Showing 5 results for Low Carbon Steel
Dehghan Manshadi A., Zarei Hanzaki A., Golmahalleh O.,
Volume 2, Issue 2 (6-2005)
Abstract
The presence of bainite in the microstructure of steels to obtain a proper combination of strength and toughness has always been desired. The previous works however have shown that the presence of preferred bainite morphologies in the microstructure of any steel would not be readily accessible. In addition, the appearance of different bainite morphologies in the microstructure of any steel is dictated by different factors including the steel initial microstructure, austenitization characteristics, thermomechanical processing parameters and so on. Accordingly, in the present work, the effect of prior austenite grain size and the amount of austenite hot deformation on the bainite formation characteristics were investigated in 0.12C-2.5 Ni-1.2Cr steels. The results indicated that the prior austenite grain size and the amount of deformation in the austenite no-recrystallization region resulted in significant changes of the bainite formation kinetics and morphology.
M. Shaban Ghazani, A. Vajd, B. Mosadeg,
Volume 12, Issue 1 (3-2015)
Abstract
The aim of the present study is the prediction of critical conditions (including critical strain and flow stress)
for the initiation of dynamic recrystallization during thermo-mechanical processing of plain carbon steels. For this
propose, torsion tests were conducted at different temperature (1050, 1100 and 1150˚C) and strain rates (0.002, 0.02
and 0.2/s). All flow curves showed a peak stress indicating that dynamic recrystallization occurs during hot
deformation. The critical stress and strain were then determined based on change in strain hardening rate as a function
of flow stress. Finally, the effect of deformation conditions on these parameters was analyzed.
A. Mohsenifar, M. R. Aboutalebi, S. H. Aboutalebi,
Volume 12, Issue 3 (9-2015)
Abstract
Hot dip aluminizing was carried out on the low carbon steel rod under optimized conditions. The aluminized
samples were further oxidized at 1000̊C in air atmosphere at two different times of 20 and 60 minutes. Microstructure
study and phase analysis were studied by scanning electron microscopy and X-ray diffraction methods, respectively.
The characterization of the coating showed that, Fe2
Al5
has been the major phase formed on the surface of specimen
before heat treatment. Following the oxidation of the coating at high temperature, Al
2O3
was formed on the surface of
coating while Fe
2
Al5
transformed into FeAl and Fe
3
Al which are favorable to the hot corrosion resistance of the
coating. Corrosion resistance of aluminized samples before and after heat treatment was evaluated by rotating the
samples in the molten aluminum at 700 ̊C for various times and the dissolution rate was determined. The obtained
results showed that by oxidizing the coating at high temperature, the corrosion resistance of the samples in molten
aluminum improves significantly.
Jonas Fernando Macedo, Igor Alexandre Fioravante, Roberto Zenhei Nakazato, Heloisa Andréa Acciari, Eduardo Norberto Codaro,
Volume 18, Issue 1 (3-2021)
Abstract
As we all know, corrosion of pipelines by hydrogen sulfide is the most worrying factor in the production and transport of oil and gas. In this work the corrosion behavior of API 5L X70MS and X70MO low carbon steels in hydrogen sulfide environments was investigated. Hydrogen induced cracking and sulfide stress cracking tests were carried out according to NACE TM0177 standard. After testing, blisters and cracks were observed only in X70MO steel, probably due to its lower grain refinement and banded microstructure. Internal cracks seem to be initiated in elongated MnS inclusions. Corrosion process was studied by obtaining potentiodynamic polarization curves, which were registered after open circuit potential measurements, at room temperature. Both steels showed general corrosion in NACE 177A solutions, but the corrosion rate values in H2S-saturated solution were about an order of magnitude higher than those ones in deaerated solution. Hydrogen permeation w::as char::acterized in accordance with ASTM G148 standard. In deaerated H2SO4 solution, permeation measurements were similar for both steels. In H2S-saturated solution, X70 MO exhibited higher hydrogen oxidation current values than X70 MS. H2S seems to promote the reduction of protons and increase the concentration of hydrogen atoms in the solution/steel interface, favoring the diffusion process. As X70MO has a coarse microstructure, it offers more pathways for hydrogen diffusion.
Seyed Mohammad Mirghasemi, Ehsan Mohammad Sahrifi, Gholam Hossein Borhani, Mirtaher Seyed Beigi,
Volume 21, Issue 4 (12-2024)
Abstract
In this study, the hot deformation and dynamic recrystallization behavior of low carbon steel containing 21 ppm boron was investigated. After homogenizing the samples at 1250 ℃ for 1-hour, hot compression tests were conducted at temperatures ranging from 850 ℃ to 1150 ℃ and strain rates from 0.01 to 10 s⁻¹, resulting in strain-stress flow curves. Following corrections, calculations and modeling were performed based on Arrhenius equations. Among them, the hyperbolic sine relationship provided the most accurate estimate and was selected as the valid model for the applied strain range. According to this model, the deformation activation energy (Q), was determined to be 293.37 KJ/mol. Additionally, critical and peak stress and strain values were obtained for each temperature and strain rate, and power relationships were established to describe their variation with respect to the Zener-Hollomon parameter (Z). Recrystallization fractions were derived by comparing the hypothetical recovery curves with the material flow curves, and the results were successfully modeled using the Kolmogorov-Johnson-Mehl-Avrami (KJMA) equation. The Avrami exponent was measured at approximately 2, indicating that nucleation predominantly occurred at grain boundaries. Microstructural analysis revealed that at higher Z values, recrystallization occurred along with a fraction of elongated grains, while lower Z values resulted in a greater fraction of equiaxed dynamic recrystallization (DRX) grains. The average grain sizes after compression tests at 950 ℃, 1050 ℃, and 1150 ℃ were measured as 21.9 µm, 30.4 µm, and 33.6 µm respectively at a strain rate of 0.1 s⁻¹, and 17.7 µm, 28.7 µm, and 31.3 µm at 1 s⁻¹. The overall microstructure displayed a more uniform grain size distribution with increasing deformation temperature.
