ORIGINAL_ARTICLE
The Effect of Inclusions on Through-thickness Directional Fatigue Behavior of S355N Steel Plate
Microalloyed S355N steel plates are extensively used in bridge and high-rise building structures. One of the factors affecting the mechanical properties is the size and morphology of inclusions. In this research, microalloyed S355N steel plates with different sizes of inclusions were examined. One contained long manganese sulfide inclusions (LI material) and the other had short ones (SI material). Fatigue and tensile tests were carried out in through-thickness direction of both materials. Additionally, the fatigue test results were verified by “statistics of extreme value” (SEV) method. The tensile and fatigue tests revealed that toughness and fatigue limit of LI material were 65% and 30% less than those of SI, respectively. The SEV analysis conservatively predicted the fatigue limit of SI material. However, it was not accurate enough in the case of LI. These results could be explained using the behavior of manganese sulfide inclusions as short fatigue cracks in steels.
https://journal.issiran.com/article_12092_4be333e1f799674b36b460c03936cca5.pdf
2015-03-01
1
6
fatigue
Through-thickness direction
Non-metallic inclusion
Short fatigue crack
Statistics of extreme
value
A.
Abyazi
a_abyazi@sut.ac.ir
1
Faculty of Materials Engineering, Sahand University of Technology, Tabriz, 5331711111, Iran
LEAD_AUTHOR
A.
Ebrahimi
2
Department of Mining and Metallurgical Engineering, Amirkabir University of Technology, Tehran, 158754413, Iran
AUTHOR
ORIGINAL_ARTICLE
The Effect of Intercritical Annealing Time on the Microstructures and Mechanical Properties of an Ultrafine Grained Dual Phase Steel Containing Niobium
An ultrafine grained dual phase (UFG DP) steel containing niobium was produced by a new route utilizing simple cold-rolling and subsequent intercritical annealing of ferrite/martensite duplex starting structures. The effects of intercritical holding time on the microstructural evolutions and mechanical properties were studied. The results showed that increasing intercritical holding time enhnaced the volume fraction of martensite and decreased the grain size of ferrite. Tensile testing also revealed good strength–elongation balance for UFG DP steels (UTS×UE > 100 Jcm-3), in comparison with the commercially used high strength steels. The variations of strength, elongation and fracture behavior with intercritical holding time were correlated with the microstructural features.
https://journal.issiran.com/article_12093_fddb21a5dc667cceeb64130090e6e06b.pdf
2015-03-01
7
11
dual phase steel
Cold-rolling
Intercritical annealing
Mechanical characterization
Fracture behavior
A.
Ghatei Kalashami
a.ghatei@ma.iut.ac.ir
1
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
LEAD_AUTHOR
A.
Kermanpur
ahmad_k@cc.iut.ac.ir
2
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
AUTHOR
A.
Najafizadeh
abbas.najafizadeh@gmail.com
3
Fould Institute of Technology, Fouldshahar, Isfahan, 8491663763, Iran
AUTHOR
Y.
Mazaheri
4
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
AUTHOR
ORIGINAL_ARTICLE
A Predictive Model Accounting for the Mechanical Behavior of Galvanized Alloy Layers on the Mild Steel
Zinc coating is formed by the heterogeneous assembly of the Γ, Γ1, δ, ζ and η phases whose mechanical properties greatly differ from each other. Thermal strains resulting from large differences between thermal expansion coefficients are partially relaxed by the formation of a crack network. In order to model this phenomenon, initial hardness, thermal expansion coefficient αi and toughness (KIC) of the phases were determined. Hardness testing experiments performed on the galvanizes samples with and without annealing revealed that during the cooling down of the samples in the coating process, there was some residual stress in the coating due to the difference between the thermal expansion coefficients of the phases. In this regard, maximum hardness, 340 HV, was obtained for δ phase and its toughness was measured to be about 2MPa√m, thereby revealing that δ phase was completely brittle compared to other phases. Modeling the behavior of the phases present in the coating demonstrated that during the cooling stage, at first, some micro-cracks were formed in δ phase and grew in two stages: I) perpendicular to the δ/α interface and II) parallel to the δ/α interface. The results revealed that when the thickness of δ phase was more than 5μm, there was a good agreement between the experimental results and the proposed model. Also, due to the properties of the coating layers, the resulted stresses could not delaminate the coating.
https://journal.issiran.com/article_12094_86d0d895cd99fbcf2488f3c3526a8b7c.pdf
2015-03-01
12
17
Modeling
Galvanizing
Intermetallic
Alloy layers
Toughness
Residual Stress
H.
Sharifi
sharifi@eng.sku.ac.ir
1
Faculty of Engineering, Shahrekord University, Shahrekord, Iran
LEAD_AUTHOR
ORIGINAL_ARTICLE
A Study of Precision Forging of Steel Spur Gears: Upper Bound Model and Experiments
Precision forging process is widely used for the production of spur gears due to its advantages such as improved strength and surface finish, little waste of materials and reduction in the machining time of the gear. An important aspect of precision forging process is the load required to perform the process successfully and design the forging tools. In this research, a new kinematically admissible velocity field was presented to predict the precision forging pressure of the steel spur gear by upper bound analysis. The model considered the shape of tooth profile, the number of teeth and friction coefficient. The accuracy of the model was verified using experimental results and a good agreement was found between the two sets of results at the filling stage of the precision forging process. Also, the results were compared with the models developed by other researchers, showing that the teeth profile considered in this study was much closer to the actual profile of the gear.
https://journal.issiran.com/article_12096_c7a4bc9edd7ddf59ca9d4ef4a25c50e9.pdf
2015-03-01
18
23
Steel
Precision forging
Upper bound method
Spur gear
M.
Irani
irani@gut.ac.ir
1
Department of Materials Science and Engineering, Golpayegan University of Technology, Isfahan, Iran
LEAD_AUTHOR
R.
Amini Najafabadi
2
Department of Materials Science and Engineering, Golpayegan University of Technology, Isfahan, Iran
AUTHOR
T.
Dallali Isfahani
3
Department of Materials Science and Engineering, Golpayegan University of Technology, Isfahan, Iran
AUTHOR
ORIGINAL_ARTICLE
Application of Response Surface Methodology to Assess the Combined Effect of Operating Variables on the Direct Reduction of Fe2O3 by Coal Volatiles
The reduction of Fe2O3 powder at the top layer by the volatiles from high volatile (HV) bituminous coal at the bottom layer of a multilayer powder geometry including a separating alumina layer was studied. The simultaneous effects of the alumina layer thickness, time, temperature and the weight of coal on the amount of reduction and coal devolatilization were studied by implementing a rotatable central composite design (CCD) based on response surface methodology (RSM). RSM successfully revealed the influential operating variables and the effects of the interactions between the variables on the reduction of Fe2O3 and devolatilization of coal. The phase evaluation of various iron oxide phases and metallic iron was obtained through XRD. The XRD results showed that the reduction of pure Fe2O3 to metallic iron proceeded through a stepwise reduction via Fe3O4 and FeO. It was also found that the reduction of iron oxide by coal volatiles occurred internally uniformly at the first stage of reduction to form Fe3O4; however, the behavior became nearly topochemical as the reduction proceeded.
https://journal.issiran.com/article_12097_1e777c5ccdaaf68794e333ea04b62f81.pdf
2015-03-01
24
30
Coal volatile
Iron oxide reduction
Response surface methodology
Analysis of variance
M.
Zare
mansoor.zare18@gmail.com
1
Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
LEAD_AUTHOR
J.
Vahdati-Khaki
2
Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
AUTHOR
A.
Zabet
3
Department of Materials Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran.
AUTHOR
ORIGINAL_ARTICLE
Microstructural Evolution of X45CrNiW189 Valve Steel During Hot Deformation
The hot compression tests were carried on X45CrNiW189 valve steel (X45) in the temperature range of 1000– 1200 °C and the strain rate range of 0.004 – 0.5 s-1 in order to study the high temperature softening behavior of this steel. For the exact prediction of flow stress, the effective stress-effective strain curves were obtained from experiments under various conditions. On the basis of experimental results, the dynamic recrystallization fraction (DRX), austenite grain size (AGS), hot deformation and activation energy behavior were investigated. It was found that the calculated results were in a good agreement with the experimental flow stress and the microstructure of the steel for different conditions of hot deformation.
https://journal.issiran.com/article_12098_58b776bed2c96ec8d3cacd7be149535d.pdf
2015-03-01
31
34
X45CrNiW189
Valve
compression
Recrystallization
deformation
A.
Meysami
amirhossein.meysami@gmail.com
1
Metallurgy & Material Dept., Golpayegan University of Technology, P.B.: 87717-65651, Golpayegan, Iran.
LEAD_AUTHOR
R.
Amini Najafabadi
2
Metallurgy & Material Dept., Golpayegan University of Technology, P.B.: 87717-65651, Golpayegan, Iran.
AUTHOR
ORIGINAL_ARTICLE
The Effect of Chloride Ions Concentration on the Electrochemical Behavior of AISI 410 Stainless Steels in Simulated Concrete Pore Solution
The effect of chloride ions concentration on the electrochemical behavior of AISI 410 stainless steel in the simulated concrete pore (0.1 M NaOH + 0.1 M KOH) solution was investigated by various electrochemical methods such as Potentiodynamic polarization, Mott–Schottky analysis and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves revealed that increasing chloride ions concentration led to decreasing the corrosion and pitting potentials of AISI 410 stainless steel. Mott– Schottky analysis demonstrated that passive films formed on AISI 410 stainless steel in the simulated concrete pore solution with and without NaCl addition showed some n-type semiconducting behavior in nature. Moreover, Mott–Schottky results showed that the donor density was increased by increasing chloride ions concentration. EIS revealed that in the absence of chloride ions, the surface films formed on AISI 410 stainless steel in the simulated concrete pore showed higher passive film and charge transfer resistance. However, in the presence of chloride ions, an inversion of this trend was observed.
https://journal.issiran.com/article_12099_acf4cb91b1dac4ecb74537ed060d338e.pdf
2015-03-01
35
40
AISI 410 stainless steel
Chloride ion
Concrete
Polarization
A.
A.
a.fattah@basu.ac.ir
1
Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695, Iran
LEAD_AUTHOR
M.
Hojati Fahim
2
Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695, Iran
AUTHOR
E.
Nikomanzari
3
Department of Materials Engineering, Bu-Ali Sina University, Hamedan 65178-38695, Iran
AUTHOR