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| 1 | Effects of Silicon Content and Intercritical Annealing on Manganese Partitioning in Dual Phase Steels显示文摘Steels of constant manganese and carbon contents with silicon content of 0.34%-2.26% were cast.The as-cast steels were then hot rolled at 1100 ℃ in five passes to reduce the cast ingot thickness from 80 to 4 mm, air cooled to room temperature and cold rolled to 2 mm in thickness. Dual phase microstructures with different volume fraction of martensite were obtained through the intercritical annealing of the steels at different temperatures for 15 min followed by water quenching. In addition to intercritical annealing temperature, silicon content also altered the volume fraction of martensite in dual phase steels. The partitioning of manganese in dual phase silicon steels was investigated using energy-dispersive spectrometer (EDS). The partitioning coefficient, defined as the ratio of the amounts of alloying element in the austenite to that in the adjacent ferrite, for manganese increased with increasing intercritical annealing temperature and silicon content of steels. It was also found that the solubility of manganese in ferrite and austenite decreased with increasing intercritical temperature. The results were discussed by the diffusivity and the solubility of manganese in ferrite and austenite existed in dual phase silicon steels. | A Nouri H Saghafian Sh Kheirandish | 2010 | Journal of Iron and Steel Research(International)2010，17，5： | 21 |
| 2 | Effect of Bainite Morphology on Mechanical Properties of the Mixed Bainite-martensite Microstructure in D6AC Steel显示文摘The effect of bainite morphology on mechanical properties of the mixed bainite-martensite microstructure in D6AC low alloy ultra-high strength steel has been studied in the present work. For this purpose, samples austenitized at 910 C for 40 min were quenched in three different ways. Some of the samples were directly oil-quenched, some others were quenched in salt bath at 330 C and the remaining samples were quenched in salt bath at 425 C for various holding times. All samples were tempered at 200 C for 2 h. Microstructures were examined by optical microscopy (OM) and scanning electron microscopy (SEM). Fracture surfaces also were studied by SEM. Results showed that the mixed microstructure containing martensite and 28 vol.% of the lower bainite exhibited higher yield and tensile strengths than the fully martensitic microstructure. This could be mainly attributed to the partitioning of the prior austenite grains by the lower bainite and enhancing the strength of lower bainite in the mixed microstructure by plastic constraint. Charpy V-notch (CVN) impact energy and ductility were improved by increasing the volume fraction of the lower bainite. This is not the case about the mixed microstructure containing the upper bainite and martensite. As a result, the tensile and CVN impact properties of mixed upper bainite-martensite microstructure are lower than those of the fully martensitic microstructure. Finally, fractography studies showed cleavage fracture at the surface of CVN impact specimens with martensitic and upper bainitic microstructures confirming the tendency to brittle behavior. | Khodamorad Abbaszadeh Hassan Saghafian Shahram Kheirandish | 2012 | Journal of Materials Science & Technology2012，28，4： | 20 |
| 3 | Effect of Heat Treatment on Microstructure of Modified Cast AISI D3 Cold Work Tool Steel显示文摘The effects of heat treatment on the microstructure of modified cast high chromium high carbon AISI D3 steel were studied.The modified AISI D3 steel was developed by replacing part of chromium with niobium and titanium,in which chromium carbide was partially replaced with MC carbides.The cast samples produced by investment casting were heat treated under different conditions.The microstructures of the samples were studied by optical microscope and scanning electron microscope equipped with EDS analyzer.To determine the optimized homogenizing process,the effects of homogenizing treatment on the microstructure and the morphology of carbides were also studied.The results show that the MC carbides are not changed in shape and amounts during high temperature homogenizing,whereas the M3C carbides are reduced in amount and become semiglobular in shape,and the homogeneity of microstructure is improved. | Shahram Kheirandish Hasan Saghafian Jalal Hedjazi Mohammad Momeni | 2010 | Journal of Iron and Steel Research(International)2010，17，9： | 8 |
| 4 | Effects of Austempering and Martempering Processes on Amount of Retained Austenite in Cr-Mo Steels (FMU-226) Used in Mill Liner显示文摘The presence of retained austenite gives rise to deterioration of the wear resistance and fracture strength of Cr-Mo steels in many cases. Thus, the effects of heat treatments including direct quenching, martempering, and austempering on the retained austenite existing in the microstructure of these steels were investigated. Specimens were austenized at 950 ℃ followed by direct quenching using compressed and still air. The specimens were also isothermally quenched in salt bath at 200 and 300 ℃ for 2, 8, 30, and 120 min. Microstructures of the specimens were studied using optical microscope (traditional black and white etching as well as color etching), scanning electron microscope (SEM), microhardness tester, and X-ray diffraction (XRD). The results showed that the lowest amount of retained austenite in the microstructure was obtained in the specimens quenched isothermally at 300 ℃ for 120 min. | M H Shaeri H Saghafian S G Shabestari | 2010 | Journal of Iron and Steel Research(International)2010，17，2： | 8 |
| 5 | Dry Sliding Oxidative Wear in Plain Carbon Dual Phase Steel显示文摘To investigate the tribological potential of the dual phase(DP)steel as a wear resistant material,the wear and the friction characteristics of this steel,which consists of hard martensite islands embedded in a ductile ferrite matrix,have been investigated and compared with those observed in plain carbon hardened(H)steel that has the same carbon content of 0.2%.Dry sliding wear tests have been carried out using a pin-on-disk wear testing machine at different normal loads of 21.3 N,28.5 N,35.7 N,and 42.6 N and at a constant sliding velocity of 1.20 m/s.The analysis of surface and wear debris of samples showed that the wear mechanism was mainly mild oxidative.The friction and the wear rate of the H steel and the DP steel have been explained with respect to the microstructure and the wear mechanism. | V Abouei H Saghafian Sh Kheirandish | 2007 | Journal of Iron and Steel Research(International)2007，14，4： | 3 |
| 6 | Evaluation of TIGGE Ensemble Forecasts of Precipitation in Distinct Climate Regions in Iran显示文摘The application of numerical weather prediction(NWP) products is increasing dramatically. Existing reports indicate that ensemble predictions have better skill than deterministic forecasts. In this study, numerical ensemble precipitation forecasts in the TIGGE database were evaluated using deterministic, dichotomous(yes/no), and probabilistic techniques over Iran for the period 2008–16. Thirteen rain gauges spread over eight homogeneous precipitation regimes were selected for evaluation.The Inverse Distance Weighting and Kriging methods were adopted for interpolation of the prediction values, downscaled to the stations at lead times of one to three days. To enhance the forecast quality, NWP values were post-processed via Bayesian Model Averaging. The results showed that ECMWF had better scores than other products. However, products of all centers underestimated precipitation in high precipitation regions while overestimating precipitation in other regions. This points to a systematic bias in forecasts and demands application of bias correction techniques. Based on dichotomous evaluation,NCEP did better at most stations, although all centers overpredicted the number of precipitation events. Compared to those of ECMWF and NCEP, UKMO yielded higher scores in mountainous regions, but performed poorly at other selected stations.Furthermore, the evaluations showed that all centers had better skill in wet than in dry seasons. The quality of post-processed predictions was better than those of the raw predictions. In conclusion, the accuracy of the NWP predictions made by the selected centers could be classified as medium over Iran, while post-processing of predictions is recommended to improve the quality. | Saleh AMINYAVARI Bahram SAGHAFIAN Majid DELAVAR | 2018 | Advances in Atmospheric Sciences2018，35，4： | 2 |
| 7 | Effect of austempering process on microstructure and wear behavior of ductile iron containing Mn-Ni-Cu-Mo显示文摘 | POURASIABI H M D SAGHAFIAN H POURASIABI H | 2013 | Metals and Materials International2013，19，1： | 1 |
| 8 | Nonlinear transformation of unit hydrograph显示文摘 | SAGHAFIAN B | 2006 | Journal of Hydrology Elsevier2006，330，： | 1 |
| 9 | Time to equilibrium for spatially variable watersheds显示文摘 | SAGHAFIAN B JULIEN P Y | 1995 | Journal of Hydrology Elsevier1995，172，： | 1 |
| 10 | Study on the ability of mechanical vibration for the production of thixotropic microstructure in A356 aluminum alloy 显示文摘 | TAGHAVI F SAGHAFIAN H KHARRAZI Y H K | 2009 | Materials and Design2009，30，1： | 1 |
| 11 | Effect of microstructure on the oxidative wear behavior of plain carbon steel 显示文摘 | V Abouei H Saghafian Sh Kheirandish | 2007 | Wear2007，262，： | 1 |
| 12 | Correlating Mierostruetural Features with Wear Resistance of Dual Phase Steel显示文摘 | Saghafian H Kheirandish S H | 2007 | Ma- terials Letters2007，，6： | 1 |
| 13 | Dry sliding wear behaviour of hypereutectic AI-Si piston alloys containing iron-rich intermetallics显示文摘 | ABOUEI V SHABESTARI S G SAGHAFIAN H | 2010 | Materials Characterization2010，61，： | 1 |
| 14 | Simulation of turbulent flows around a circular cylinder using nonlinear eddy-viscosity modelling: steady and oscillatory ambient flows显示文摘 | Saghafian M Stansby P K Saidi M S Apsley D D | 2003 | Journal of Fluids and Structures2003，17，： | 1 |
| 15 | Study onthe effect of prolonged mechanical vibration on the grain refinementand density of A356 aluminum alloy 显示文摘 | TAGHAV1 F SAGHAFIAN H KHARRAZ1 Y H K | 2009 | Materials Design2009，30，5： | 1 |
| 16 | Effect of water and cement ratio on compressive slrength amt abrasion of microsilica con cte 显示文摘 | RAtlMANI K SIIAMSAI A SAGHAFIAN B el al | 2012 | Middle-Eas! Journal of Scientific Research2012，12，8： | 1 |
| 17 | A numerical study on slip flow heat transfer in micro-poiseullle flow using perturbation method 显示文摘 | Saghafian M Saberian I Rajabi R Shirani E | 2015 | Journal of Applied Fluid Mechanics2015，8，1： | 1 |
| 18 | Study on vibration for the production of thixotropic microstructure in A356 aluminum alloy显示文摘 | F Taghavi H Saghafian the ability of mechanical Y H K Kharrazi | 2009 | Materials and Design2009，30，： | 1 |
| 19 | Study on the Effect of Prolonged Mechanical Vibration on the Grain Refinement and Density of A356 Alumi num Alloy显示文摘 | Taghavi F Saghafian H S Kharrazi Y H K | 2009 | Materials and Design2009，30，5： | 1 |
| 20 | Runoff hydrograph simulation based on time variable isochrone technique显示文摘 | SAGHAFIAN B JULIEN P Y | 2002 | Journal of Hydrology2002，261，： | 1 |
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