scholarly journals The Effect of Hot-Mounting on the Microstructure of an As-Quenched Auto-Tempered Low-Carbon Martensitic Steel

Metals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 550 ◽  
Author(s):  
Shashank Ramesh Babu ◽  
Matias Jaskari ◽  
Antti Järvenpää ◽  
David Porter
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Scanning Electron Microscope ◽  
Martensitic Steel ◽  
Low Carbon ◽  
Martensitic Steels ◽  
Potential Growth ◽  
Scanning Electron ◽  
Additional Tempering ◽  
Carbon Martensitic Steel

The effect of hot-mounting for metallographic studies of as-quenched low-carbon martensitic steels has been studied. Hot-mounting is typically carried out at 150–200 °C, i.e., a low-temperature tempering regime. Cold- and hot-mounted specimens from an as-quenched low-carbon auto-tempered steel were examined using a scanning electron microscope and their hardness levels were also compared. It was found that hot-mounting causes additional tempering that manifests as the appearance of new precipitates in those regions that are free of auto-tempered cementite. The observations were rationalized using DICTRA simulations to calculate the potential growth of cementite. Hot-mounting was also shown to cause a small but statistically significant increase in the hardness of the martensite.

scholarly journals Image Processing Tool Quantifying Auto-Tempered Carbides in As-Quenched Low Carbon Martensitic Steels

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 171 ◽  
Author(s):  
Shashank Ramesh Babu ◽  
Thomas Paul Davis ◽  
Tim Haas ◽  
Antti Jarvenpää ◽  
Jukka Kömi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Image Processing ◽  
Image Segmentation ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Volume Fraction ◽  
Low Carbon ◽  
Martensitic Steels ◽  
Color Map ◽  
Scanning Electron

As-quenched low-carbon martensitic steels (<0.2 wt.% C) contain auto-tempered carbides. Auto-tempering improves the work hardening and upper-shelf impact energy; however, an efficient characterization method to determine the degree of auto-tempering has not been available. This paper demonstrates an efficient image processing tool that calculates the relative auto-tempered carbide fraction by analyzing scanning electron microscope micrographs. By the process of image segmentation, the qualitative volume fraction of auto-tempered carbides can be determined, and an associated color map produced, which distinguished the levels of auto-tempering. This image processing tool could become useful for the optimization of new low-carbon steel’s mechanical properties.

The Oxide Inclusion and Heat-Affected-Zone Toughness for Low Carbon Bridge Steels

2012 ◽  
Vol 562-564 ◽  
pp. 31-34
Author(s):  
Shu Rui Li ◽  
Xue Min Wang ◽  
Chao Chao Zheng ◽  
Xin Lai He
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Scanning Electron Microscope ◽  
Impact Energy ◽  
Heat Input ◽  
Oxide Inclusion ◽  
Optical Microscope ◽  
Low Carbon ◽  
Temperature Impact ◽  
Scanning Electron

By welding thermo-simulation and actual welding practices, the microstructure and properties of low carbon bridge steels has been studied with the aid of optical microscope, scanning electron microscope. The experimental results show that by the oxide introducing melting technology there are many complex inclusions composed of oxide containing Ti and MnS. These inclusions are spherical and they are distributed homogeneously. During the welding thermo-simulation these oxide inclusions will promote the nucleation of acicular ferrite and make the microstructure in HAZ finer. Therefore the toughness in HAZ is good whether in welding thermo-simulation even if the heat input reaches to 200kJ/cm. In actual welding the heat input is 88kJ/cm and the low temperature impact energy still can reach 110J.

scholarly journals Magnetism and Microstructure Characterization of Phase Transitions in a Steel

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
M. Güler
Keyword(s):  
Mössbauer Spectroscopy ◽  
Phase Transitions ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Mossbauer Spectroscopy ◽  
Low Carbon Steel ◽  
Magnetic Characteristics ◽  
Low Carbon ◽  
Mößbauer Spectroscopy ◽  
Scanning Electron

We present phase transitions in a low carbon steel according to existing phases and their magnetism. Scanning electron microscope employed research to clarify and evaluate the microstructural details. Additionally, we utilized from Mössbauer spectroscopy for magnetic characteristics of different existed phases. Scanning electron microscope examinations showed that the pure state of the steel was fully in the ferrite phase with equiaxed grains. Moreover, subsequent heat treatments on the studied steel also ensured the first austenite and then pearlite phase formation. Mössbauer spectroscopy of these phases appeared as a paramagnetic single-line absorption peak for the austenite phase and ferromagnetic six-line spectra for both ferrite and pearlite phases. From Mössbauer data, we determined that the internal magnetic fields of ferrite and pearlite phases were as 32.2 Tesla and 31.3 Tesla, respectively.

Low-temperature Scanning Electron Microscope constructed with high-excitation objective lens

1989 ◽  
Vol 47 ◽  
pp. 734-735
Author(s):  
H. Koike ◽  
T. Inoué
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Low Temperature ◽  
Scanning Electron Microscope ◽  
Freeze Substitution ◽  
Objective Lens ◽  
Rapid Freezing ◽  
High Excitation ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature microscope technology can be traced back to the last century including the time of light microscope, and its history is over a hundred years. In the field of electron microscopy, low temperature techniques such as the freeze-fracture replica, freeze-sectioning, freeze-substitution, etc. were tested up to early 1960s. According to the progress of the rapid-freezing method, the freeze-substitution and freeze-etching replica methods have provided great successful results.The low temperature scanning electron microscope (LTSEM) was also tested by Echlin et al. in 1970, and thereafter, a number of LTSEM constructions were attempted. These LTSEMs are generally classified into two groups: the type with fracturing and coating facilities directly attached to the SEM column, and the group having a separated preparation chamber and a transfer device. The LTSEM so far constructed were reviewed comprehensively in greater detail. Some such instruments were designed taking account of stringent requirements of low temperature techniques. These systems, however, seemed to be too comprehensive, involving complex procedures as compared withe their resolutions. In comparison with the conspicuous results obtained by other low temperature techniques, the LTSEM can be regarded as still in the stage prior to practical application from the viewpoint of the high resolution. In consideration of these circumstances, the present paper aims at providing a new LTSEM to realize simple operation retaining the advantage of the ultrastructural preservation by the rapid-freezing and the high resolution by introducing the high-excitation objective lens.

Low temperature scanning electron microscope measurements on a Nb/Ta junction

1997 ◽  
Vol 279 (1-2) ◽  
pp. 85-94 ◽  
Author(s):  
J.B. le Grand ◽  
M.P. Bruijn ◽  
C. Patel ◽  
P.A.J. de Korte ◽  
S. Lemke ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Low Temperature ◽  
Scanning Electron Microscope ◽  
Temperature Scanning ◽  
Scanning Electron
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