scholarly journals A Mechanism for Inducing Compressive Residual Stresses on a Surface by Laser Peening without Coating

Metals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 816 ◽  
Author(s):  
Yuji Sano ◽  
Koichi Akita ◽  
Tomokazu Sano
Keyword(s):  
Single Pulse ◽  
Laser Pulses ◽  
Mechanical Effect ◽  
Intense Laser ◽  
Laser Peening ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intense Laser Pulses ◽  
Laser Peening Without Coating ◽  
Compressive Residual Stresses

Laser peening without coating (LPwC) involves irradiating materials covered with water with intense laser pulses to induce compressive residual stress (RS) on a surface. This results in favorable effects, such as fatigue enhancement; however, the mechanism underlying formation of the compressive RS is not fully understood. In general, tensile RS is imparted on the surface of the material due to shrinkage after heating by laser irradiation. In this study, we assessed the thermo-mechanical effect of single laser pulse irradiation and introduce a phenomenological model to predict the outcome of LPwC. To validate this model, RS distribution across the laser-irradiated spot was analyzed using X-ray diffraction with synchrotron radiation. In addition, the RS was evaluated across a line and over an area, following irradiation by multiple laser pulses with partial overlapping. Large tensile RSs were found in the spot irradiated by the single pulse; however, compressive RSs appeared around the spot. In addition, the surface RS state shifted to the compressive side due to an increase in overlap between neighboring laser pulses on the line and over the area of irradiation. The compressive RSs around a subsequent laser spot effectively compensated the tensile component on the previous spot by controlling the overlap, which may result in compressive RSs on the surface after LPwC.

scholarly journals K-shell x-ray emission enhancement via self-guided propagation of intense laser pulses in Ar clusters

2009 ◽  
Vol 17 (19) ◽  
pp. 16379 ◽  
Author(s):  
Feng Liu ◽  
Li-Ming Chen ◽  
Xiao-Xuan Lin ◽  
Feng Liu ◽  
Jing-Long Ma ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Intense Laser ◽  
X Ray ◽  
Intense Laser Pulses ◽  
Emission Enhancement ◽  
Guided Propagation

scholarly journals Quarter Century Development of Laser Peening without Coating

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 152 ◽  
Author(s):  
Yuji Sano
Keyword(s):  
Pulse Energy ◽  
Nuclear Power ◽  
Surface Preparation ◽  
Laser Pulses ◽  
Intense Laser ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Quarter Century ◽  
Pulse Density ◽  
Laser Peening Without Coating

This article summarizes the development of laser peening without coating (LPwC) during the recent quarter century. In the mid-1990s, the study of LPwC was initiated in Japan. The objective at that time was to mitigate stress corrosion cracking (SCC) of structural components in operating nuclear power reactors (NPRs) by inducing compressive residual stresses (RSs) on the surface of susceptible components. Since the components in NPRs are radioactive and cooled underwater, full-remote operation must be attained by using lasers of water-penetrable wavelength without any surface preparation. Compressive RS was obtained on the top-surface by reducing pulse energy less than 300 mJ and pulse duration less than 10 ns, and increasing pulse density (number of pulses irradiated on unit area). Since 1999, LPwC has been applied in NPRs as preventive maintenance against SCC using frequency-doubled Q-switched Nd:YAG lasers (λ = 532 nm). To extend the applicability, fiber-delivery of intense laser pulses was developed in parallel and has been used in NPRs since 2002. Early first decade of the 2000s, the effect extending fatigue life was demonstrated even if LPwC increased surface roughness of the components. Several years ago, it was confirmed that 10 to 20 mJ pulse energy is enough to enhance fatigue properties of weld joints of a structural steel. Considering such advances, the development of 20 mJ-class palmtop-sized handheld lasers was initiated in 2014 in a five-year national program, ImPACT under the cabinet office of the Japanese government. Such efforts would pave further applications of LPwC, for example maintenance of infrastructure in the field, beyond the horizons of the present laser systems.

scholarly journals Role of the laser wavelength in the X-ray production for clusters under intense laser pulses

2014 ◽  
Vol 488 (13) ◽  
pp. 132021
Author(s):  
C Prigent ◽  
M Comte ◽  
O Gobert ◽  
D Guillaumet ◽  
J Habib ◽  
...  
Keyword(s):  
Laser Pulses ◽  
Laser Wavelength ◽  
Intense Laser ◽  
X Ray ◽  
Intense Laser Pulses

scholarly journals Effects of Laser Peening with a Pulse Energy of 1.7 mJ on the Residual Stress and Fatigue Properties of A7075 Aluminum Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1716
Author(s):  
Yuji Sano ◽  
Kiyotaka Masaki ◽  
Yoshio Mizuta ◽  
Satoshi Tamaki ◽  
Tomonao Hosokai ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Pulse Energy ◽  
Laser Pulses ◽  
Microchip Laser ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Robot Arm ◽  
X Ray Diffraction ◽  
Bending Fatigue ◽  
Laser Peening Without Coating

Laser peening without coating (LPwC) using a palmtop-sized microchip laser has improved the residual stresses (RSs) and fatigue properties of A7075 aluminum alloy. Laser pulses with a wavelength of 1.06 μm and duration of 1.3 ns from a Q-switched Nd:YAG microchip laser were focused onto A7075 aluminum alloy samples covered with water. X-ray diffraction revealed compressive RSs on the surface after irradiation using laser pulses with an energy of 1.7 mJ, spot diameter of 0.3 mm, and density of 100–1600 pulse/mm2. The effects were evident to depths of a few hundred micrometers and the maximum compressive RS was close to the yield strength. Rotation-bending fatigue experiments revealed that LPwC with a pulse energy of 1.7 mJ significantly prolonged the fatigue life and increased the fatigue strength by about 100 MPa with 107 fatigue cycles. The microchip laser used in this study is small enough to fit in the hand or be mounted on a robot arm. The results may lead to the development of tools that extend the service life of various metal parts and structures, especially outdoors where conventional lasers are difficult to apply.

scholarly journals The High Energy Density Scientific Instrument at the European XFEL

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
Ulf Zastrau ◽  
Karen Appel ◽  
Carsten Baehtz ◽  
Oliver Baehr ◽  
Lewis Batchelor ◽  
...  
Keyword(s):  
Energy Density ◽  
Laser Pulses ◽  
High Energy ◽  
High Energy Density ◽  
Intense Laser ◽  
Scientific Instrument ◽  
X Ray ◽  
Intense Laser Pulses ◽  
Pulsed Magnets ◽  
Beam Parameters

The European XFEL delivers up to 27000 intense (>1012 photons) pulses per second, of ultrashort (≤50 fs) and transversely coherent X-ray radiation, at a maximum repetition rate of 4.5 MHz. Its unique X-ray beam parameters enable groundbreaking experiments in matter at extreme conditions at the High Energy Density (HED) scientific instrument. The performance of the HED instrument during its first two years of operation, its scientific remit, as well as ongoing installations towards full operation are presented. Scientific goals of HED include the investigation of extreme states of matter created by intense laser pulses, diamond anvil cells, or pulsed magnets, and ultrafast X-ray methods that allow their diagnosis using self-amplified spontaneous emission between 5 and 25 keV, coupled with X-ray monochromators and optional seeded beam operation. The HED instrument provides two target chambers, X-ray spectrometers for emission and scattering, X-ray detectors, and a timing tool to correct for residual timing jitter between laser and X-ray pulses.

scholarly journals Nonlinear Thomson backscattering of intense laser pulses by electrons trapped in plasma-vacuum boundary

2009 ◽  
Vol 27 (3) ◽  
pp. 365-370 ◽  
Author(s):  
Jiansheng Liu ◽  
Changquan Xia ◽  
Li Liu ◽  
Ruxin Li ◽  
Zhizhan Xu
Keyword(s):  
Laser Field ◽  
Second Harmonic ◽  
Laser Pulses ◽  
Intense Laser ◽  
Intense Laser Pulse ◽  
Spectral Filtering ◽  
Plasma Surface ◽  
X Ray ◽  
Intense Laser Pulses ◽  
Relativistic Factor

AbstractWe present the idea of intensified attosecond X-ray generation based on nonlinear Thomson backscattering of an intense laser pulse by electrons trapped in plasma-vacuum boundary. Two frequency up-conversions due to the relativistic Doppler effect and longitudinal γ-spike effect are analyzed, respectively, where γ is the relativistic factor of the plasma surface. Relativistic resonance heating conditions should be used as a criterion for the experimental design to obtain efficient high-order harmonics and energetic electrons' generation at relatively low laser intensities. Shaping the laser field by proposing a detuned second-harmonic can generate a single attosecond pulse without spectral filtering.

Sign in / Sign up

Export Citation Format

Share Document