Experimental Study on Testing Ni-Containing Stainless Steel Protective Coatings by Pulsed Laser Scratching

In the experiment, we use pulsed laser to conduct discrete scratching on Ni-containing stainless steel protective coatings to test residual stress situation after the matrix is scratched; then to analyze the the impact of the impact stress wave on coating - substrate bonding strength according to the test results, finally to infer the laser power density range within which it occurs coating failure. The study shows that: after laser discrete scratching, the residual stress of the center of the laser-loaded point on matrix surface gradually reduces when the pulsed laser power density increases. The matrix produces a corresponding residual compressive stress under the laser power density reaches a certain value. The actual failure threshold values are 12.006 GW/cm2, 11.829GW/cm2 and 12.193GW/cm2 measured by the three-dimensional topography instrument testing the discrete scratch point of three groups of samples and verified by using a microscope

Download Full-text

Investigation on Residual Stress Loss during Laser Peen Texturing of 316L Stainless Steel

Applied Sciences ◽

10.3390/app9173511 ◽

2019 ◽

Vol 9 (17) ◽

pp. 3511 ◽

Cited By ~ 2

Author(s):

Kangmei Li ◽

Yifei Wang ◽

Yu Cai ◽

Jun Hu

Keyword(s):

Residual Stress ◽

Compressive Stress ◽

Power Density ◽

Laser Power ◽

Surface Deformation ◽

Laser Power Density ◽

Residual Compressive Stress ◽

Laser Spot ◽

Residual Tensile Stress ◽

Spot Radius

Laser peen texturing (LPT) is a novelty way of surface texturing based on laser shock processing. One of the most important benefits of LPT is that it can not only fabricate surface textures but also induce residual compressive stress for the target material. However, the residual stress loss leads to partial loss of residual compressive stress and even causes residual tensile stress at the laser spot center. This phenomenon is not conducive to improving the mechanical properties of materials. In this study, a numerical simulation model of LPT was developed and validated by comparison of surface deformation with experiments. In order to investigate the phenomenon of residual stress loss quantitatively, an evaluation method of residual stress field was proposed. The effects of laser power density and laser spot radius on the residual stress, especially the residual stress loss, were systematically investigated. It is found that with the increase of laser power density or laser spot radius, the thickness of residual compressive layer in depth direction becomes larger. However, both the magnitude and the affecting zone size of residual stress loss will be increased, which implies a more severe residual stress loss phenomenon.

Download Full-text

Preparation and Microstructure Control of Protein Thin Films Deposited by Pulsed Laser Deposition and Via Colloid Chemical Routes

MRS Proceedings ◽

10.1557/proc-788-l3.22 ◽

2003 ◽

Vol 788 ◽

Cited By ~ 3

Author(s):

Sayuri Nakayama ◽

Ichiro Taketani ◽

Sanshiro Nagare ◽

Mamoru Senna

Keyword(s):

Thin Film ◽

Secondary Structure ◽

Pulsed Laser Deposition ◽

Power Density ◽

Laser Power ◽

Pulsed Laser ◽

Laser Power Density ◽

Laser Deposition ◽

Random Coil ◽

Β Sheet

ABSTRACTProtein thin film (mainly silk fibroin) was prepared by pulsed laser deposition (PLD) with 1064nm IR-beam and via colloid chemical routes. Thickness, surface roughness, and microstructures of the deposited film were examined by quartz crystal microbalance sensor, field emission scanning electron microscope (FE-SEM), and atomic force microscope (AFM). The laser power density was varied systematically for PLD to control the microstructures of the film and the secondary structure (β-sheet, α-helix, or random coil) of the protein. Secondary structure of the target and film was examined by FT-IR. Films prepared by PLD comprise by agglomerated particles with their primary particle size around 30nm. The size of the primary particles was uniform, especially for the film prepared at low laser power density. At low laser power density, proportion of β-sheet increased and that of random coil decreased. Proportion of random coil was also increased by the wet colloidal process. PLD with low power density is most suitable to preserve the secondary structure in the protein thin film.

Download Full-text

Pulsed Laser Deposition of Diamond-Like Carbon Thin Films: Ablation Dynamics and Growth

MRS Proceedings ◽

10.1557/proc-438-593 ◽

1996 ◽

Vol 438 ◽

Cited By ~ 4

Author(s):

Peidong Yang ◽

Z. John Zhang ◽

Jiangtao Hu ◽

Charles M. Lieber

Keyword(s):

Thin Films ◽

Kinetic Energy ◽

Pulsed Laser Deposition ◽

Power Density ◽

Laser Power ◽

Large Fraction ◽

Pulsed Laser ◽

Laser Power Density ◽

Laser Deposition ◽

Diamond Like Carbon

AbstractThin films of diamond-like carbon have been grown by pulsed laser deposition using a Nd:YAG laser at 532 nm. Time-of-flight mass spectroscopy was used to investigate the effects of laser power density and background gas pressure on the plume characteristics including the species in the plume and the kinetic energy distribution of each species. We found that with increasing laser power density (1) the relative amount of C+ ions increases, (2) the kinetic energy distributions of C+ get broader and can be deconvoluted into fast and slow components, and (3) the kinetic energy of the fast component of C+ ions increases from several to 40 eV. The resistivity and the local carbon bonding in films grown under these same conditions were also characterized. It was found that there is direct correlation between the characteristics of fast part of C+ ions in the plume and the diamond-like properties of the thin films. Under optimal growth conditions diamond-like carbon films with a large fraction of sp3 bonding can be prepared, although the maximum fraction appears to saturate at 70%. The implications of these results are discussed.

Download Full-text

Effects of laser power density on the microstructure and microhardness of Ni–Al alloyed layer by pulsed laser irradiation

Optics & Laser Technology ◽

10.1016/j.optlastec.2010.06.001 ◽

2011 ◽

Vol 43 (1) ◽

pp. 138-142 ◽

Cited By ~ 7

Author(s):

Y. Yang ◽

J.D. Hu

Keyword(s):

Laser Irradiation ◽

Power Density ◽

Laser Power ◽

Pulsed Laser ◽

Laser Power Density ◽

Alloyed Layer ◽

Pulsed Laser Irradiation

Download Full-text

Impact of laser power density on tribological properties of Pulsed Laser Deposited DLC films

AIP Advances ◽

10.1063/1.4856335 ◽

2013 ◽

Vol 3 (12) ◽

pp. 122113 ◽

Cited By ~ 8

Author(s):

S. Gayathri ◽

N. Kumar ◽

R. Krishnan ◽

S. AmirthaPandian ◽

T. R. Ravindran ◽

...

Keyword(s):

Power Density ◽

Tribological Properties ◽

Laser Power ◽

Pulsed Laser ◽

Laser Power Density

Download Full-text

Effect of laser power density and deposition temperature on electrical and optical properties of pulsed laser ablated diamond-like carbon films

Applied Surface Science ◽

10.1016/0169-4332(94)00376-9 ◽

1995 ◽

Vol 86 (1-4) ◽

pp. 180-184 ◽

Cited By ~ 14

Author(s):

J. Levoska ◽

S. Leppävuori

Keyword(s):

Optical Properties ◽

Power Density ◽

Laser Power ◽

Deposition Temperature ◽

Pulsed Laser ◽

Carbon Films ◽

Laser Power Density ◽

Diamond Like Carbon ◽

Electrical And Optical Properties

Download Full-text

Effect of Laser Power Density and Scanning Speed on Residual Stress in Laser-Peened Aluminum Alloy

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.54.672 ◽

2005 ◽

Vol 54 (7) ◽

pp. 672-678 ◽

Cited By ~ 3

Author(s):

Kazuya KUSAKA ◽

Takeshi TANAKA ◽

Takao HANABUSA

Keyword(s):

Residual Stress ◽

Aluminum Alloy ◽

Power Density ◽

Laser Power ◽

Scanning Speed ◽

Laser Power Density

Download Full-text

Mechanical Response and Failure Evolution of 304L Stainless Steel under the Combined Action of Mechanical Loading and Laser Heating

Metals ◽

10.3390/met8080620 ◽

2018 ◽

Vol 8 (8) ◽

pp. 620 ◽

Cited By ~ 1

Author(s):

Mohsan Jelani ◽

Zewen Li ◽

Zhonghua Shen ◽

Najam Hassan ◽

Maryam Sardar

Keyword(s):

Stainless Steel ◽

Power Density ◽

Mechanical Loading ◽

Laser Heating ◽

Laser Power ◽

Failure Time ◽

Laser Power Density ◽

Simultaneous Action ◽

304L Stainless Steel ◽

Stress Strain

Deformation and fracture properties of structural materials are greatly influenced by the factors like applied load, state of stress, and temperature. A precise prediction of the material properties of stainless steel at elevated temperature is necessary for determining the load-carrying capacity of structures under severe conditions. The present work reports the deformation and failure characteristics of 304L stainless steel subjected to combined laser heating and mechanical loading. The effect of main parameters on stress-strain, fracture characteristics, failure time, and temperature profile of specimens have been explored. Specimens were subjected to prescribed loading states, and then irradiated by a continuous wave fiber (1.08 µm) laser. The stress-strain curves indicated that the specimens experienced slight strain hardening in a specific temperature range prior to fracture. The specimen’s ultimate failure time is found to be reduced by increasing either laser power density or preload level. Fracture on a microscopic scale was predominantly ductile, comprising dimples as well as micro-void nucleation, growth, and coalescence. With the increase of laser power density, dimples rupture is the primary fracture mode, while with the increase of preload value, relatively more in-depth and severe deformation effects were observed. The description and characterization of 304L stainless steel failure under the simultaneous action of laser heating and tensile stress have been explored in detail.

Download Full-text

Numerical Simulation and Response Analysis of Residual Stress Induced by Micro-Scale Laser Shock Peening in TiN Film

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.452-453.741 ◽

2012 ◽

Vol 452-453 ◽

pp. 741-745

Author(s):

Hong Yan Ruan ◽

Xiao Jiang Xie ◽

Shu Huang ◽

Jian Zhong Zhou

Keyword(s):

Residual Stress ◽

Power Density ◽

Process Parameters ◽

Laser Power ◽

Compressive Residual Stress ◽

Laser Power Density ◽

Laser Shock ◽

Laser Process ◽

Tin Film ◽

Shock Peening

The ABAQUS software was used to analyze the residual stress of TiN film treated by the single point micro-scale laser shock peening (μLSP). In view of the multi-factor effect of μLSP, the response surface methodology (RSM) of Design-Expert software was utilized to analyze the influence of laser process parameters on the residual stress in TiN film, based on the Box-Behnken experimental design methods, as a result, optimal combination of the laser process parameters was obtained. The results showed that μLSP can transform the tensile residual stress in the TiN film into the compressive residual stress, the compressive residual stress was gradually increasing with the increased laser power density, when the laser power density was 8 GW/cm2, the maximum compressive residual stress of the film surface was up to -350.48 MPa. In addition, as the laser power density increased, the maximum compressive residual stress was moving away from the spot center. The optimal combination of the laser process parameters of μLSP was obtained by the RSM, the laser power density was 7.6 GW/cm2, laser spot diameter was 283 μm, and the number of shocking was 2 times. Simulation results of the average residual stress was -248.76 MPa, while the predicting result of regression model was -245.31 MPa, the error was just 1.38 %. The results showed that μLSP was feasible for improving the residual stress distribution of TiN film, and the RSM can effectively optimize the process parameters of μLSP.

Download Full-text