Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201Investigation of influences of alloying elements and sintering temperature on the properties of high strength low alloyed sintered steelInvestigation of influences of alloying elements and sintering temperature
on the properties of high strength low alloyed sintered steel156337ENM. AzadbehDepartment of Materials Engineering, Sahand University of Technology, Tabriz, Iran,P.O.Box 51335-1996N. PeyghambardoustDepartment of Materials Engineering, Sahand University of Technology, Tabriz, Iran,P.O.Box 51335-1996VM. MohammadpourDepartment of Materials Engineering, Sahand University of Technology, Tabriz, Iran,P.O.Box 51335-1996A. KalantariDepartment of Materials Engineering, Sahand University of Technology, Tabriz, Iran,P.O.Box 51335-1996Journal Article20140701Producing parts with high density and improved mechanical properties is one of the most important aims of powder metallurgy process. There are many factors for attaining modified properties in sintered parts but among them controlling type and quantity of alloying elements and manufacturing parameters such as compacting pressure, sintering temperature are the most effective. In this research, two series of Cr-Mo prealloyed powders with 1.5% and 3% chromium contents were used, and then influences of manufacturing parameters on physical and mechanical properties were investigated. The results show that by compacting pressure and sintering temperature increment and chromium content decrement, density is increased and subsequently physical and mechanical properties of low alloyed sintered steels are improved.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201The effects of chemical composition variations on microstructure and mechanical properties of nanostructured, low temperature bainitic steelsThe effects of chemical composition variations on microstructure and mechanical properties of nanostructured, low temperature bainitic steels6116338ENM. N.YoozbashiFaculty of Materials Engineering, Sahand University of Technology, Tabriz, IranS. YazdaniFaculty of Materials Engineering, Sahand University of Technology, Tabriz, IranT. S.WangState Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, ChinaJournal Article20140701Bainitic transformation at low transformation temperatures leads to a microstructure involving fine plates of bainitic ferrite and thin films of retained austenite. This microstructure has shown ultimate tensile strength of about 2.2 GPa, noticeable uniform elongation in the range of 5 to 30%, hardness values of about 600 to 670 HV and impact toughness in the range of 30 to 40 MPa m1/2. With careful design of the chemical composition of steel, suitable mechanical properties with lower cost production could be achieved. In the current work, the microstructure and mechanical properties of two steels with different chemical compositions have been evaluated using XRD, SEM, TEM, tensile and Charpy impact tests. The results of this study suggest that without trial and error, it is possible to design a new steel with unique microstructure and mechanical properties. The achieved mechanical properties are due to the microstructural characteristics which evolved during isothermal transformation.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201The effect of deep cryogenic treatment on mechanical properties of 80CrMo12 5 tool steelThe effect of deep cryogenic treatment on mechanical properties of 80CrMo12 5 tool steel12176339ENK. AminiDepartment of Materials Engineering, Science and Research Branch, Islamic Azad University (IAU), Tehran, IranS. NateghDepartment of Materials Engineering, Science and Research Branch, Islamic Azad University (IAU), Tehran, IranA. ShafyeiDepartment of Materials Engineering , Isfahan University of Technology, Isfahan, IranA. RezaeianDepartment of Materials Engineering , Isfahan University of Technology, Isfahan, IranJournal Article20140701Cryogenic treatment can be used as a supplemental treatment that is performed on some tool steels between quenching and tempering as an effective method for decreasing retained austenite and increasing wear resistance. In this research, the effect of deep cryogenic treatment (DCT) on dimensional stability and mechanical properties of 80CrMo12 5 tool steel was investigated. The martensitic transformation start and finish temperatures were also studied using dilatometry tests. The results show that the start and finish temperatures of the martensitic transformation are 254°C and - 87°C, respectively. The hardness increases (untempered) by 3 HRC after DCT. Thus, to decrease or eliminate the amount of retained austenite, cryogenic treatment is necessary. In DCT, impact energy and hardness at all tempering temperatures decreases and increases, respectively. Tempering transformations investigation using dilatometry tests, verified that the DCT increases dimensional stability. This is attributed to the transformation of retained austenite to martensite.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201X-ray diffraction peak profile analysis of maraged Fe-Ni-Mn steelsX-ray diffraction peak profile analysis of maraged Fe-Ni-Mn steels18206340ENF. Hosseini NasabFaculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz, IranS. Hossein NedjadFaculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz, IranM. R.Movaghar GarabaghFaculty of Materials Engineering, Sahand University of Technology, P.O. Box 51335-1996, Tabriz, IranJournal Article20140701X-ray diffraction peak profile analysis was used to identify changes in the lattice distortions during isothermal aging of Fe-10Ni-7Mn (wt. %) maraging steel. Integral peak breadths were analyzed using classical Williamson-Hall equation taking the elastic anisotropy into account. It was found that substantial lattice distortions rise during precipitation hardening which depend strongly on the specific Young’s modulus of a given crystallographic direction. After normalizing by elastic stiffness, the magnitude of average lattice distortions increased reasonably in accordance with age hardening.X-ray diffraction peak profile analysis was used to identify changes in the lattice distortions during isothermal aging of Fe-10Ni-7Mn (wt. %) maraging steel. Integral peak breadths were analyzed using classical Williamson-Hall equation taking the elastic anisotropy into account. It was found that substantial lattice distortions rise during precipitation hardening which depend strongly on the specific Young’s modulus of a given crystallographic direction. After normalizing by elastic stiffness, the magnitude of average lattice distortions increased reasonably in accordance with age hardening.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201Evaluation of microstructure and mechanical properties of friction stir welded copper / 316L stainless steel dissimilar metalsEvaluation of microstructure and mechanical properties of friction stir welded copper / 316L stainless steel dissimilar metals21256341ENA. NajafkhaniDepartment of Materials Engineering, MUT, Tehran 15875-1774, IranK. Zangeneh-MadarDepartment of Materials Engineering, MUT, Tehran 15875-1774, IranH. AbbaszadehDepartment of Materials Engineering, MUT, Tehran 15875-1774, IranJournal Article20140701In the present research, friction stir welding (FSW) process was used for butt joining of pure copper plate to 316L stainless steel plate. Mechanical properties and microstructural characteristics of the joint were evaluated by microhardness and tensile tests as well as optical and scanning electron microscope (SEM). It was found that microstructure of the weld nugget (WN) has fine grains whereas the elongated grains are located in the thermo mechanically affected zone (TMAZ) into 316L stainless steel. Also, coarse grains are observed in the heat affected zone (HAZ) into pure copper. The microhardness values of the WN are much higher than the base metals. The HAZ zone shows minimum hardness values. The butt joint has 85% weld efficiency compared to the copper base meal.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201The effect of mechanical activation on the carbothermic reduction kinetics of hematite-graphite mixtureThe effect of mechanical activation on the carbothermic reduction kinetics of hematite-graphite mixture26336342ENF. MohseniDepartment of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran.M. H.AbbasiDepartment of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran.M. PanjepourDepartment of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111, Iran.Journal Article20140701The effect of mechanical activation on structural changes and kinetics of carbothermic reduction of hematite with graphite was studied in this research. Hematite powder mixture with graphite (with stoichiometry ratio C/O=1) was milled for the time periods of zero to 50 hours, and the structural changes were studied using X ray diffraction (XRD). The effect of mechanical activation on the kinetics of hematite carbothermic reduction was studied by performing thermal analysis tests and by employing model-free and constant slope methods. The activation energy as well as the reaction mechanism was then determined. The results showed that by mechanical activation for a time period of 50 h, the activation energy is decreased from 387 kJ/mol-1 to 186 kJ/mol-1, and the starting temperature of the reaction is decreased from 1125 to 620°C. The Boudouard chemical reaction was determined as the rate controlling step.Iron & Steel Society of IranInternational Journal of Iron & Steel Society of Iran2981-03887220101201A simple Analytical model for solidification cooling rate based on the local heat flux densityA simple Analytical model for solidification cooling rate based on the local heat flux density34446343ENM. AlizadehDepartment of Metals, International Center for Science, High Technology & Environmental Sciences,Kerman,Iran.S. Jenabali-JahromiScience and Engineering, Shiraz University, Shiraz, Iran.Journal Article20140701A new simple analytical model for prediction of cooling rate in the solidification process based on the local heat flux density extracted during solidification is introduced. In the modeling procedure, a solidifying control volume is considered in the mushy zone in which a heat balance equation is used to derive the present model. As the local heat flux density is a measurable parameter, the present model can be used directly on a production line. The present model was validated with numerical method and well adopted with analytical model of Garcia et al. The validation depicted that the present model can predict the cooling rate during solidification process with the same accuracy of the numerical method and Garcia’s model. Moreover, it was shown that the present model can be used to calculate the average and local cooling rate, where the available models face some difficulties.