Transcript Laser Surface Modification

Laser surface coating of bulk metallic glass
composition on high carbon low alloy steel
A. Basu1*, J. Dutta Majumdar2, N.B. Dahotre3, I. Manna2
1Metallurgical
& Materials Engineering Department, N.I.T., Rourkela Orissa. 769008
2Metallurgical & Materials Engineering Department, I.I.T., Kharagpur, W.B. 721302
3Department of Materials Science and Engineering, University of Tennessee, Knoxville,
TN 37996, USA
*[email protected]
63rd ATM, 16th November, 2009
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]
Evolution of Met-glass/BAAs
Properties of 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)
•
Multi-component alloys
•
(dT/dt)Cr  103 K/s
•
Deep eutectic
-DHM (enthalpy of mixing)
•
•
h (viscosity) > 109 Pa-s at Tg
•
t (str. relax. time) near TMP
T, K
Liquid
Mechanical Properties
Crystal
MG
BAAs
t, s
•High Hardness, Strgth
•High Young Modulus
Systems
Sl.
Year
Substrate/deposit
Laser
Reference
1
1980
Chilled cast iron
Nd: Glass,pulsed
Snezhnoi et al.
2
1980
Cast tool steel /Fe-B (sprayed)
CW-CO2
Bergmann-Mordike
3
1981
Fe-2C-12Cr/Fe-B Nb-alloy
CW-CO2
Bergmann-Mordike
4
1981
Fe-C/Si-P-B (ternary/quaternary)
TEA-CO2 pulsed
Borodona et al.
5
1982
Fe-Fe3B, (modulated thin film)
Nd:YAG, pulsed
Lin-Spaepen
6
1983
Fe-4 at.% B
Nd:YAG, pulsed
Lin-Spaepen
7
1984
Mo/Ni (30-60 at%), Mo/Co (45 at%),
Co/Nb (40 at%)
Nd:YAG, mode
locked
Lin et al.
8
1984
Ni-Nb thin film Zr/Cu
Nd:YAG
Lin-Spaepen
9
1984
Zr/Cu
Nd:YAG, Q-switched
Den Broeder et al.
10
1984
Au- Ti, Co- Ti, Cr- Ti, Zr- Ti
Pulsed
Affolter-von Allmen
11
1984
Pd-6Cu-16Si
CW-CO2
Yoshioka et al.
12
1984
Fe-10Si-15B
Pulsed CO2
Kumagai et al.
13
1985
Fe-10Cr-5Mo/12-14 P, C
CW-CO2
Yoshioka et al.
14
1985
Pure Ga
KrF excimer
Frohlingsdorf et al.
15
1987
Mild steel/Ni-Cr-16P-4B
CW-CO2
Yoshioka et al.
16
1987
Ni, Cu(Ni), Ti(Ni)/Pd-25Rh-10P-9Si
CW-CO2
Kumagai et al.
Sl.
Year
Substrate/deposit
Laser
Reference
17
1988
Nb/Ni-Pt-Pd-Rh
CW-CO2
Kumagai et al.
18
1988
Fe-Cr-P-C-Si
CW-CO2
Gaffet et al.
19
1990
Review-paper
Hashimoto et al.
20
1991
SiC
Knotek and Loffler
21
1995
Cu/PdCuSi
CW-CO2 and Nd:YAG
Wang et al.
22
1997
AI-Si/Ni-WC
Plasma sprayed and laser melted with a CW-CO2 laser
Liang and Wong
23
1997
AI-Si/Ni-Cr-B-Si
Plasma sprayed and laser melted with a CW-O2 laser
Liang and Wong
24
1997
AI-Si/Ni-Cr-AI
Plasma sprayed and laser melted with a CW-CO2 laser
Liang and Wong
25
1997
Al/Zr60Al15Ni25
26
1999
Al alloy/Ni-Cr-Al
CW-CO2
Li et al.
27
1999
Ni-Cr-B-Si-C
CW-CO2
Li et al.
28
1999
Concrete
CW-CO2
Lawrence and Li
29
2000
(Austenitic SS) SiO2
Nd:YAG
Wu and Hong
30
2000
Al alloy/Ni-Cr-B-Si
and Ni-Cr-Bi-WC
CO2
Wong et al.
31
2000
Al alloy/Ni-Cr-Al
CW-CO2
Liang and Su
32
2000
(Austenitic SS) Zr
Pulsed Nd:YAG
Wu and Hong
33
2000
Cu/Al2O3
34
2000
Al-Si/Ni-Cr-Al
CW-CO2
Liang et al.
35
2000
(Fe) Fe57Co8Ni8Zr8
CW-CO2
Wu and Hong
36
2001
Fe57Co8Ni8Zr10Si4B13
Carvalhoa et al.
Shepeleva et al.
Xiaolei and Youshi
SUBSTRATE : SAE 52100
Element
C
Si
Mn
Cr
Fe
Wt %
0.95 – 1.05
0.15 – 0.35
0.29 – 0.40
1.50 – 1.65
Rest
Equivalent grades AISI 52100 (USA), EN 31 (UK), SUJ 2 (Japan), DIN 100Cr6
(Germany) BS:2S135/535A99 (British), AFNOR:100C6 (France) IS 104Cr6 (India)
Spheroidized annealed
PROCESS : LASER COATING
Due to possible high cooling rate (~ 106 K/s)
EXPERIMENTAL
Laser Parameters:
Laser: 2.5 kW Nd:Yag
Beam size: 3 mm X 600 μm
Power density: 1.39 kW/mm2
Overlap: ~ 15%
Condition: Defocused by 0.5 mm
Clad material: Fe48Cr15Mo14Y2C15B6k
Power: 1.5 and 2.0 kW
Scan speed: 2.5 and 3.5 m/min
Scan type: Single and double (perpendicular to the first)
XRD and DSC of PRE-COATED POWDER
XRD of Fe48Cr15Mo14Y2C15B6 powder shows a characteristic diffuse halo
DSC scan of Fe48Cr15Mo14Y2C15B6 at 200C/min. Arrow marks the Tg
PHASE EVOLUTION STUDY by XRD
Laser power: 1.5 kW power
Scan speed: 350 cm/min
Type: double scan
Amount of Fe7C 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
• Two distinguished zone
• Significant grain coarsening
when lased at a higher power.
Laser power: 2.0 kW
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
Test load: 4 kg
Speed: 2.5 mm/s
• Significant
improvement in
wear resistance
was achieved
• Kinetics of wear
varies with laser
parameters.
Ball-on-Plate Wear
Tester
2.5 m/min
3.5 m/min
DEPTH WISE SEM
Laser power: 2.0 kW, Scan speed: 350 cm/min, scan type: double
Magnified
Surface
Magnified
Below surface
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.
THERMAL PROFILE MODELLING
At the surface of the sample, the heat balance between the laser energy absorbed by the
sample and the radiation losses :



 T ( x, y,0,t ) T ( x, y,0,t ) T ( x, y,0,t ) 

-K 


 AI - T ( x,



x
y
z


 1
for 0  t  t
p
and
 0
for t t

4
4
y, 0, t ) -T 
0 
p
A = absorptivity, I = laser power intensity, ε = emissivity of thermal radiation, tp = irradiation timeT0 = ambient temperature
σ = Stefan-Boltzman constant (5.67 × 10-8 W/m2K4)
Convective boundary condition at the bottom surface of the sample is given by:


 T ( x, y, L,t ) T ( x, y, L, t ) T ( x, y, L, t ) 

-K 


 hT ( x,



x
y
z


y, L, t )-T 
0
h = convective heat transfer coefficient, k = thermal conductivity, L = sample thickness
• Melting is of amorphous clad precursor only.
• Latent heat of formation of borides, carbides etc, are negligible.
Thermal profile on top surface
SUMMARY
 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