Outline:  

• Introduction 

• Process Experimental Setup 

• Experimental Procedure 

• Experimental Results for Al2024-T351 and Ti6Al4V 

 - Residual stresses 

 - Tensile Strength 

 - Fatigue Life 

• Discussion and Outlook 

 - Prospects for technological applications of LS

Correa Guinea, Carlos

Diaz Muñoz, Marcos

Gil Santos, Andrea

Morales Furió, Miguel

Ocaña Moreno, José Luis

Porro González, Juan Antonio

Ruiz de Lara de Luis, Leonardo

Archivo Digital UPM

Application of high-intensity short-pulse lasers to the mechanical and surface properties improvement of high reliability metallic components by shock processing

Servicio de Coordinación de Bibliotecas de la Universidad Politécnica de Madrid

1 
Application of High-Intensity Short-Pulse Lasers to the 
Mechanical and Surface Properties Improvement of High 
Reliability Metallic Components by Shock Processing 
 
 
 
J.L. Ocaña, J.A. Porro, M. Morales, M. Díaz, 
L. Ruiz de Lara, C. Correa, A. Gil-Santos 
 
Centro Láser UPM. 
Universidad Politécnica de Madrid. 
Campus Sur UPM. Ctra. de Valencia, km. 7.3. 28031 Madrid. SPAIN 
email: jlocana@etsii.upm.es 
 
  
2 
Application of High-Intensity Short-Pulse Lasers to the Mechanical 
and Surface Properties Improvement of High Reliability Metallic 
Components by Shock Processing 
OUTLINE: 
 
 
• Introduction 
• Process Experimental Setup 
• Experimental Procedure 
• Experimental Results for Al2024-T351 and Ti6Al4V 
 - Residual stresses 
 - Tensile Strength 
 - Fatigue Life  
• Discussion and Outlook 
 - Prospects for technological applications of LSP 
3 
 INTRODUCTION 
 
§ Laser Shock Processing (LSP) is being increasingly applied as a technique 
allowing the effective induction of residual stresses fields in metallic materials 
allowing a high degree of surface material protection against fatigue crack 
propagation, abrasive wear, chemical corrosion and other failure conditions, 
what makes the technique specially suitable and competitive with presently 
use techniques for the treatment of heavy duty components in the 
aeronautical, nuclear and automotive industries. 
 
§ According to the inherent difficulty for the prediction of the shock waves 
generation (plasma) and evolution in treated materials, the practical 
implementation of LSP processes needs an effective predictive assessment 
capability coupled to a readily controllable experimental setup for a correct 
application of treatment parameters and an associate material properties 
characterization capability. 
 
§ In the present communication, the practical LSP treatment and associate 
specimens characterization capabilities developed at CLUPM (Spain) are 
presented along with selected results obtained in several relevant aerospace 
and nuclear industry alloys. 
 
4 
REMINDER OF LSP PHYSICAL PRINCIPLES (1/2) 
5 
REMINDER OF LSP PHYSICAL PRINCIPLES (2/2) 
PROCESS EXPERIMENTAL SETUP 
t = 10 ns;  f = 10 Hz
Q-SWITCHED Nd:YAG LASER
î
í
ì
==
==
J/pulse 1,4E    ; nm 532λ
J/pulse 2,5E  ; nm 1064λ
PROCESS EXPERIMENTAL SETUP 
PROCESS EXPERIMENTAL SETUP 
PROCESS EXPERIMENTAL SETUP 
1 9
17 25
EXPERIMENTAL PROCEDURE 
11 
2d
1
xy
d
y
d
x
Δs
Δy
y
Δx
x
surfacetreated Total
pulsesofNºEOD
Density
gOverlappin
Equivalent
====º
2d
EE
xy
d
y
d
x
E
Δs
Δy
y
Δx
x
surfacetreated Total
Energy Pulse pulsesofNºEED
Density
Energy
Equivalent
===
×
=º
2
d4
π
2d
2 
4
π
surface treated Total
 AreaPulse pulses of Nº
ELOF 
factor goverlappin
local Equivalent
÷
ø
ö
ç
è
æ==
×
=º
ff
EXPERIMENTAL PROCEDURE 
EXPERIMENTAL PROCEDURE 
Residual Stresses (According to ASTM E837-08) 
EA-XX-062RE-120CEA-XX-062UM-120
EXPERIMENTAL RESULTS 
Residual Stresses (According to ASTM E837-08) 
Al2024-T351 Ti6Al4V 
Relatively broad difference between 
Smax and Smin in Al2024-T351 
Relatively small difference between 
Smax and Smin in Ti6Al4V 
EXPERIMENTAL RESULTS 
Residual Stresses (According to ASTM E837-08) 
Al2024-T351 
Smax in Al2024-T351 for different 
irradiation intensities 
Smax in Ti6Al4V for different irradiation 
intensities 
EXPERIMENTAL RESULTS 
Ti6Al4V 
Residual Stresses (According to ASTM E837-08) 
Al2024-T351 
Smax and Smio  extremes reached in Al2024-T351 
for different irradiation intensities 
Compressively protected depth (100 MPa) reached 
in Al2024-T351 for different irradiation intensities 
EXPERIMENTAL RESULTS 
Residual Stresses (According to ASTM E837-08) 
Ti6Al4V 
Smax and Smio  extremes reached in Ti6Al4V 
for different irradiation intensities 
Compressively protected depth (100-200 MPa) 
reached in Ti6Al4V for different irradiation intensities 
EXPERIMENTAL RESULTS 
Residual Stresses (According to ASTM E837-08) 
Ti6Al4V: Comparison LSP-Shot Peening 
Substantial improvement in Residual Stresses 
Field in Ti6Al4V vs. to Shot Peening 
Decisive improvement in protected depth reached in 
Ti6Al4V for different irradiation intensities 
EXPERIMENTAL RESULTS 
Residual Stresses Permanence upon Thermal Treatment 
AISI 316L Steel 
Smax permanence in AISI 316L Steel after 
different Thermal Treatment Temperatures for a 
900 pulses/cm2 LSP Treatment Intensity 
0,0 0,2 0,4 0,6 0,8 1,0
-700
-600
-500
-400
-300
-200
-100
0
100
Steel AISI 316L, 900 pulses/cm2, l = 1064 nm
2.8 J/pulse, spot diameter = 1,5 mm, water jet, no paint
Re
si
du
al
 s
tre
ss
es
 (M
Pa
)
Depth (mm)
 
 
 Smax, 25ºC
 Smax, 400ºC - 8 h
 Smax, 500ºC - 8 h
 Smax, 600ºC - 8 h
Smax permanence in AISI 316L Steel after 
different Thermal Treatment Temperatures for a 
1600 pulses/cm2 LSP Treatment Intensity 
0,0 0,2 0,4 0,6 0,8 1,0
-700
-600
-500
-400
-300
-200
-100
0
100
Steel AISI 316L, 1600 pulses/cm2, l = 1064 nm
2.8 J/pulse, spot diameter = 1,5 mm, water jet, no paint
Re
si
du
al
 s
tre
ss
es
 (M
Pa
)
Depth (mm)
 
 
 Smax, 25ºC
 Smax, 400ºC - 8 h
 Smax, 500ºC - 8 h
 Smax, 600ºC - 8 h
EXPERIMENTAL RESULTS 
 
 
 
 
 
 
Experimental setup LSP CLUPM 900 pul/cm2 1600 pul/cm2 
900 
pulses/cm2 
1600 
pulses/cm2 
900 
pulses/cm2 + 
Heat treat.: 
500 ˚C, 8h 
Process parameters 
Wavelength (nm) 1064 
Frecuency (Hz) 10 
Energy (J/pulse) 2.8 
Pulse width (ns) ~ 9 
Spot diameter (mm) ~ 1.5 
Overlapping (pulses/cm2) 
900 
1600 
Confining medium Water jet 
Absorbent coating No 
EXPERIMENTAL RESULTS 
EXPERIMENTAL RESULTS 
0.0 0.2 0.4 0.6 0.8 1.0
-800
-700
-600
-500
-400
-300
-200
-100
0
100
AISI 316L Stainless steel, l = 1064 nm
2.8 J/pulse, Spot diameter = 1.5 mm, Water jet, whithout paint
Re
si
du
al
 s
tre
ss
es
 (M
Pa
)
Depth (mm)
 
 
 Smax, 900 pulses/cm2
 Smin, 900 pulses/cm2
 Smax, 1600 pulses/cm2
 Smin, 1600 pulses/cm2
Residual Stresses: 
0.0 0.2 0.4 0.6 0.8 1.0
-800
-700
-600
-500
-400
-300
-200
-100
0
100
AISI 316L Stainless steel, 900 pulses/cm2, l = 1064 nm
2.8 J/pulse, Spot diameter= 1.5 mm, Water jet, without paint
Re
si
du
al
 s
tre
ss
es
 (M
Pa
)
Depth (mm)
 
 
 Smin, 25ºC
 Smin, 500ºC - 8 h
 Smax, 25ºC
 Smax, 500ºC - 8 h
 
 
 
 
 
 
“Bone” Fatigue Specimen  
 ASTM E 466 
“Sub-size” Tensile Specimen 
 ASTM E 8M 
EXPERIMENTAL RESULTS 
EXPERIMENTAL RESULTS 
Tensile Tests: 
0 10 20 30 40 50
0
100
200
300
400
500
600
700
St
re
ss
 (M
Pa
)
Strain (%)
 Base material
 LSP 900
 LSP 1600
Property Base material LSP 900 LSP 1600 
Young Modulus (GPa) 177.205 182.099 185.446 
Engineering elastic limit (MPa) 355.410 356.390 359.930 
Maximun tensile stress (MPa) 633.608 629.700 626.870 
EXPERIMENTAL RESULTS 
Fatigue Tests: 
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
100000 1000000
 
 
 Base material
Cycles to failure
S a
 (M
Pa
)
LogN=16.33764-4.79302LogSa
R2=0.99760
Base Material:  AISI 316L Stainless Steel
Sa (Mpa) SMax (Mpa) Fmax (kN) Fmean (kN) Cycles
280 622 54.507 29.979 37752
270 600 52.560 28.908 49580
260 578 50.613 27.837 51513
250 556 48.667 26.767 71850
240 533 46.720 25.696 92466
230 511 44.773 24.625 105771
220 489 42.827 23.555 131677
210 467 40.880 22.484 157696
200 444 38.933 21.413 184158
190 422 36.987 20.343 260974
180 400 35.040 19.272 264889
170 378 33.093 18.201 661126
160 356 31.147 17.131 1000000
EXPERIMENTAL RESULTS 
Fatigue Tests: 
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
100000 1000000
 
 
 Base material
 LSP 900
 LSP 1600
Cycles to failure
S a
 (M
Pa
)
LogN=16.33764-4.79302LogSa
R2=0.99760
LogN=22.51020-7.35620LogSa
R2=0.98967
LogN=21.09071-0.01178Sa
R2=0.87937
AISI 316L Stainless Steel + LSP 900 + LSP 1600 pulses/cm2
Sa (Mpa) Smax (Mpa) Fmax (kN) Fmean (kN) Cycles 900 Cycles 1600
280 622 54.507 29.979 35574 60199
260 578 50.613 27.837 57777 75105
240 533 46.720 25.696 91471 107098
230 511 44.773 24.625 130302 165560
220 489 42.827 23.555 233301 185802
210 467 40.880 22.484 268180 444006
200 444 38.933 21.413 1000000 1000000
EXPERIMENTAL RESULTS 
Fatigue Tests: 
150
160
170
180
190
200
210
220
230
240
250
260
270
280
290
300
100000 1000000
 
 
 Base Material
 LSP 900
 LSP 900 Heat Treatment
Cycles to failure
S a
 (M
Pa
)
LogN=16.33764-4.79302LogSa
R2=0.99760
LogN=22.51020-7.35620LogSa
R2=0.98967
LogN=17.00022-5.03482LogSa
R2=0.99
LSP 900 + Heat treatment (500ºC; 8h) 
Sa (Mpa) SMax (Mpa) Fmax (kN) Fmean (kN) Cycles
280 622 54.507 29.979 6000
230 511 44.773 24.625 128632
200 444 38.933 21.413 259987
180 400 35.040 19.272 1000000
10 100
0,00
0,02
0,04
0,06
0,08
0,10
Aluminium 6061-T6, 1064 nm
Spot diameter = 1.5 mm
2500 pulses/cm2
1350 pulses/cm2
900 pulses/cm2
No LSP
 
 
 2500 pulses/cm2
 1350 pulses/cm2
 900 pulses/cm2
 No LSP
da
/d
N 
(m
m
/c
yc
le
)
K (MPa . m1/2)
Rubio-González, C. et al.: Mat. Sci. Eng. A., 386 (2004) 291-295 
EXPERIMENTAL RESULTS 
28 
DISCUSSION AND OUTLOOK 
Problem 
Solution 
A typical prospective LSP application to welding technology 
29 
DISCUSSION AND OUTLOOK 
International Journal of Fatigue 31 (2009) 974–988 
30 
DISCUSSION AND OUTLOOK 
8
Tensile tests
The tension test was made at a constant 
crosshead speed of v = 1 mm/min
Instron 1275 servo-hydraulic universal testing machine 
2 extensometers Instron 2620-602 with different
gauge lengths (12.5 and 25 mm) were used to
capture the overall strains developed in tension
into the FSW joint with/without LSP treatment
4. Mechanical characterization
9
Engineering stress-strain curves of: 1- FSW joint; 2- FSW joint with LSP surface treatment; 
3- native base metal AA2024-T351; 4- AA2024-T351 with LSP surface treatment
4. Mechanical characterization
31 
DISCUSSION AND OUTLOOK 
10
4. Mechanical characterization
Digital Image Correlation System – VIC 2D
Light SourceCamera
Sample2D analysis
speckle patterns on the sample surface
Image 0 Deformed Image 
VIC software correlates location of random speckle patterns
between two images.
The correlation is made between windows of
pixels, typically 25 x 25 pixels, so measured
values are averages over the window size
In-plane strain 
measurement 
12
4. Mechanical characterization
FSW joint - Local Strain analysis
1- overall ; 2 – AS; 3 - RS; 4 – WZ; 5 – BM
1
2 3
4
5
Virtual longitudinal extensometers position
32 
DISCUSSION AND OUTLOOK 
19
4. Mechanical characterization
FSW  vs. FSW-LSP treated joint - Local Strain analysis
RS vs. WZ strains (FSW joint with/without LSP)
AS vs. WZ strains (FSW joint with/without LSP)
21
4. Mechanical characterization
FSW  vs. FSW-LSP treated joint - Local Strain analysis
FSW joint vs. BM strains (with/without LSP)
FSW joint vs. WZ strains (with/without LSP)
33 
§ With the aid of the experimental irradiation and process diagnosis system implemented at 
CLUPM (Spain), a complete feasibility of the LSP technique at laboratory scale for the 
induction of improved material surface properties has been accomplished. The 
implementation of the appropriate experimental diagnosis methods enables a reliable process 
predictive assessment capability in view of process industrial implementation. 
 
§ On the other side, the need for a practical capability of LSP process control in practical 
applications has led to the joint development of comprehensive theoretical/computational 
models and related material properties characterization capabilities able to properly assess 
the complex material issues arising in the process. 
 
§ With the aid of the developed experimental testing capability, a specifically targeted analysis 
of LSP induced effects (such as surface morphology, surface composition transformations, 
surface mechanical behaviour, deep residual stress fields and others) is made possible, thus 
allowing a practical development of the technique from an industrial point of view. 
 
§ Representative applications of the LSP technique to the treatment of typical aeronautic grade 
alloys (typically Al and Ti) and stainless steels characteristic of the aerospace, nuclear, 
biomedical and equipment industries, as well as to the post-treatment of welded metallic joints 
have been successfully conducted to the induction of compressive residual stresses fields 
decisively improving their fatigue life. 
DISCUSSION AND OUTLOOK 
34 
DISCUSSION AND OUTLOOK 
LASER PLASMA INTERACTION 
SIMULATION AND DIAGNOSIS 
NUMERICAL SIMULATION 
OF SOLID BEHAVIOUR 
 
 
EXPERIMENTAL CHARACTERIZATION 
 OF MATERIAL PROPERTIES 
35 
1. Ocaña, J.L. et al.: “A Model for the Coupled Predictive Assessment of Plasma Expansion and Material 
Compression in Laser Shock Processing Applications”. In: High-Power Laser Ablation II, Claude R. 
Phipps, Masayuki Niino, Eds., SPIE Proceedings , Vol. 3885, 252–263 (2000) 
2. Ocaña, J.L. et al.: “Predictive assessment and experimental characterization of the influence of 
irradiation parameters on surface deformation and residual stresses in laser shock processed metallic 
alloys”. In: High-Power Laser Ablation V, Phipps C.R., Ed.. SPIE Vol. 5548, 642-653 (2004) 
3. Ocaña, J.L. et al.: Appl. Surf. Sci., 238 (2004) 242-248 
4. Ocaña, J.L. et al.: Appl. Surf. Sci., 238 (2004) 501-505  
5. Rubio-González, C. et al.: Mat. Sci. Eng. A., 386 (2004) 291-295 
6. Ocaña, J.L. et al.: “Laser Shock Processing as a Method for Surface Properties Modification of Metallic 
Materials”. In: Shot Peening and other Mechanical Surface Treatments, V. Shulze, A. Niku-Lari, Eds. 
I.I.T.T. Paris (2005), 466-471. 
7. Sanchez-Santana, U., et al.:  Wear, 260 (2006) 847-854 
8. Rubio-González, C. et al.: Appl. Surf. Sci., 252 (2006) 6201-6205 
9. Morales, M. et al.: “Numerical Simulation of Plasma Dynamics in Laser Shock Processing Experiments”. 
In: Proceedings of LPM2008. 1-6 (2008) 
10. Morales, M. et al.: Surf. & Coat. Tech. 202 (2008) 2257–2262 
11. Martí-López, L. et al.: Appl. Opt. 48 (2009) 3671-3680 
12. Morales, M. et al.: Appl. Surf. Sci. 255 (2009) 5181–5185 
13. Ocaña, J.L. et al.: Mat. Sci. Forum, Vols. 638-642 (2010) pp 2446-2451 
14. Morales, M. et al.: Mat. Sci. Forum, Vols. 638-642 (2010) pp 2682-2687 
15. Morales, M. et al.:  J. Optoelectr. and Adv. Mat., 12 (2010) 718-722 
ACKNOWLEDGEMENTS 
REFERENCES 
Work supported by MEC/MCINN (Spain; Projects DPI2005-09152-C02-01; MAT2008-02704/MAT) and EADS-
CASA (Spain)  
36 
DISCUSSION AND OUTLOOK 
LSP: An emerging industrial technology 
LSP: An Emerging Sustainability Supporting Technology 
Next event on LSP: 
Contact:  jlocana@etsii.upm.es 
http://www.upmlaser.upm.es/4-ICLPRP   
38 
Thank you very much 
for your attention ! 
 
 
jlocana@etsii.upm.es 
 
39 
NUMERICAL SIMULATION. MODEL DESCRIPTION 
The SHOCKLAS Calculational System 


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Application of high-intensity short-pulse lasers to the mechanical and surface properties improvement of high reliability metallic components by shock processing

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