2024-03-29T11:42:40Z
https://journal.issiran.com/?_action=export&rf=summon&issue=3897
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
Identification of Retained Austenite, Ferrite, Bainite and Martensite in the Microstructure of TRIP Steel
A.
Mostafapour
A.
Ebrahimpour
T.
Saied
Transformation induced plasticity (TRIP) steels have a vast application in automotive industry because of theirhigh strength, high ductility and hence excellent energy absorption capacity. These characteristics of TRIPsteels are due to the existence of retained austenite in their microstructures in the ambient temperature, whichtransforms to the martensite phase during deformation. The microstructure of TRIP steel contains various phasesand in the past-published studies mainly the volume fraction of retained austenite was investigated and thereis not a quantitative comprehensive investigation about all phases in the microstructure of this steel. The maingoal in this study is a comprehensive qualitative and quantitative investigation in various phases of TRIP steelmicrostructure. Therefore, a TRIP steel with chemical composition of 0.2C+ 1.43Si+ 1.58Mn was produced andits complicated microstructure which contained ferrite, bainite, martensite and retained austenite was investigatedusing X-Ray Diffractometry (XRD), optical microscopy (OM), field emission scanning microscopy (FE-SEM)and Electron backscatter diffraction (EBSD). The OM and FE-SEM results were used only to qualitative studiesand identification of the morphologies of the phases but the EBSD results and functions were used to qualitativeand quantitative studies. The volume fractions of retained austenite, ferrite+bainite and martensite phases werecalculated and the amounts of 11%, 82% and 7% were obtained, respectively. The volume fraction of retainedaustenite was also measured with XRD and the amount of 14.3% was obtained.
TRIP steel
XRD, FE-SEM
EBSD
Retained austenite
2016
12
01
1
6
https://journal.issiran.com/article_23706_bdd6d21e6a5789c775d6d729a33f1a7e.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
The Influence of HH Type Steel Microstructure on the Distortion Behavior of Grate Bar Part in the Indurating Machine of Pelletizing Plant
M.
Alizadeh
Y.
Palizdar
Grate bar is an industrial part which is used in the indurating furnace of an iron ore pelletizing plant. Steel part ofthe grate bars are expected to have high resistance to atmospheric oxidation because of its contact with hot gases(up to 920 °C) during the normal operation of the process. In this study, different samples from several sections ofused grate bars with apparent defects were selected. The microstructure of the selected samples from the affectedareas was studied via optical and scanning electron microscopy with EDS analysis. The results showed that theinternal oxidation would occur through the oxygen diffusion into the chromium carbide nets and caused the changeof chromium carbide to chromium oxide. Furthermore, internal oxidation led to the separation of the grains fromthe steel matrix and resulted in the dusting phenomenon. In order to modify the steel microstructure, Ti elementwas added to the melt in different levels during the casting process and the results showed that the presence ofTi could modify the carbides structure and consequently improve the oxidation resistance of the steel. The gratebars with new composition were placed in the furnace and the monitoring of the consumption of the grate barin Mobarakeh Steel Company pelletizing plant. In a six -month period revealed that the grate bar consumptiondecreased about 30%.
Heat resistant steel
Chromium carbide precipitation
Grate bar
Microstructure
2016
12
01
7
12
https://journal.issiran.com/article_23707_4f0ebbc0f24f5011dbba6fbca9ef1064.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
Exponential-type Constitutive Equation in Order to Use in Modeling the Warm Deformation of a Eutectoid Steel
M.
Rakhshkhorshid
H.
Rastegari
The main contribution of the present work is to investigate the capability of exponential-type constitutive equationto model the warm deformation flow curves of a eutectoid steel in the temperature range of 620-770 °C andat the strain rates in the range of 0.01-10 s-1 conducted on a Gleeble-1500 thermomechanical simulator. Warmdeformation in this temperature range facilitates the occurrence of dynamic spheroidization of cementite lamellaeas a softening process as well as some instabilities and microstructural defects. The prediction capability of theexamined model was assessed using the average absolute relative error (AARE) criterion. The obtained AAREwith the value of 7.39% for warm deformation modeling of the tested steel showed the acceptable performance ofthe examined model.
Warm deformation
Flow stress
Exponential-type constitutive equation
Eutectoid steel
Dynamic spheroidization
2016
12
01
13
18
https://journal.issiran.com/article_23708_22377746297679b6cb19675bf4db0045.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
Tribological Properties of B4C-Ni Cermet Coating Produced by HVOF Process on the Surface of 4130 Steel
M.
Rafiei
M.
Shamanian
M.
Salehi
H.
Mostaan
In this research, B4C-Ni cermet coating was sprayed on the surface of 4130 steel from B4C and Ni feed-stockpowders using high velocity oxy-fuel (HVOF) method. In order to characterize the tribological behavior of thecoating, ball on disk wear tests were done at the ambient temperature and under the loads of 1, 3 and 5 N.Phase analysis of the coating after spraying was studied by X-ray diffractometery (XRD). Microstructure of thecoating and wear track was evaluated by scanning electron microscopy (SEM), field emission scanning electronmicroscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The microhardness test was done to measurethe hardness of the produced coating. It was found that a good coating with suitable interface and no significantpores and cracks in the microstructure of coatings was formed. The main wear mechanism of the coating wasdelamination with some oxide layers due to the frictional heat during wear test.
B4C-Ni coating
Microstructure
Wear test
Delamination
2016
12
01
19
25
https://journal.issiran.com/article_23709_9207508b6b77675e0975da0e87ce1b35.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
Strain-Induced Martensite Transformation Simulations during Cold Rolling of AISI 301 Austenitic Stainless Steel
M.
Imaninezhad
T.
Yan
A.
Najafizadeh
Austenite is a semi-stable phase in most stainless steels that deforms to martensite under Md30 and forms martensitetype ά and ε due to the deformation in the steels. Since the distribution of strain induced martensite plays animportant role in achieving desired properties, the main objective of the present work is to model martensitedistribution of ά during cold rolling using finite element method and Olsen-Cohen model. In this study, thestrain induced martensite transformation of 301 stainless steel during cold rolling has been simulated by ANSYSsoftware. First, the mesh sensitivity analysis was performed and mesh optimization was set to stimulate the straininduced martensite transformation of 301 stainless steel during cold rolling. Martensite fractions in cold-rollingwas simulated and compared with experimental data. Finite element analysis was performed to obtain strain andstress during cold rolling. The amount and distribution of martensite during cold rolling has been modeled. Thehighest stress level was observed and applied on a friction plate which was in contact with rollers and, as aresult, was under the most friction; thus, the stress reduced away from the surface toward the center of the sheet.Moreover, a similar phenomenon was observed for changes in the strain. These results were also compared withexperimental data that had been obtained with X-ray diffraction, with the use of a Ferritoscope, X-ray diffractionand experimental results.
Cold rolling
Austenitic stainless steel
Martensite transformation
Finite element
Stress-strain
2016
12
01
26
30
https://journal.issiran.com/article_23710_ecffbe6417ee96c8baf65efbdebdcaa8.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
Preparation and Mechanical Properties of Nano/Ultrafine Bainitic Structure in AISI 52100 Steel
M.
Tavoosi
M.
Nourbakhsh
S.R.
Hosseini
The development of nano/ultrafine bainitic structure in AISI 52100 steel was the goal of this study. For this purpose,the AISI 52100 the specimens were austenitized at 1050 °C for 60 min followed by low-temperature austemperingtreatment at different temperatures and times. The austempered samples were characterized using field emissionscanning electron microscopy (FESEM), X-ray diffraction (XRD) and tension test. According to achieved results,the microstructure of AISI 52100 steel after the austempering treatment consisted of ultrafine bainitic ferrite platesand retained austenite with two morphologies of micrometer-block and fine film. At the austempering temperatureup to 250 °C, the micrometer-blocky morphology of austenite completely vanished from the microstructure, andthe strength and ductility increased to about 2000 MPa and 7 %, respectively. By increasing the austemperingtemperature to 300 °C, the strength and ductility reduced (to about 1808 MPa and 3 %) simultaneously as a resultof changing in the shape and size of bainite phase.
Nanostructures
52100 steel
X-ray diffraction
Mechanical properties
2016
12
01
31
39
https://journal.issiran.com/article_23711_80029ddd3acec9b7c0f3224e548d9910.pdf
International Journal of Iron & Steel Society of Iran
Int. J. of ISSI
2981-0388
2981-0388
2016
13
2
A Statistical Analysis of the Mechanical Properties of the Beam 14 in Lines 630 and 650 of Iran National Steel Industrial Group
B.
Mansouri
H.
Montazer Hojat
Structural steel sections are mainly used in beams and columns of building frames. Iran National Steel IndustrialGroup is among the oldest and largest producers of beams in Iran. It has two beam production lines, namely Line630 and Line 650. In this study, the mechanical properties of manufactured beams in these production lines werecompared. Based on the t-test results, the elongation is significantly higher in Line 650 products while tensilestrength is higher in Line 630. However, the two lines do not show any significant differences in the yield stress.Mann-Whitney test was also used to determine if one of the mechanical properties significantly differs in the twolines products. Based on the test, the tensile strength, elongation and yield stress were significantly different inthe two production lines. According to the Levene and Fisher test, Line 650 products were more homogeneousin terms of the tensile strength and yield stress while Line 630 products were more homogeneous with regardto elongation. Moreover, the length of the production line and the cooling time seem to affect the mechanicalproperties. In addition, an inverse relationship between tensile strength and beam elongation was observed in thisstudy.
Beam
Mechanical properties
Student's t tests
Mann-Whitney test
Levene test
2016
12
01
40
45
https://journal.issiran.com/article_23713_1b337fd4f9e42cec1f8be054dfaf0984.pdf