Development and microstructural analysis of TiC/TiC-Ni coatings on 347H stainless steel using CO2 laser scanning

2003 ◽  
Author(s):  
Virendra Bansal ◽  
Jorge A. Ramos ◽  
David L. Bourell ◽  
Madhav Rao Govindaraju
Keyword(s):  
Stainless Steel ◽  
Co2 Laser ◽  
Laser Scanning ◽  
Microstructural Analysis

scholarly journals Mechanical Properties and Hydrogen Embrittlement of Laser-Surface Melted AISI 430 Ferritic Stainless Steel

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 140 ◽  
Author(s):  
W. K. Chan ◽  
C. T. Kwok ◽  
K. H. Lo
Keyword(s):  
Stainless Steel ◽  
Hydrogen Embrittlement ◽  
Strain Rate ◽  
Ferritic Stainless Steel ◽  
Laser Scanning ◽  
Electron Backscatter Diffraction ◽  
Microstructural Analysis ◽  
Scanning Speed ◽  
Laser Surface ◽  
Aisi 430

In the present study, the feasibility of laser surface melting (LSM) of AISI 430 ferritic stainless steel to minimize hydrogen embrittlement (HE) was investigated. LSM of AISI 430 steel was successfully achieved by a 2.3-kW high power diode laser (HPDL) with scanning speeds of 60 mm/s and 80 mm/s (the samples are designated as V60 and V80, respectively) at a power of 2 kW. To investigate the HE effect on the AISI 430 steel without and with LSM, hydrogen was introduced into specimens by cathodic charging in 0.1 M NaOH solution under galvanostatic conditions at a current density of 30 mA/cm2 and 25 °C. Detail microstructural analysis was performed and the correlation of microstructure with HE was evaluated. By electron backscatter diffraction (EBSD) analysis, the austenite contents for the laser-surface melted specimens V60 and V80 are found to be 0.6 and 1.9 wt%, respectively. The amount of retained austenite in LSM specimens was reduced with lower laser scanning speed. The surface microhardness of the laser-surface melted AISI 430 steel (~280 HV0.2) is found to be increased by 56% as compared with that of the substrate (~180 HV0.2) because of the presence of martensite. The degree of embrittlement caused by hydrogen for the charged and non-charged AISI 430 steel was obtained using slow-strain-rate tensile (SSRT) test in air at a strain rate of 3 × 10−5 s−1. After hydrogen pre-charging, the ductility of as-received AISI 430 steel was reduced from 0.44 to 0.25 while the laser-surface melted AISI 430 steel showed similar tensile properties as the as-received one. After LSM, the value of HE susceptibility Iδ decreases from 43.2% to 38.9% and 38.2% for V60 and V80, respectively, due to the presence of martensite.

Microstructures and Hardness of CO2 Laser Welds in 409L Ferritic Stainless Steel

2010 ◽  
Vol 48 (04) ◽  
pp. 297-304 ◽  
Author(s):  
Jong Pan Kong ◽  
Tae Jun Park ◽  
Hye Sung Na ◽  
Jeong Kil Kim ◽  
Sang Ho Uhm ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Co2 Laser ◽  
Laser Welds

Development of Laser Cleaning for Metallic Equipment

2018 ◽  
Author(s):  
L. Carvalho ◽  
W. Pacquentin ◽  
M. Tabarant ◽  
J. Lambert ◽  
A. Semerok ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Laser Scanning ◽  
Surface Defects ◽  
Complex Geometry ◽  
Laser Cleaning ◽  
304L Stainless Steel ◽  
Primary Coolant ◽  
Aisi 304L ◽  
Weight Percentage ◽  
Aisi 304L Stainless Steel

Laser cleaning study was performed on prepared samples using a nanosecond pulsed ytterbium fiber laser. To prepare samples, AISI 304L stainless steel samples were oxidized and implemented with non-radioactive contaminants in a controlled manner. In order to validate the cleaning process for metallic equipment polluted in nuclear installations, two types of contamination with europium (Eu) and with cobalt (Co) were studied. Eu was used as a simulator-product resulting from uranium fission, while Co — as an activation-product of nickel, which is a composing element of a primary coolant system of a reactor. The oxide layers have suffered laser scanning which was followed by the furnace treatment to obtain thicknesses in the range of 100 nm to 1 μm depending on the oxidation parameters [1] with a mean weight percentage of 1% of Eu and 1 % of Co in the volume of the oxide layer. Glow Discharge Optical Emission (GD-OES) and Mass Spectrometry (GD-MS) analyses have been performed to assess the efficiency of the cleaning treatment and to follow the distribution of residual contamination with a detection limit of 0.1mg/kg of Eu and Co. Decontamination rates up to 95.5 % were obtained. One of the identified reasons for this limitation is that the radionuclides are trapped in surface defects like micro cracks [2, 3]. Therefore, cleaning treatments have been applied on surface defects with controlled geometry and a micrometric aperture obtained by laser engraving and juxtaposition of polished sheets of AISI 304L stainless steel. The goal of this study is surface decontamination without either welding or inducing penetration of contamination into the cracks. GD-MS analysis and Scanning Electron Microscopy (SEM) were performed to analyze the efficiency of the treatment and the diffusion of contaminants in this complex geometry.

scholarly journals An attemp to use a pulsed CO2 laser for decontamination of radioactive metal surfaces

2000 ◽  
Vol 65 (5-6) ◽  
pp. 445-450 ◽  
Author(s):  
Scepan Miljanic ◽  
Natasa Stjepanovic ◽  
Milan Trtica
Keyword(s):  
Stainless Steel ◽  
Co2 Laser ◽  
Metal Surfaces ◽  
High Efficiency ◽  
Germanium Detector ◽  
Surface Cleaning ◽  
Activity Levels ◽  
Air Atmosphere ◽  
Pulsed Co2 Laser ◽  
Pulse Energies

There is a growing interest in laser radioactive decontamination of metal surfaces. It offers advantages over conventional methods: improved safety, reduction of secondary waste, reduced waste volume, acceptable cost. The main mechanism of cleaning by lasers is ablation. Apulsed TEACO2 laser was used in this work for surface cleaning in order to show that ablation of metal surfaces is possible even at relatively low pulse energies, and to suggest that it could be competitive with other lasers because of much higher energy efficiencies. A brief theoretical analysis was made before the experiments. The laser beam was focused using a KBr-lens onto a surface contaminated with 137 Cs (b-, t1/2 = 30.17 y). Three different metals were used: stainless steel, copper and aluminium. The ablated material was pumped out in an air atmosphere and transferred to a filter. The presence of activity on the filter was shown by a germanium detector-multichannel analyzer. The activity levels were measured by a GM counter. The calculated decontamination factors and collection factors showed that ablation occurs with a relatively high efficiency of decontamination. This investigation suggests that decontamination using a CO2 laser should be seriously considered.

scholarly journals Study on the Hot Deformation Characterization of Borated Stainless Steel by Hot Isostatic Pressing

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7110
Author(s):  
Yanbin Pei ◽  
Xuanhui Qu ◽  
Qilu Ge ◽  
Tiejun Wang
Keyword(s):  
Stainless Steel ◽  
Hot Deformation ◽  
True Strain ◽  
Hot Isostatic Pressing ◽  
Microstructural Analysis ◽  
Critical Conditions ◽  
True Strain Rate ◽  
Isostatic Pressing ◽  
Different Temperatures ◽  
Borated Stainless Steel

Borated stainless steel (BSS) specimens have a boron content of 1.86 wt%, and are prepared by hot isostatic pressing (HIP) conducted at different temperatures, ranging from 1000 to 1100 °C and a constant true strain rate (0.01, 0.1, 1 and 10 s−1). These tests, with observations and microstructural analysis, have achieved the hot deformation characteristics and mechanisms of BSS. In this research, the activation energy (Q) and Zener–Hollomon parameter (Z) were contrasted against the flow curves: Q = 442.35 kJ/mol. The critical conditions associated with the initiation of dynamic recrystallization (DRX) for BSS were precisely calculated based on the function between the strain hardening rate with the flow stress: at different temperatures from 1000 to 1100 °C: the critical stresses were 146.69–254.77 MPa and the critical strains were 0.022–0.044. The facts show that the boron-containing phase of BSS prevented the onset of DRX, despite the saturated boron in the austenite initiated DRX. The microstructural analysis showed that hot deformation promoted the generation of borides, which differed from the initial microstructure of HIP. The inhomogeneous distribution of elements in the boron-containing phase was caused by hot compression.

scholarly journals ABNORMAL TEMPERATURE FLUCTUATION OF STAINLESS STEEL IRRADIATED BY CW CO2 LASER

1999 ◽  
Vol 48 (12) ◽  
pp. 2246
Author(s):  
WEI XUE-QIN ◽  
ZHENG QI-GUANG ◽  
GU JIAN-HUI ◽  
LI ZAI-GUANG
Keyword(s):  
Stainless Steel ◽  
Co2 Laser ◽  
Temperature Fluctuation ◽  
Cw Co2 Laser ◽  
Abnormal Temperature

scholarly journals OPTICAL PROPERTIES OF LASER-COLOURING MARKED STAINLESS STEEL

2021 ◽  
Vol 3 ◽  
pp. 242-244
Author(s):  
Pavels Narica ◽  
Svetlana Pan’kova ◽  
Vladimir Solovyev ◽  
Alexander Vanin ◽  
Mikhail Yanikov
Keyword(s):  
Stainless Steel ◽  
Optical Properties ◽  
Light Scattering ◽  
Dielectric Permittivity ◽  
Laser Scanning ◽  
Incidence Angle ◽  
Sample Surface ◽  
Laser Scanning Microscopy ◽  
Optical Measurements ◽  
Complex Dielectric Permittivity

Laser colour-marking method often displace conventional marking techniques. Complicated technology of laser-induced periodic surface structure creation on stainless steel samples allows changing their surface morphology and optical properties, which were studied in this work by atomic force microscopy (AFM), laser scanning microscopy, reflectance spectroscopy and ellipsometry. Reflectance spectra of the samples demonstrate reflectance maxima correlate with the visible colours of the samples and with the extrema in the non-monotonic spectral dependences of the derivative of real part of complex dielectric permittivity extracted from the ellipsometric data. Thus, the most intensive light scattering takes place when the real part of complex dielectric permittivity falls down quickly with changing wavelength. We did not observe any “azimuth anisotropy” in our optical measurements at constant incidence angle: the spectra were the same independently of the light incidence plane orientation (parallel or perpendicular to the previous laser light spot scanning direction). We suppose that this selective resonance-like light scattering is due to the sample surface inhomogeneity, which is the result of previous laser treatment. This assumption agrees with estimations based on laser microscope and AFM images as well as with predictions of Mie theory. Thus, the colours of the samples under study are due to the light scattering by randomly distributed surface species with different sizes. 

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