63 rd ATM, 16 th November, 2009 A. Basu 1*, J. Dutta Majumdar 2, N.B. Dahotre 3, I. Manna 2 1 Metallurgical & Materials Engineering Department, N.I.T., Rourkela Orissa Metallurgical & Materials Engineering Department, I.I.T., Kharagpur, W.B Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA
Bulk Amorphous Alloy Met-glass is a supercooled liquid with no long-range periodicity and possessing near-theoretical strength, large elastic deformation, high hardness, excellent wear resistance [Klement, Willens, Duwez, Nature, 1960] Properties of BAAs Multi-component alloys dT/dt) Cr 10 3 K/s Deep eutectic H M (enthalpy of mixing) (viscosity) > 10 9 Pa-s at T g (str. relax. time) near T MP Evolution of Met-glass/BAAs Klement et al., Nature (1960) Inoue et al., J. Mater. Sci. Lett. (1987) Masumoto et al. Jpn.J. Appl.Phy. (1988) Inoue et al., Mater. Trans JIM (1991) Peker, Johnson, Appl. Phy. Lett. (1993) Crystal Liquid MG BAAs t, s T, K Mechanical Properties High Hardness, Strgth High Young Modulus
Systems Sl.YearSubstrate/depositLaserReference 11980Chilled cast ironNd: Glass,pulsedSnezhnoi et al Cast tool steel /Fe-B (sprayed)CW-CO 2 Bergmann-Mordike 31981Fe-2C-12Cr/Fe-B Nb-alloyCW-CO 2 Bergmann-Mordike 41981Fe-C/Si-P-B (ternary/quaternary)TEA-CO 2 pulsedBorodona et al Fe-Fe3B, (modulated thin film)Nd:YAG, pulsedLin-Spaepen 61983Fe-4 at.% BNd:YAG, pulsedLin-Spaepen 71984Mo/Ni (30-60 at%), Mo/Co (45 at%), Co/Nb (40 at%) Nd:YAG, mode locked Lin et al Ni-Nb thin film Zr/CuNd:YAGLin-Spaepen 91984Zr/CuNd:YAG, Q-switchedDen Broeder et al Au- Ti, Co- Ti, Cr- Ti, Zr- TiPulsedAffolter-von Allmen Pd-6Cu-16SiCW-CO 2 Yoshioka et al Fe-10Si-15BPulsed CO 2 Kumagai et al Fe-10Cr-5Mo/12-14 P, CCW-CO 2 Yoshioka et al Pure GaKrF excimerFrohlingsdorf et al Mild steel/Ni-Cr-16P-4BCW-CO 2 Yoshioka et al Ni, Cu(Ni), Ti(Ni)/Pd-25Rh-10P-9SiCW-CO 2 Kumagai et al.
Sl.YearSubstrate/depositLaserReference Nb/Ni-Pt-Pd-RhCW-CO 2 Kumagai et al Fe-Cr-P-C-SiCW-CO 2 Gaffet et al Review-paperHashimoto et al SiCKnotek and Loffler Cu/PdCuSiCW-CO 2 and Nd:YAGWang et al AI-Si/Ni-WCPlasma sprayed and laser melted with a CW-CO 2 laserLiang and Wong AI-Si/Ni-Cr-B-SiPlasma sprayed and laser melted with a CW-O 2 laserLiang and Wong AI-Si/Ni-Cr-AIPlasma sprayed and laser melted with a CW-CO 2 laserLiang and Wong Al/Zr 60 Al 15 Ni 25 Carvalhoa et al Al alloy/Ni-Cr-AlCW-CO 2 Li et al Ni-Cr-B-Si-CCW-CO 2 Li et al ConcreteCW-CO 2 Lawrence and Li (Austenitic SS) SiO 2 Nd:YAGWu and Hong Al alloy/Ni-Cr-B-Si and Ni-Cr-Bi-WC CO 2 Wong et al Al alloy/Ni-Cr-AlCW-CO 2 Liang and Su (Austenitic SS) ZrPulsed Nd:YAGWu and Hong Cu/Al 2 O 3 Shepeleva et al Al-Si/Ni-Cr-AlCW-CO 2 Liang et al (Fe) Fe 57 Co 8 Ni 8 Zr 8 CW-CO 2 Wu and Hong Fe 57 Co 8 Ni 8 Zr 10 Si 4 B 13 Xiaolei and Youshi
SUBSTRATE : SAE Equivalent grades AISI (USA), EN 31 (UK), SUJ 2 (Japan), DIN 100Cr6 (Germany) BS:2S135/535A99 (British), AFNOR:100C6 (France) IS 104Cr6 (India)ElementCSiMnCrFe Wt % 0.95 – – – – 1.65 Rest Spheroidized annealed PROCESS : LASER COATING Due to possible high cooling rate (~ 10 6 K/s)
EXPERIMENTAL Laser: 2.5 kW Nd:YagBeam size: 3 mm X 600 μm Power density: 1.39 kW/mm 2 Overlap: ~ 15% Condition: Defocused by 0.5 mmClad material: Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6k Power: 1.5 and 2.0 kWScan speed: 2.5 and 3.5 m/min Scan type: Single and double (perpendicular to the first) Laser Parameters:
XRD of Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 powder shows a characteristic diffuse halo DSC scan of Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 at 20 0 C/min. Arrow marks the T g XRD and DSC of PRE-COATED POWDER
PHASE EVOLUTION STUDY by XRD Laser power: 1.5 kW power Scan speed: 350 cm/min Type: double scan Amount of Fe 7 C decreases with increase in applied power, scan speed or multiple scan
SEM and OPTICAL MICROGRAPH (CROSS SECTION) Scan speed: 250 cm/min, scan type: single Laser power: 1.5 kW Laser power: 2.0 kW Two distinguished zone Significant grain coarsening when lased at a higher power.
SURFACE MECHANICAL PROPERTY: MICROHARDNESS 4 times improvement of base hardness Gradual decrease in hardness profile With increase in scan speed, surface hardness increases and depth of hardened surface zone decreases.
WEAR Ball-on-Plate Wear Tester Test load: 4 kg Speed: 2.5 mm/s Significant improvement in wear resistance was achieved Kinetics of wear varies with laser parameters. 2.5 m/min3.5 m/min
DEPTH WISE SEM Laser power: 2.0 kW, Scan speed: 350 cm/min, scan type: double Surface Below surface Magnified Away from the surface, the precipitates at the grain boundaries/interdendritic regions is less.
DEPTH WISE XRD and WEAR Carbide content is most on the surface and decrease slowly towards substrate as solidification starts near to the substrate. Wear resistance is more at surface layer due to presence of more amounts of hard phases like carbides.
A = absorptivity, I = laser power intensity, ε = emissivity of thermal radiation, tp = irradiation timeT 0 = ambient temperature σ = Stefan-Boltzman constant (5.67 × 10-8 W/m 2 K 4 ) Convective boundary condition at the bottom surface of the sample is given by: THERMAL PROFILE MODELLING h = convective heat transfer coefficient, k = thermal conductivity, L = sample thickness At the surface of the sample, the heat balance between the laser energy absorbed by the sample and the radiation losses : Melting is of amorphous clad precursor only. Latent heat of formation of borides, carbides etc, are negligible. and Thermal profile on top surface
Attempt to develop amorphous coating by LSC not yet successful A defect free clad layer/coating with 250 to 600 mm thickness Cellular/dendritic microstructure Microhardness improved to as high as 950 VHN as compared to 240 VHN of the substrate Significant improvement in wear resistance. Compressive residual stress in the clad layer/coating Failure attributed to compositional changes and not due to lack of required quenching SUMMARY