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Iron and steel society of Iran - Volume:15 Issue: 1, Summer and Autumn 2018

International Journal of iron and steel society of Iran
Volume:15 Issue: 1, Summer and Autumn 2018

  • تاریخ انتشار: 1397/03/01
  • تعداد عناوین: 7
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  • H. Mostaan *, M. Poorkabirian, M. Rafiei Pages 1-8
    In this research the interface structure of dissimilar joint between AISI 4130 and AISI31 L steels produced by GTAW process was evaluated. ERNiCr-3 was used as a filler metal for this joint. After welding the microstructure of different areas including weld metals, heat affected zones and interfaces were studied by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) analysis. It was found that the weld metal entirely has astenitic microstructure with relatively equiaxed grains and denderitic morphology. The results also showed that the grain growth in 4130 steel-weld metal interface was unepitaxial due to the severe difference in chemical composition between the base and weld metals. Microhardness measurements showed that the welded sample indicated the highest microhardness in the heat affected zone of 4130 steel because of the presence of tempered matensite and bainite in this area. In the weld zone a decrease in hardness value from AISI 4130 steel to AISI 316L can be seen. This reduction in microhardness can be due to the less amount of carbon in the weld area in vicinity of the AISI 316L base metal.
    Keywords: Dissimilar Joint, GTAW, 316L Steel, 4130 Low alloy steel, ERNiCr, 3, Interface structure
  • M. R. Khanzadeh Gharah Shiran *, H. Bakhtiari, M. M. Ghafari, S. Rajaee, M. Mohammadnejad Pages 9-18
    In the present research, the effect of standoff distance on corrosion properties of the joint of three aluminum–steel explosive layers has been studied. For this purpose, the samples were welded with various standoff distance under constant explosive load. Optical Microscopy and Scanning Electron Microscopy were used to measure the quality of the joint and type of interface. Furthermore, point analysis of EDS was used to study the local and continuous welded areas. In addition, hardness test was employed to investigate the mechanics of the joints, electrochemical polarization and impedance in order to examine the corrosion behavior of various samples. Results of the microstructural investigations have suggested wavy – vortex transition of interface and formation of locally melted areas with a combination of the joined plates as a result of standoff distance and collision kinetic energy augmentation. Results indicated that changes of iron percentage rate in localized fusion areas of the interface had considerable effect on the cathodic behavior and corrosion caused by the galvanic cell of the interface. Moreover, the increase of collision kinetic energy in the interface led to a decrease in corrosion resistance in the impedance test.
    Keywords: Collision kinetic energy, Explosive welding, Galvanic couple, Standoff distance, Local fusion areas
  • S. Abdi, I. Ebrahimzadeh * Pages 19-27
    As an important problem in forging factories, dies are destroyed because of high wear rate, plastic deformation and thermal and mechanical fatigue at high temperatures. This paper is an investigation into the use of nickel super alloy with different welding parameters. Three weld overlaid alloys of inconel625, as wear resistance hardfacing materials on H13 tool steel, with different welding parameters were deposited on H13 steel substrates using the tungsten inert gas welding process. Dilution, microstructures and microhardness of the weld overlays were obtained at room temperature. Wear tests were carried out using the pin-on-disk wear tester at room temperature and 550 °C. The wear surfaces were examined by scanning electron microscopy (SEM). The results showed a much lower wear at high temperature with the weld overlays welded under the pulse condition. In the performance tests, a better die life behavior was observed by using a die coated with Inconel625. The die life in the hot forging of production was increased by 86%, as compared to AISI H13 steel.
    Keywords: Wear, hardfacing, Inconel625, AISI H13, Welding
  • M. Zamani, H. Mirzadeh *, M. Maleki, F. Jamei Pages 28-32
    The effect of the initial microstructure and intercritical annealing on mechanical properties and work-hardening response of a high-formability low carbon steel were studied. The work-hardening analysis was based on the modified Crussard–Jaoul method. The ferritic-pearlitic sheets showed low strength and high total elongation with the appearance of the yield point phenomenon. The occurrence of yield-point phenomenon resulted in the very low work-hardening rates at the initial stages of deformation. However, after intercritical annealing, a good combination of tensile strength and ductility along with much better work hardening response was observed. Intercritical annealing of martensite initial microstructure was found to be a viable technique for graining refinement of DP steels with much better tensile strength compared with that obtained by intercritical annealing of the normalized microstructure. These observations were related to the much finer microstructure and enhancement of work-hardening behavior in the former, where its work-hardening rate at each given true stress was considerably higher.
    Keywords: Dual phase steels, Initial microstructure, Mechanical properties, Strain hardening rate
  • M. Safari *, J. Joudaki, M. Emadi Pages 33-39
    Lubricant and coolant can improve surface roughness in machining. In addition of ecological harms, thermal shock of coolant or lubricant may affect the surface integrity especially on surface residual stresses and micro-crack nucleation. Dry machining is ecologically desirable and it is considered as a necessity for manufacturing enterprises in the recent years. 55Cr3 steel grade is steel with high strength and very poor machinability. Therefore dry machining can provide good surface qualities in turning process of 55Cr3 steel bars. In this article, the effects of turning parameters (spindle speed, feed and depth of cut) on surface roughness variation will be investigated. The surface roughness was measured in straight turning and face turning processes. The Taguchi method was implemented for experiments designing and analyzing the measurements. The results showed that in order to obtain an optimum condition for dry turning of 55Cr3 steel bars, Ra, Rq, Rt, RSm and RSk should be analyzed simultaneously.
    Keywords: Dry machining, Surface quality, 55Cr3 steel, Design of experiments
  • P. Jafari Fesharaki * Pages 40-48
    Industrial growth and environmental damages, as two important indicators in sustainable development are followed by steel industry. This article leads industries to green industry. In this case, energy, material, capital consumption and environmental damages as sustainability patterns of environment have been investigated in three different dust collectors to select the most environmentally suitable dust collector for different furnace tonnages. In this way total cost in 3 mentioned dust collectors were calculated in four furnaces with capability of 1, 3, 6 and 12 tonnages. The results indicated that venturi scrubber dust collector for 3-ton and less capability furnaces was the most suitable option in terms of environmental sustainability and industrial ecology. But for the capacities beyond 3 tons, the usage of bag filters and electrostatic precipitator dust collectors were more suitable.
    Keywords: Dust collector, Steel industry, Energy, Industrial ecology, Cost
  • M. Tayyebi, F. Ghanbari *, A. Kumar Pages 49-53
    The method of continuous casting of steel is now often used in the metallurgical industry, due to the increasing demand for the production of high – quality steel. An important device of continuous casting machine is the tundish, in which a stabilized steel flow has a crucial effect on the quality and efficiency conditions of the continuous casting process. In this study fluid flows in a six – strand tundish for billet continuous casting were performed with mathematical simulation methods. The molten steel flow and velocity fields in the tundish with a turbulence inhibitor, without it and with turbulence inhibitor plus weir in different distance from center were numerically calculated. Simulation results showed that the tundish with turbulence inhibitor and weir in 300 mm distance from center has a significant effect on the flow fields of the tundish. Also the results showed inclusion removal increases by producing a uniform flow field with re-circulatory zone away from the nozzles. It can be seen that circulation region is produced in the all tundish models. However, in case of using tundish without turbo stop, it increased in comparison to others.
    Keywords: Fluid flows, Tundish, Turbulence inhibitor, Weir, Mathematical simulation