فهرست مطالب

Iron and steel society of Iran - Volume:13 Issue: 1, Winter and Spring 2016

International Journal of iron and steel society of Iran
Volume:13 Issue: 1, Winter and Spring 2016

  • تاریخ انتشار: 1395/05/18
  • تعداد عناوین: 7
|
  • A. H. Madadian, H. Najafi *, M. A. Safarkhanian, S. Nategh Page 1
    Mechanical properties of dissimilar weld joints between GOST09ch16N4B (a martensitic stainless steel) and AISI 4130 thin sheets made by gas tungsten arc welding (GTAW) were studied using ER410NiMo and ER100S-G filler metals in post weld heat treated conditions. Heat treatment cycles consisted of austenitization at 900, 950 and 1000 °C for 1 h and this was followed by oil cooling and tempering at 400 and 500 °C for 1 h. Tensile tests and microhardness measurements were carried out to evaluate the mechanical properties. The base metals, heat affected zones (HAZs) and fusion zones were observed by optical microscope and scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS). Based on the results, it was found that the joints strength and microhardness profiles were almost independent of austenitization temperature, but they were affected by the tempering temperature. Increasing the tempering temperature led to the reduction in the hardness of AISI 4130 and the joints strength. Tensile samples were fractured in the base metals. Furthermore, the fracture was shifted from GOST09ch16N4B to AISI 4130 with increasing the tempering temperature. Crack initiation from delta-ferrite led to the fracture in GOST09ch16N4B. Strength and elongation obtained from different PWHTs indicated that tempering at 400 °C resulted in acceptable tensile properties for the weldments made with both filler metals.
    Keywords: GOST09ch16N4B, AISI 4130, Dissimilar Welding, GTAW
  • H. Sharifi *, M. Salehi, T. Dallali Isfahani, H. Rafiei Borujeni Page 8
    The aim of this research was to study the wear behavior of 42CrMo4 steel/ZrO2 composite with 10 and 30 ppi performed ceramic and compare it with the un-reinforced steel under different applied loads. The composite specimens were obtained by pressureless infiltration of the melt into a preformed ceramic of zirconium oxide. The effect of applied load on the specimens wear behavior was studied by applying the wear test under loads of 90, 120 and 150 (N). The results indicated that at the applied loads, the reinforcement and the increase of volume fraction considerably improved the specimens wear behavior. Furthermore, the microscopic images showed that the increase in force resulted in a change in the wear mechanism of the steel and the 10ppi composite from an abrasive to an adhesive one, while the wear mechanism of the 30ppi composite remained unchanged as abrasive.
    Keywords: Wear, Composite, 42CrMo4 steel, ZrO2, Pressureless infiltration
  • M. Rakhshkhorshid, H. Rastegari * Page 15
    Many efforts have been made to model the the hot deformation (dynamic recrystallization) flow curves of different materials. Phenomenological constitutive models, physical-based constitutive models and artificial neural network (ANN) models are the main methods used for this purpose. However, there is no report on the modeling of warm deformation (dynamic spheroidization) flow curves of any kind of steels. In this work, a neural network with feed forward topology and Bayesian regularization training algorithm was used to predict the warm deformation flow curves of a eutectoid steel. The experimental data was provided by sampling the dynamic spheroidization flow curves of the tested steel obtained from warm compression tests conducted over a temperature range of 620-770 °C with different strain rates in the range of 0.01-10 s-1. To develop the neural network model, the overal data was divided into three categries of training, validation and testing. The scatter diagrams together with the root mean square error (RMSE) criterion were used to evaluate the prediction performance of the developed model. The low calculated RMSE value of 4.15 MPa for the overall data showed the robustness of the developed ANN model in predicting the warm deformation flow curves of the tested steel. The results can be further used in the mathematical simulation of warm metal forming processes.
    Keywords: Warm deformation, Flow stress, Artificial neural network model, Dynamic spheroidization
  • A. Shafieirad, A. Arefpour*, A. Monshi, A. Saidi Page 20
    Mold powders used in the continuous casting of steel contain the harmful CaF2 as a main substance developing toxic gases such as SiF4 and HF at elevated temperatures. In this study, three samples of I1, I2 and I3, which contained gypsum free Portland cement clinker with different percentages of Fe2O3 (5.68, 6.83, 8.02 ) and F- (2.09, 1.06, 0), were prepared and their main characteristics were compared with those of the standard and the molten reference powder. The results showed similarity in viscosity between samples I1, I2 and the molten reference powder, which was desired. Sample I3 with no fluorine showed a higher viscosity in comparison to the standard sample and therefore, a complete replacement of CaF2 with Fe2O3 could not be recommended. Furthermore, the XRD of the reference powder, molten reference powder and sample I2, the SEM of the molten reference powder and sample I2 and EDS of sample I2 analyses were also performed. The XRD patterns results demonstrated that by decreasing CaF2, cuspidine phase was vanished, while other crystalline phases such as gehlenite, fayalite, akermanite, nepheline and Mn3O4 were found. In addition, SEM micrographs and EDS analysis of sample I2 in the white area revealed crystalline particles in the glass matrix. Considering EDS analysis of sample I2 showed the existence of Mg, Na, Mn, Fe, Si, Al and O. It could be concluded that such crystals as gehlenite, akermanite, nepheline and fayalite were composed in the glass matrix, developing to similar heating properties in the glassy matrix.
    Keywords: Mold powder, Viscosity, Fluorine, Hematite
  • S. Zarei, R. Jafari Nedoushan* Page 27
    The microstructure of dual phase steels can be considered as a matrix of ferrite phase reinforced by martensite particles. Recent measurements show that the mechanical properties of the ferrite phase are changed with the distance from the martensite grains. In this paper, a new method has been proposed to consider this phenomenon in finite element modeling of dual phase steels microstructure. In this method, ferrite mechanical properties were imported to the model as a continuous function of the distance from martensite boundary. A unit cell model of dual phase steel was constructed based on the experimental measurements. The tensile test was simulated in both cases of considering the ferrite phase as the homogeneous and inhomogeneous matrix. It was observed that by considering the ferrite phase inhomogeneity, the model could predict macro stress precisely. Considering the ferrite phase inhomogeneity also led to the better prediction of shear band formation in the unit cell, as compared to the other model. A different stress distribution prediction was also observed in these two models and ferrite phase maximum stress was higher when inhomogeneity was included. These observations could be crucial in the investigation of dual phase steels damage. It was observed that martensite volume fraction and the grain size had a stronger effect on the model with the inhomogeneous ferrite phase.
    Keywords: Dual phase steels, Finite element microstructural modeling, Ferrite phase inhomogeneity
  • H. R. Akramifard, H. Mirzadeh*, M. Habibi Parsa Page 39
    The cold roll bonding of Al on AISI 304L stainless steel was carried out to fabricate the Al 304L/Al clad sheet composites. The maximum bond strength of 20 N/mm was acquired just by 38% reduction, for which the tearing of the aluminum sheet occurred during the peeling test. The microstructural evolution during subsequent postannealing heat treatment was systematically studied based on the impurity diffusion coefficients, microhardness measurements, X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM) images and energy dispersive X-ray analysis (EDS) spectra to pave the way for successful applications of these composite sheets. An intermediate layer composed of intermetallics of Al and Fe was found to form on the aluminum side of the roll bonded sheets, showing that this layer was formed by the diffusion of elements from the 304L sheet to the aluminum sheet due to the faster diffusion of Fe in Al. Moreover, the calculated diffusion distances were in a good agreement with the results obtained from the line scan EDS analysis and the microhardness profile. It was also found that the presence of the strain-induced martensite in the 304L sheet did not exert any effect on the intermediate layer.
    Keywords: Cold roll cladding, Heat Treatment, Peel Test, Diffusion, Intermetallic compounds
  • A. Fattah, Alhosseini *, B. Hamrahi Page 46
    In this work, electrochemical methods such as Tafel polarization and electrochemical impedance spectroscopy (EIS) were used to study the inhibition efficiency of Nettle leaves hydroalcoholic extract as a green corrosion inhibitor of API 5L carbon steel in 0.5 M H2SO4 solution. The results showed that the inhibition efficiency was increased with increasing the concentration of the extract and the maximum inhibition efficiency in the concentration of 6 g/L was 96%. The negative sign 0 ΔGads absorption of inhibitor on the steel surface was spontaneous and the value 0 ads ΔG represented the physical absorption of the inhibitor which followed the Langmuir isotherm.
    Keywords: API 5L carbon steel, Nettle extract, EIS, Langmuir isotherm