A. Kermanpur
Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran
[ 1 ] - 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 enhnac...
[ 2 ] - The Effects of Nitrogen Addition on the Production of Ultrafine/Nano Grained AISI 201L Stainless Steel by Advanced Thermo-mechanical Process
In this study, the effects of nitrogen addition on the production of ultrafine/nano grained AISI 201L stainless steel by advanced thermo-mechanical process were investigated. Cast samples were first homogenized at 1200 °C for 4 h, hot-rolled at 1100 °C and finally, solution-annealed at 1150 °C for 2.5 h. Unidirectional and cross multipass cold rolling at 25 °C was carried out to 90% reduction i...
[ 3 ] - The Effect of Niobium on the Formation of Nanostructured Low Carbon Steel Using Martensite Treatment
The formation of nano/ultrafine grained ferrite in low carbon steels containing different amounts of niobium was investigated using thermomechanical treatment which consisted of annealing of 85% cold rolled martensite with different parameters. The specimens were characterized by optical and scanning electron microscopy and Vickers hardness test. A lamellar dislocation cell structure was formed...
[ 4 ] - The Effects of Martensite Thermomechanical Parameters on the Formation of Nano/Ultrafine Grained Structure in 201LN Stainless Steel
In this study, the effects cold rolling and annealing parameters during thermomechanical processing of the AISI 201LN stainless steel were investigated. The cast samples were homogenized, hot-rolled and solution-annealed to acquire a suitable microstructure for the subsequent thermomechanical treatment. Unidirectional and transverse multi-pass cold rolling at 25, 0 and -15 °C was carried out to...
[ 5 ] - Effect of annealing process on microstructure and mechanical properties of high manganese austenitic TWIP steel
In the present study, the influence of annealing temperature on mechanical properties and the microstructure of a high manganese austenitic steel (Fe-30Mn-4Al-4Si-0.5C) was investigated. X-ray diffractometry, optical and scanning electron microscopy, hardness and tensile tests were used to analyze the relationship between mechanical properties and microstructure after annealing process. The res...
[ 6 ] - Artificial neural network models for production of nano-grained structure in AISI 304L stainless steel by predicting thermo-mechanical parameters
An artificial neural network (ANN) model is developed for the analysis, simulation, and prediction of the austenite reversion in the thermo-mechanical treatment of 304L austenitic stainless steel. The results of the ANN model are in good agreement with the experimental data. The model is used to predict an appropriate annealing condition for austenite reversion through the martensite to austeni...
[ 7 ] - Color metallography; a suitable method for characterization of martensite and bainite in multiphase steels
Color metallography is a useful method for characterizing microstructures of steels with multiple phases. In this paper, application of three different color etching techniques for a bainitic-martensitic steel is reported. Comparisons between the results showed that 10% Na2S2O5 aqueous solution was the best etchant for distinguishing martensite, bainite and ferr...
[ 8 ] - Effects of Homogenization Conditions and Hot Rolling Parameters on Grain Refinement of an As-Cast 301 Stainless Steel
In this work, effects of homogenization time of 3 to 13 h at 1200 °C on the grain refinement of as-cast AISI 301 stainless steel after different hot rolling conditions were investigated. The results showed that the minimum grain size of 16±7 mm was achieved when homogenization took place at 1200 °C for 9 h followed by hot rolling at temperature range of 1000–1200 °C with strain of 0.8 and stra...
[ 9 ] - Factors Affecting Weldability Improvement of Dissimilar Welds of Aged HP Stainless Steel and Alloy 800
The microstructure of HP stainless steel in aged and aged + solution annealed conditions and solutionized alloy 800 was characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) equipped by EDS. All phases present in the above condition were described. The effects of solution annealing heat treatment temperature on the microstructure, te...
[ 10 ] - Three-dimensional Numerical Simulation of Metal Flow and Solidification in the Multi-cavity Casting Moulds of Automotive Components
The liquid metal flow and the solidification behaviours in a multi-cavity casting mould of two automotive cast parts were simulated in three dimensions. The commercial code, FLOW-3D® was used because it can track the front of the molten metal by a Volume of Fluid (VOF) method and allows complicated parts to be modeled by the Fractional Area/Volume Obstacle Representation (FAVOR) meth...
[ 11 ] - شبیهسازی عددی گرمایی- ساختاری فرایند کوئنچ فولادها
In this work, a 3D thermo-microstructural model was developed to simulate the continuous cooling of steel. The model was employed for simulation of cooling process of the gears made from a plain carbon steel (AISI 1045) and a low alloy steel (AISI 4140). Temperature-dependent heat transfer coefficients for two different quenching media were evaluated by experimental and computational methods. ...
[ 12 ] - ON THE FORMATION OF STRAY GRAINS IN DIRECTIONALLY-SOLIDIFIED NI-BASED SUPERALLOYS WITH VARYING CROSS SECTIONS
Formation of stray grain defects particularly around re-entrant features of the turbine blade airfoils is one of the major problems in directional and single crystal solidification processes. In this work, directional solidification tests of the GTD-111 Ni-based superalloy were conducted at different withdrawal velocities of 3, 6 and 9 mm.min-1 using various stepped cylindrical and cubic design...
[ 13 ] - Prediction of Mechanical Properties of TWIP Steels using Artificial Neural Network Modeling
In recent years, great attention has been paid to the development of high manganese austenitic TWIP steels exhibiting high tensile strength and exceptional total elongation. Due to low stacking fault energy (SFE), cross slip becomes more difficult in these steels and mechanical twinning is then the favored deformation mode besides dislocation gliding. Chemical composition along with processing ...
[ 14 ] - Effect of Mold Preheating on the Microstructure of the Investment Cast Astm F-75 Implant Alloy
The ASTM F-75 (Co-28%Cr-6%Mo) is widely used as a biocompatible alloy in medicinefor manufacturing implants. In this study, effect of mold preheating on the as-cast microstructure of thealloy was investigated using the solid investment casting process. Several mold preheating temperaturesof 550, 700, 850 and 1000 °C were selected at the same melt superheat. The samples were characterizedby opti...
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