Effects of Nd: YAG Laser Welding Parameters on the Microstructure of 21% Cr Ferritic Stainless Steel

2011 ◽  
Vol 291-294 ◽  
pp. 999-1002
Author(s):  
Ke Ping Geng ◽  
Sheng Sun Hu ◽  
Jun Qi Shen ◽  
Jian Han ◽  
Hai Gang Xu
Keyword(s):  
Laser Welding ◽  
Optical Microscope ◽  
Welding Parameters ◽  
Slow Cooling ◽  
Yag Laser ◽  
Average Grain Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
The Relationship ◽  
Scanning Electron

21% Cr with Ti-Nb dual stabilized ferritic stainless was welded using Nd: YAG laser. The relationship between microstructure and parameters of laser welding was examined. The microstructure was investigated by using the optical microscope and scanning electron microscopes. The average grain size of the HAZ was increased with increasing heat input due to the slow cooling rate. Large precipitates as TiN, TiC and Nb(C,N) were dissolved in the HAZ. Fine precipitates which supposed to be TiC was formed uniformly distributed in the case of the fusion zones.

scholarly journals Dissimilar Metals Laser Welding between DP1000 Steel and Aluminum Alloy 1050

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 102 ◽  
Author(s):  
António Pereira ◽  
Ana Cabrinha ◽  
Fábio Rocha ◽  
Pedro Marques ◽  
Fábio Fernandes ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Laser Welding ◽  
Mechanical Tests ◽  
Welding Parameters ◽  
Dissimilar Metals ◽  
Butt Welding ◽  
Electron Microscopes ◽  
1050 Aluminum Alloy ◽  
Scanning Electron Microscopes

The welding of dissimilar metals was carried out using a pulsed Nd: YAG laser to join DP1000 steel and an aluminum alloy 1050 H111. Two sheets of each metal, with 30 × 14 × 1 mm3, were lap welded, since butt welding proved to be nearly impossible due to the huge thermal conductivity differences and melting temperature differences of these materials. The aim of this research was to find the optimal laser welding parameters based on the mechanical and microstructure investigations. Thus, the welded samples were then subjected to tensile testing to evaluate the quality of the joining operation. The best set of welding parameters was replicated, and the welding joint obtained using these proper parameters was carefully analyzed using optical and scanning electron microscopes. Despite the predicted difficulties of welding two distinct metals, good quality welded joints were achieved. Additionally, some samples performed satisfactorily well in the mechanical tests, reaching tensile strengths close to the original 1050 aluminum alloy.

Spectroscopic Analysis of the Plasma in Laser Welding of AZ31 Magnesium Alloy

2013 ◽  
Vol 341-342 ◽  
pp. 296-300
Author(s):  
Xiao Yan Gu ◽  
Huan Li ◽  
Ying Gao
Keyword(s):  
Magnesium Alloy ◽  
Laser Welding ◽  
Laser Plasma ◽  
Spectroscopic Analysis ◽  
Plasma Temperature ◽  
Cooling Effect ◽  
Az31 Magnesium Alloy ◽  
Welding Parameters ◽  
Yag Laser ◽  
The Relationship

AZ31 magnesium alloy was welded by the YAG laser. The plasma of laser welding was studied by the spectra and the plasma temperature was also calculated. The relationship between the welding parameters and plasma temperature was studied. The paper shows that the cooling effect of the plasma using helium is significant. Laser plasma temperature decreases from the center to the periphery and the temperature in the center is higher than 9000K. The evaporation of Mg element concentrates in the center of the laser plasma.

A comparison of optical microscope- and scanning electron microscope-based cathodoluminescence (CL) imaging and spectroscopy applied to geosciences

2008 ◽  
Vol 72 (4) ◽  
pp. 909-924 ◽  
Author(s):  
J. Götze ◽  
U. Kempe
Keyword(s):  
Electron Beam ◽  
Optical Microscope ◽  
Spectroscopic Studies ◽  
Electron Gun ◽  
Signal Acquisition ◽  
Imaging And Spectroscopy ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Similar Kind ◽  
Scanning Electron

AbstractCathodoluminescence (CL) imaging and spectroscopy are outstanding methods in several fields of geosciences. Cathodoluminescence can be examined using a wide variety of electron-beam equipment. Of special interest to geologists are optical microscopes (OMs) equipped with an electron gun. scanning electron microscopes (SEMs) and electron microprobes. Despite the similar kind of excitation, the results obtained may show marked differences. These are related to the use of focused or defocused as well as a scanned or stationary electron beam and the kind of signal acquisition. Images obtained by OM-CL (hot or cold acceleration) and SEM-CL differ due to different spatial resolution, true colour, grey-scale, or monochromatic detection, contrast inversion, phosphorescence effects, etc.Instrumentation used for spectroscopic studies may differ in sequential or parallel signal acquisition, wavelength range, spectral resolution, and the kind of analytical spot limitation. This is particularly important when investigating transient CL, rare earth element (REE) emissions, or luminescence in the near UV and IR regions as well as samples with small grain sizes and contrasting CL behaviour of adjacent mineral phases.In the present study, the influence of analytical parameters is demonstrated for certain mineral examples including zircon, fluorite, apatite, feldspar, quartz, corundum, kaolinite, and dickite.

Collection efficiency and acceptance maps of electron detectors for understanding signal detection on modern scanning electron microscopy

Microscopy ◽  
2018 ◽  
Vol 67 (1) ◽  
pp. 18-29
Author(s):  
Toshihide Agemura ◽  
Takashi Sekiguchi
Keyword(s):  
Optical Axis ◽  
Collection Efficiency ◽  
Detection Mechanism ◽  
Electron Trajectories ◽  
Backscattered Electron ◽  
Electron Microscopes ◽  
Working Distance ◽  
Scanning Electron Microscopes ◽  
The Relationship ◽  
Scanning Electron

Abstract Collection efficiency and acceptance maps of typical detectors in modern scanning electron microscopes (SEMs) were investigated. Secondary and backscattered electron trajectories from a specimen to through-the-lens and under-the-lens detectors placed on an electron optical axis and an Everhart–Thornley detector mounted on a specimen chamber were simulated three-dimensionally. The acceptance maps were drawn as the relationship between the energy and angle of collected electrons under different working distances. The collection efficiency considering the detector sensitivity was also estimated for the various working distances. These data indicated that the acceptance maps and collection efficiency are keys to understand the detection mechanism and image contrast for each detector in the modern SEMs. Furthermore, the working distance is the dominant parameter because electron trajectories are drastically changed with the working distance.

scholarly journals Giving your SEM or FIB a Helping Hand

2008 ◽  
Vol 16 (1) ◽  
pp. 16-19
Author(s):  
Neil Rowlands ◽  
Gavin Frayne ◽  
Bo Svarrer Hansen
Keyword(s):  
Sample Preparation ◽  
Optical Microscope ◽  
Semiconductor Technology ◽  
Precise Positioning ◽  
Electrical Test ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Scanning electron microscopes have traditionally been used for observation and microanalysis of samples. Positioning and testing of samples has usually been performed out of the SEM chamber e.g. electrical test benches, sample preparation. However, due to miniaturization in semiconductor technology, optics, micro-mechanics, medicine, gene- and biotechnology, highly precise positioning techniques are becoming increasingly important. This may be performed using an optical microscope, or more commonly, within the SEM chamber itself.

Current State of Biological High-Resolution Scanning Electron Microscopy

1988 ◽  
Vol 46 ◽  
pp. 180-181 ◽  
Author(s):  
Klaus-Ruediger Peters
Keyword(s):  
High Performance ◽  
Low Voltage ◽  
Backscattered Electrons ◽  
Lens Position ◽  
Low Voltage Operation ◽  
Signal Collection ◽  
Probe Size ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

A new generation of high performance field emission scanning electron microscopes (FSEM) is now commercially available (JEOL 890, Hitachi S 900, ISI OS 130-F) characterized by an "in lens" position of the specimen where probe diameters are reduced and signal collection improved. Additionally, low voltage operation is extended to 1 kV. Compared to the first generation of FSEM (JE0L JSM 30, Hitachi S 800), which utilized a specimen position below the final lens, specimen size had to be reduced but useful magnification could be impressively increased in both low (1-4 kV) and high (5-40 kV) voltage operation, i.e. from 50,000 to 200,000 and 250,000 to 1,000,000 x respectively.At high accelerating voltage and magnification, contrasts on biological specimens are well characterized1 and are produced by the entering probe electrons in the outmost surface layer within -vl nm depth. Backscattered electrons produce only a background signal. Under these conditions (FIG. 1) image quality is similar to conventional TEM (FIG. 2) and only limited at magnifications >1,000,000 x by probe size (0.5 nm) or non-localization effects (%0.5 nm).

Observation of GaAs/AlAs Superlattice Structures in both Secondary and Backscattcred Electron Imaging Modes with an Ultrahigh Resolution Scanning Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 404-405
Author(s):  
K. Ogura ◽  
A. Ono ◽  
S. Franchi ◽  
P.G. Merli ◽  
A. Migliori
Keyword(s):  
Gaas Layer ◽  
Objective Lens ◽  
Superlattice Structure ◽  
Backscattered Electron ◽  
Instrumental Resolution ◽  
Electron Microscopes ◽  
Superlattice Structures ◽  
Electron Imaging ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

In the last few years the development of Scanning Electron Microscopes (SEM), equipped with a Field Emission Gun (FEG) and using in-lens specimen position, has allowed a significant improvement of the instrumental resolution . This is a result of the fine and bright probe provided by the FEG and by the reduced aberration coefficients of the strongly excited objective lens. The smaller specimen size required by in-lens instruments (about 1 cm, in comparison to 15 or 20 cm of a conventional SEM) doesn’t represent a serious limitation in the evaluation of semiconductor process techniques, where the demand of high resolution is continuosly increasing. In this field one of the more interesting applications, already described (1), is the observation of superlattice structures.In this note we report a comparison between secondary electron (SE) and backscattered electron (BSE) images of a GaAs / AlAs superlattice structure, whose cross section is reported in fig. 1. The structure consist of a 3 nm GaAs layer and 10 pairs of 7 nm GaAs / 15 nm AlAs layers grown on GaAs substrate. Fig. 2, 3 and 4 are SE images of this structure made with a JEOL JSM 890 SEM operating at an accelerating voltage of 3, 15 and 25 kV respectively. Fig. 5 is a 25 kV BSE image of the same specimen. It can be noticed that the 3nm layer is always visible and that the 3 kV SE image, in spite of the poorer resolution, shows the same contrast of the BSE image. In the SE mode, an increase of the accelerating voltage produces a contrast inversion. On the contrary, when observed with BSE, the layers of GaAs are always brighter than the AlAs ones , independently of the beam energy.

Discoasters of the Blue Clay (Middle Miocene) of Malta and Gozo

1978 ◽  
Vol 115 (1) ◽  
pp. 1-19 ◽  
Author(s):  
Minoo Hojjatzadeh
Keyword(s):  
Middle Miocene ◽  
The Family ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

SummaryTwenty-three species of the Family Discoasteraceae Vekshina, 1959 recovered from 18 samples of the Blue Clay at Fort Chambray, Gozo, and 31 samples from Fomm-Ir-Rih Bay, Malta, have been studied under light and scanning electron microscopes. Fourteen Middle Miocene species are reviewed, their stratigraphical ranges and importance as marker species discussed. Nine species are described as new. On the basis of the discoaster species present, a Middle Miocene age (NN.6 Discoaster exilis Zone – NN.7 Discoaster kugleri Zone) for the Blue Clay in Malta and Gozo is suggested.

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