JOURNAL OF NEW MATERIALS
Year:2011 | Volume:1 | Issue:2|Papers Count:8

Polarization curves, is an important tool in determining the parameters of corrosion, especially corrosion current density. The parameters determined by the procedures done in their assumptions simple drop-in is to be considered and at some systems, a lot of error is generated. In this study a new mathematical method, based on a model that Rocchini has suggested, to measure the polarization resistance and corrosion current density, using the experimental data is presented. Method used because of the extended power Mac Lauren function of i (DE) uses and can be used for all experimental systems, without any limitations. This approach is not based on mathematical analysis of the sequence being convergent because of problems in some systems, and solutions cannot be wrong. According to this method, a software (Electrochemical Kinetics Modeling Software) EKMS in the Matlab programming environment was designed. The comparison between experimental data from various sources and data from software shows good agreement.

In this study, microstructural transformations in AISI 201 L stainless steel during advanced thermomechanical process is investigated. The as-cast specimens were first homogenized at 1200oC for 15 h, and then hot forged in order to prepare a suitable microstructure for the subsequent treatment involving conventional cold rolling and annealing. Cold rolling was carried out at reductions of % 10-95. The reversion of martensite to austenite in the cold rolled specimens was carried out by annealing in the temperature range of 750-900oC for different times from 15 to 1800 s. The specimen microstructures were observed by optical and scanning electron microscopy (SEM). The identification of different phases was carried out using X-ray diffraction (XRD) and Feritscope. The results showed that increasing the strain resulted in an increased volume fraction of the strain induced martensite during cold rolling and a reduced martensite saturating strain. Also, the nanocrystalline austenitic structure with an average grain size of about 100 nm was obtained by annealing the %95 cold rolled specimen at 850 and 900oC for 30 s.

In This study proportion of low cement alumina-silicon carbide refractory castables are considened to produce iron melt runners in iron and steel industry. Different size of silicon carbide from 16 to 1200 mesh are used. Measurements of cold crushing strength (CCS) and bulk density(B.D) showed that 46 mesh produces the best physical and mechanical propertion. Highes silicon carbide content inceares the resistance to melt and slag. On the other hand production of CO and CO2 gases is increased. The effect of the amount of SiC on castable properties (CCS and B.D) was considened and together with XRD studies indicated that 15% SiC is the optimum.

In this work the plane-strain rolling problem was solved by the Elastic -plastic, finite-element method with elastic-linear work hardening effect. This simulation is taken with ANSYS software. For approving the model, the result was compared with experimental results, found in the literature. The effects of variation of friction coeficient are investigated on roll pressure, shear stress and roll force distributions.

In this investigation, feasibility of applying severe plastic deformation (SPD) on pure magnesium and AZ91 alloy is considered at room temperature. This task was performed by application of simple shear extrusion (SSE), a new severe plastic deformation technique which is capable of applying high strain values in a gradual manner. Results obtained by this method were compared with those of other conventional SPD techniques, namely equal channel angular pressing, channel angular deformation and dual equal channel lateral extrusion. Investigations on macroscopic shape of the samples and their microstructure evolution show that SSE is a promising SPD technique for processing of magnesium alloys at lower temperatures.

In this research, Hot deformation behavior of two casted duplex stainless steels with different percent Cr, Ni and Mo was studied and then the initial microstructural effect in terms of ferrite to austenite volume fraction on hot deformation behavior was studied. The specimens were subjected to hot compression tests at temperatures of 900- 1100oc and strain rates 0.001 s-1 and 0.1 s-1 The results showed that the flow stress-level of the samples are strongly in relation with deformation parameters and initial microstructures of steels. The strain rate sensitivity (m) was determined and found that changed from 0.27 to 0.23 for C1 and changed from 0.22 to 0.09 for C2 while temperature rise from 900oC to 1100oC. The apparent activation energy Q was calculated as 316 and 355 kl/mol for C1 and calculated as 780 and 390 kJ/mol for C2 in low and high temperatures, respectively.

According to previous research, numerous and diverse mechanisms associated with graphite phase formation in cast irons and especially spherical graphite is presented. In this study after casting ductile cast iron in the form of a staircase, the influence of different thickness on size, shape, distribution and especially the internal structure of graphite by using optical microscope, scanning tunneling microscope (STM) and scanning electron microscope (SEM) has been investigated. The results show that by changing the cross section and they cooling rate serious changes in all of these parameters is introduced.

The effects of Li on the microstructure and mechanical properties of Type A380 aluminum casting alloys have been examined. It is shown that, as the Li content is increased up to 0.1 wt.pct in the base alloy (Al-8.5 wt.%Si-3.5 wt. %Cu-1 wt.%Fe), Li successfully modifies the morphology of the b-Al5FeSi and eutectic Si phases from coarse intersected and branched platelets into finer and fibrous ones. The 0.06%wt Li-containing alloy exhibits higher strength and elongation, presumably due to both finer b-Al5FeSi and eutectic Si phases. In amounts greater than 0.06%wt lithium, Reduction of the strength and elongation can be due to increasing porosity and creation of other undesirable phases.