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Investigation into laser shock processing

  • B. S. Yilbas
  • A. F. M. Arif
  • S. Z. Shuja
  • M. A. Gondal
  • J. Shirokof
Processing

Abstract

Laser shock processing is a good candidate for surface industry due to its rapid processing, localized ablation, and precision of operation. In the current study, laser shock processing of steel was considered. The numerical solutions for temperature rise and recoil pressure development across the interface of the ablating front and solid are presented. The propagation of elastic-plastic waves in the solid due to recoil pressure loading at the surface is analyzed and numerical solution for the wave propagation was obtained. An experiment was conducted to ablate the steel surfaces for shock processing. Scanning electron microscopy was carried out to examine the ablated surfaces shock processing while transmission electron microscopy was conducted to obtain dislocation densities after the shock processing. It was found that surface hardness of the workpiece increased in the order of 1.8 times of the base material hardness, and the dislocation was the main source of the shock hardening in the region affected by laser shock processing.

Keywords

ablation laser processing shock 

Nomenclature

A

area

co

elastic wave speed, m/s

c1

plastic wave speed, m/s

Cp

specific heat, J/kg.K

E

elastic modulus, Pa

h

plastic factor

H

hardness, HV

Io

laser peak power intensity, W/m2

k

thermal conductivity, W/m.K

kB

Boltzmann’s constant, 1.38 × 10−23 J/K

Lev

latent heat of evaporation, J/kg

m

atomic mass, kg

P

dislocation density, 1/cm2

Pr

Recoil pressure, Pa

\(\dot q\)solid

energy dissipated in the solid phase, W/m2

rf

reflection coefficient

T(x,t)

temperature, K

Ts

surface temperature, K

Tev

evaporation temperature, K

t

time, s

tp

Twice of pulse length, 18 ns

u

velocity in x-direction, m/s

U

displacement, m

V

recession velocity of the surface, m/s

Vev

vapor front velocity, m/s

x

spatial coordinates corresponding to the x,y,z axes for phonon, m

α

thermal diffusivity, m2/s

β

laser pulse parameter, 1/s

δ

absorption coefficient, 1/m

ε

strain

κ

yield stress, Pa

κo

elastic yield limit, Pa

λ

mean free path of electrons, m

ρ

density, kg/m2

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Copyright information

© ASM International 2004

Authors and Affiliations

  • B. S. Yilbas
    • 1
  • A. F. M. Arif
    • 1
  • S. Z. Shuja
    • 1
  • M. A. Gondal
    • 2
  • J. Shirokof
    • 3
  1. 1.ME DepartmentKFUPMDhahranSaudi Arabia
  2. 2.Laser Research Section, Center For Applied Physical SciencesKFUPMDhahranSaudi Arabia
  3. 3.Faculty of Engineering and Applied ScienceMemorial University of NewfoundlandCanada

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