Reza Bakhtiari

   This research investigates the transient liquid phase bonding process assisted by electric current for joining thin sections. The simulation of this process was conducted using COMSOL software in two systems: copper-carbon steel-copper and copper-tin-copper, with varying layer thicknesses. The primary objective was to analyze temperature distribution and atomic diffusion during the bonding process. The results showed that in the copper-carbon steel-copper system, the temperature at the center of the piece reached approximately 1590°C, sufficient to melt the interlayer. It was also observed that increasing the base layer thickness from 1 mm to 5 mm resulted in a higher final bonding temperature. Atomic diffusion analysis revealed that the maximum diffusion depth occurred with a base layer thickness of 1 mm and an interlayer thickness of 0.02 mm, reaching a depth of 0.252 mm. In the copper-tin-copper system, the center temperature of the sample reached approximately 766°C, adequate for melting the tin layer. Modeling indicated that in both systems, the sample remained at the final bonding temperature for over 95% of the bonding time, highlighting a unique advantage of this method. The results were validated by comparing them with experimental data available in the literature, showing good agreement. This research's findings can contribute to the optimal design of transient liquid phase resistance bonding processes for industrial applications, particularly in microelectronics.

Developing the scope of application of new material depends on understanding the behavior of these in different environments and also gaining knowledge on the effect of various factors such as heat treatment parameters on their properties.   With regard to this issue we focused on the investigation the effect of partial austenitizing duration on creating a matrix with a dual structure of ferrite-ausferrite, corrosion resistance, bending strength, time to failure in crosive media under applied bending loads and stress corrosion threshold stress of a carbidic austempered ductile iron (CADI) which has been known as new family of ADI. In this regard, cast parts from a non-alloy carbidc cast iron were first subjected to ferritizing annealing to obtain full ferritic matrix. Then, the samples were partially austenitized at 870 ?C for 10, 15, and 20 minutes, followed by austempering in a molten salt bath at 350 ?C for one hour. After it, samples microstructures were examined with an optical microscope. In the next step, electrochemical corrosion tests were performed with Tafel polarization method. Then, by preparing notched and smooth C-ring samples, the loads leading to their failure were determined under the bending tests in air. Finally, the behavior of C-ring samples in corrosive caustic soda solution were investigated under bending loads. According to the obtained results, with the increase of the partial austenitizing time, the ausferrite phase fraction increased according to the JMAK equation. The creation of dual matrix structure of ferrite-ausferrite caused the corrosion resistance of the samples to be weakened compared to the samples with fully ferritic matrix and conventional ADI. As the partial austenitizing time increased, the corrosion resistance, bending tensile strength in air and time to failure in corrosive media under constant load, increased. The bending loads leading to the failure of notched samples in air were significantly lower than those of smooth samples. The results of stress analysis in C-ring samples under bending test in air showed that the reduction of cross-sectional area, change the outer effective radius and neutral radius of the samples, and stress concentration are three contributing factors in reducing the tolerable bending load without occouranse failure with the contribution of 35%, 35% and 30%, respectively. The notch strength ratio (NSR) was independent of the effect of partial austenitizing time and it was about 0.87. All the smooth samples endured 100 hours of stress-corrosion testing under maximum applied loads (equivalent to 85% of failure load in air) without occurrence of failure. By decreasing the applied load in the corrosive environment, the time to failure of all samples increased greatly. There was a power relationship between the stress-corrosion threshold stress and the ultimate tensile strength of the samples. Also, during stress-corrosion testing the gradual fracture along with growth of cracks was not observed and failure of all samples in both environments air and caustic soda occurred via very rapid crack propagation in a completely brittle mode over the whole range of the applied loads.   

   In the process of additive manufacturing of metals, the ability to predict and control the microstructure can reduce the need for subsequent heat treatment. In this research, the numerical simulation of the additive manufacturing process of 316L stainless steel was studied. The ability to predict and control the microstructure of materials in selective laser melting (SLM) requires understanding the thermal conditions during the solidification process. In this research, process parameters were selected with transient thermal characteristics, i.e. temperature and cooling rate. The relationship between the cooling rate and the temperature gradient during local freezing, and the control parameters of the laser selective melting process were investigated, which were the control parameters of the laser scanning speed and the thickness of the powder layer. Also, solidification parameters, namely thermal gradient (G) and solidification rate (R) were investigated to predict the microstructure. In this project, the cooling rate and thermal gradient during solidification were calculated numerically by solving the relevant heat transfer equation using the finite element method in Comsol software, and then the results included the solidification parameters mentioned on the solidification map of 316L stainless steel alloy to predict the solidification microstructure. was imaged The results of this research (obtained using simulation) showed that the microstructure of 316L stainless steel produced by the selective laser melting (SLM) process will be columnar or cellular dendrites. Also, it was found that high laser scanning speed (i.e. speed of 1000 mm/s) leads to finer microstructure. Furthermore, the values of G × R increase from the bottom to the top of the melt pool geometry, leading to a finer structure in the top region. But the values of G/R decrease from the bottom to the top of the molten pool geometry. Also, in this research, it was found that the greater the thickness of the powder in each layer, the lower scanning speed should be used so that the laser heat flux can melt the powder and the sub-layer completely. By increasing the laser scanning speed from 200 to 1000 mm/s, the width decreases from 85 microns to 58 microns and the depth of the molten pool decreases from 23 to 13 microns, but the length of the pool increases from 93 to 97 microns.

      In recent years and with the increase in the number of elderly people in different countries, the supply and demand for the use of titanium and its alloys in the manufacture of implants used in the human body such as hip joint prosthesis, joint replacement, knee replacement, fracture fixation and dental implants have increased.   has increased widely.   In medical applications, in addition to the usual properties of alloys, other factors such as topography and surface energy are also considered, which play an important role in the adhesion of bone cells to the implanted surface.   As a result, the surface of the material plays an important role in the body's response to the implantable material.   The purpose of this research is to investigate the effect of some variables of the sandblasting process, acid washing and heat treatment on the surface characteristics and cellular response of titanium.   In order to modify the surface of the titanium substrate, first the samples were sandblasted using alumina powder, then they were etched in a solution containing nitric acid and sulfuric acid for the necessary time.   After that, the samples were placed in the oven at temperatures of 300, 400, and 500 degrees Celsius for one hour. A group of samples were left without heat treatment.   In order to measure roughness, hydrophilicity, investigate surface morphology, investigate phase compounds, cytotoxicity and biocompatibility of substrates, various tests and equipment including roughness meter, water contact angle measurement system, XRD, cytotoxicity and SEM were used to investigate cellular morphology.   The results of the X-ray diffraction test showed that the dominant phase formed is the Ti6O phase.   Of course, a small amount of Ti2O3 was also formed.   The above groups cause better calcium deposition through reaction with body fluids.   And the results of the hydrophilicity test showed that the amount of wetting angle ?m decreased with increasing sandblast pressure and especially with heat treatment compared to the control samples.   However, in most of the samples, by increasing the temperature of heat treatment to 500 degrees Celsius, the contact angle has increased and the wettability has decreased.   Regarding the evaluation of cell viability, the produced levels did not show any signs of cytotoxicity.   In fact, the roughness of the surfaces obtained after sandblasting and acid etching were able to strengthen the attachment and proliferation of MG-63 cells on their surfaces.

Aluminum 3819 due to its good corrosion resistance and high strength-to-weight ratio in marine, military, pipe- It is widely used in pressure vessels, shipbuilding, refrigeration industries, oil rigs and gas transmission lines. among All aluminum alloys, alloy 3819 for all welded assemblies, tanks with the highest welding efficiency and maximum strength, connection of marine equipment, bridges, cargo ships, heavy ships and marine organizations, TV masts, grinding equipment, recycling machine body transfer equipment and wherever needed Corrosion resistance equipment is widely used. A Ag/Sn/Ag system to Shar et al connected with ultrasonic assistance and concluded that the acceleration of Ag atomic penetration with ultrasonic assistance is 6 3 times faster - - than the traditional TLP connection. Gio et al. fine-grained 4897 aluminum alloys with zinc interlayer TLP method with the help of ultrasonic bonding and reported that long ultrasonic time increases Zinc penetrates into aluminum. Li et al. for bonding Ag/Mg using ultrasonic assisted TLP method used and obtained the optimum shear strength of 68 MPa in a short period of 7 seconds. At This research has examined the TLP connection with the help of ultrasonics. This type of connection can not only connect with It provides high mechanical properties but also acts as a low temperature joining method. TLP with help Ultrasonic does not need shielding gas and can accommodate complex structures. Until today TLP It is used to connect different materials with the help of ultrasonic.  

   Abstract:    Ti-6Al-4V alloy with good tribological properties, low elastic modulus, high strength to weight ratio and Co-Cr-Mo alloy with excellent corrosion and abrasion resistance are used as metal biomaterials in artificial joints. In this study, the biocompatibility of the bimetallic system of Co-Cr-Mo and Ti-6Al-4V alloys, which are connected to each other through the transient liquid phase (TLP) process was evaluated. In this study, samples without coating and with hydroxyapatite coating were evaluated. The Phase composition, coating microstructure, corrosion resistance, metal ion release rate and cytotoxicity of samples were examined by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Polarization, Inductively Coupled Plasma (ICP) and MTT tests. The results showed the presence of uniform and nanometer coating on the coated samples. Examination of corrosion resistance in SBF solution and blood serum showed that CT1 sample without coating had optimal resistance (icorr = 1.01 ?Acm?2 in serum solution and icorr = 1.25 ?Acm?2 in body simulation solution) and also the resistance of coated samples It is much more desirable than uncoated samples and the best result was related to HAp-CT1 sample (icorr = 0.1 ?Acm?2 in serum solution and icorr = 0.08 ?Acm?2 in body simulation solution). The results of ICP test showed that the release rate of ions in 7, 14, 28 days was less than the allowable limit. By performing cytotoxicity test, it was observed that the death rate of cultured cells on the samples within 3 days was a desirable value and close to the control sample and had a significant difference of p <0.05. In addition, cell growth on CT1 sample increased during 3 days, which indicates the optimal biocompatibility of CT1 sample compared to other samples. The results of tests performed in this study showed that the samples have good biocompatibility and the best result is related to CT1 sample. It was also observed that the hydroxyapatite coating applied on the samples significantly increased the biocompatibility rate. Key Words: TLP bonding, Biocompatibility, Corrosion Resistance, Metal Ion Release, Cytotoxicity.

  gt; In this study, pure chitosan membranes and its matrix mixed with nanoparticles of graphene oxide quantum dots (fabricated in this study) crosslinked with glutaraldehyde were used to dehydrate ethanol. High hydrophilicity of chitosan resulted in acceptable dehydration function of chitosan membrane in ethanol dehydration process. Also, due to the hydrophilic functional groups and good dispersion of graphene oxide quantum dots in the chitosan network, the mixed matrix membranes performed better dehydration than the chitosan membrane. Matrix membrane mixed in optimal loading of quantum dots graphene oxide (1.5 wt%) flux0.811 kg/m2h and separation factor of 801 for dehydration of water / ethanol mixture (90/10) at 40°C Showed that compared to chitosan membrane, the flux base increased by 84% and the separation coefficient increased 7.6 times

One of the most important issues in welded parts is the existence of residual stress due to the heat distribution. In this research the effect of residual stress on the energy absorption of steel tubes due to spiral welding, using various parameters such as the number of spirals and welding current intensity, in the manner of experimental/simulation has been studied. The compressive test has been used in order to determine the amount of energy absorption in the welded tubes. Also in the numerical simulation, the spiral welding process, heat distribution, residual stress distribution, tube folding and the force-displacement diagrams has been investigated. At the end, the results of experimental tests and numerical simulation has been compared and analyzed.   

    Erosion-corrosion is a main type of damage mechanisms taking place in equipment and hydraulic components exposed to corrosive flowing fluid. Hence, in order to applications of dual phase steels for such engineering components, it is essential to have a comprehensive understanding of their erosion-corrosion behavior and involved affecting variables. The microstructure of dual phase steels is governed by the heat treatment variables like temperature of medium in which the samples are rapidly quenched from intercritical austenitizing temperature. As a results, the change in quenching medium temperature is expected to have a significant impacts on the erosion-corrosion resistance of dual phase steels. The purpose of this work was to provide comprehensive information on this issue and to evaluate erosion-corrosion correlation with the hardness and erosion resistance of dual phase steels. In this regard, several sets of samples of Ck45 steel were austenitized at 730 oC for 60 min, then quenched and held 120 min in water and/or salt bath with different temperatures ranging of 25 to 400 oC to obtain dual structures with ~40 vol. % fraction ferrite. Optical microscopy and scanning electron microscopy utilized to characterize the samples microstructures. The hardness of specimens were evaluated using Brinell hardness test method. Erosion and erosion-corrosion tests were carried out by immersion of samples in a solution of distilled water, 3.5 wt% NaCl and 1 wt% Al2O3 and rotating them with 715 rpm (9 m/s) for durations of 24-120 h. The slope of variation of mass loss various duration test was determined as erosion or erosion-corrosion rate. The obtained results revealed that increasing the quenching medium temperature from 25 to 400 ?C leads to a reduction in hardness and erosion resistance. The erosion rate was correlated with quenching medium temperature as a power model with exponents of 5.7. The rate of erosion-corrosion was raised with increasing quenching medium temperature from 25 to 325?C, while austempering at higher temperature resulted to improvement of erosion-corrosion resistance when compared to specimen austempered at 325 oC.   The power model was valid for correlation between the erosion rate and Brinell hardness, while there was no significant correlation between erosion-corrosion rate with hardness and rate of pure mechanical erosion. Compared with pure mechanical erosion in non-corrosive fluid, the degradation rates were higher than 193% to 305% and 21% to 132% for samples austempered at temperatures below and above 325 oC, respectively, when the erosion tests were performed in the aggressive condition. The erosion-corrosion resistance of ferrite-bainite samples prepared by austempering at temperature of 400 oC was similar to ferrite-martensite sample provided by quenching into water at temperature of 90 oC and had the best results compared to the rest of the specimens, except for quenched samples in water at 25 ° C.   While the pure mechanical erosion resistance of later was approximately  three time  greater  tha  that of former. These results indicate that the type of hard phase in the dual phase steel does not have much effect on its efficiency in the corrosive flowing fluid, if the appropriate temperature was selected for the quenching medium. But, ferritic-martensitic dual-phase steel is preferred for use in the non-corrosive environment and/or when the samples are subjected to cathode protection.

  In this research, the AISI304 steel was bonded successfully with MBF-15 and MBF-80 interlayers by Transient Liquid Phase [1]method. Then friction stir process[2] was performed on the bond region and the effect of the process on microstructure and mechanical properties was investigated. The base metal and each of interlayers separately was assembled and the bonding operation was done in 11350c temperature for 20 min in a semi-vacuum environment furnace. Afterward Friction Stir process applied with using a designed tool made from tungsten carbide material. The process was accomplished with a milling machine. Rotating speed of tool was 600 Rpm/min and traverse speed was 10 mm/s. the process was applied at two side of the bond line. Processed and not processed samples were prepared and investigate with optical and scanning electron microscope. The microstructure of samples compared with each other. To analyze the composition and phase recognition energy dispersive spectrometry[3] and XRD was used. To evaluate the mechanical properties and the effect of FSP on it shear strength test and micro hardness performed. The microstructure evaluation showed that before FSP for each of interlayers, there were some eutectic phase in center of bond and residual phase in the diffusion zone of TLP. Before FSP, for MBF-15 interlayer, the central phase is Ni-Si, Fe-B, Ni-B and CrB4 in DAZ of TLP. The eutectic phases in the central zone of bond by MBF-80 interlayer are Fe-B-Ni-B and brittle Cr5B3 in DAZ. These eutectic and residual phases reduce the mechanical strength of the joint.FSP was applied as a technique to modify the distribution of alloying elements and intermetallic phases. Underneath of FSP route, 3 zones were formed: 1. Nugget zone that distribution of intermetallic is perfect. 2.Thermo Mechanically Affected Zone[4]. and. 3. Heat Affected Zone [5]that the quantity of intermetallic phases is reduced because of dissolution of eutectic and residual phase. The shear strength and hardness of the nugget zone after FSP will be better than before FSP for both interlayers. This improvement for joint with MBF-15 interlayer is better than MBF-80.   And shear strength of joint with MBF-15 interlayer is close to base metal shear strength after the process.1-TLP2-FSP3-EDS

شبيه سازي رشد ترك در چدن نشكن آستمپر شده تحت سايش خستگي

  The natural gas contains many impurities, including water, carbon dioxide ( ), and so on. The presence of acid gases in natural gas will lead to a reduction in thermal value, which is why removing these gases from natural gas to a standard value will be important. Increasing permeability and selectivity are the most important goals of research in membrane field. One of the common ways to achieve these goals is to add inorganic particles to the polymeric matrix of membranes, which are called as mixed matrix membranes.In this work, we present simulation of the effective permeability of pure gas in mixed-matrix membranes (MMMs) by CFD. For this, we use the finite element method to simulate gas effective permeability based on constructing three-dimensional MMM models for solving Fick's diffusion equation to obtain the concentration profiles.Our simulation also indicate effects of various structural parameters, including the filler volume fraction, interface solubility ratio, and diffusivity ratio and filler size. And also result of simulation for   effective permeability of MCM-41 fillers compared by effective medium theory (Maxwell model).Our approach shows improved predictions compared with the Maxwell model.    Key words: Mixed Matrix Membrane, Gas separation, Simulation, Finite-element, Comsol

  this present literature investigates the thermal buckling and vibration of functionally graded porous nanocomposite beam reinforced by graphene platelets based on Timoshenko beam theory . This study focuses on the effect of the porosity distribution , porosity   coefficient and the effect of the variou   GPLs dispersion pattern , size and geometry of GPLs ,as well as the influence of   eam boundary conditions ,slenderness ratio and the thermal gradient   . Because of the negative thermal expansion coefficent of graphene , the critical thermal buckling gradient is in a high range. the numerical results suggest that introducing the little amount of GPLs enhances remarkably the stiffness of the present structure ,on the   other hand ,due to negative thermal expansion coefficient of nano fillers ,the studied beam acceptably behaves in high thermal gradient .Both porosity distribution and GPLs pattern obviously affect on frequency increment   although the effect of GPLs pattern is more .In a certain ,when the porosity coefficient increases ,the frequency increment decreases , though this decrease is much less . the effect of   oundary conditions on frequency increment is not so much. According to the results ,the relation between slenderness ratio and frequency is inverse.  Analyzing the effect of   increase on beam frequency suggests that increasing thermal gradient , the beam frequency lessens. Meantime The effect of   increase on frequency increment is different in beams with various porosity distributions and GPLs pattern.

synthesis and Characterization of core-shell nanoparticles(YSZ@Ni nanoparticles)

<  gt;پيش بيني وقوع عيوب مركزي در فرآيند اكستروژن ميله</P>

Design Of Ultra Wideband Low Noise Amplifier (LNA) With Current Reuse And Noise Cancelling Technique

  The Ti-6Al-4V alloy with good tribiological characteristics, low elastic modulus, high strength to weight ratio and the Co-Cr-Mo with excellent resistance to corrosion and erosion, are practical as metal bio-materials in artificial joints. The Co-Cr-Mo alloy leads to reduced corrosion in the thigh joint and the Ti-6Al-4V alloy easily pairs up with surrounding bones and is therefore preferred for thigh stem. To build such a bimetal system, given the disparity of welding parameters, connection is a big hurdle. Different welding methods such as fusion welding, laser welding, hard and soft soldering, and penetration bonding for simillar and disimillar bonding of these alloys have been used. In this study, the transient liquid phase   rocess has been used for the Ti-6Al-4V/Co-Cr-Mo dissimilar system in order to address the shortcomings of other welding methods and access mechanical properties comparable with base metal. In this method, samples were cut as cylinders with 8 mm in diameter and 5.7 mm in height and their surfaces were prepared for bonding. An copper interlayer was placed between the two surfaces as covering on cobalt sample, and a constant pressure of 1 MPa was applied to the samples using fixture. Next, the bonding set was exposed to heating in under-pressure stove with the different temperatures of 925, 950 and 975, considering the eutectic temperature of Ti-Cu (about 875 °C), for 5 to 120 minutes. On the connected samples, cross section cut was performed and the substructure was studied using optical microscope. Results suggested that as a result of the bonding, 3 zones of DAZ (diffusion-affected region), ASZ (athermally solidified zone), and ISZ (isothermally solidified zone) appear in the bonding point, with the length of these zones differing depending on conditions of performing the bonding, and as joint temperature and duration increases, the athermally solidified zone can be removed, thus leading to progressed isothermally solidification during the bonding. Cut test was used to investigate mechanical strength of the samples, with the maximum shear strength equal to 350 MPa, which is around 50% of the base metal, obtained for the bonding made at 950 °C and in duration of 2 hours. Also, the failure level of the samples was identified with the X-ray diffraction test and failure level combination was considered. Type of failure and elements present in different phases of sample cross-sections were investigated using scanning electron microscopy. Elements constituting present elements were identified via the EDS test, and element changes in the sample were obtained with linear analysis. Keywords: transient liquid phase (TLP), Ti-6Al-4V, Co-Cr-Mo, evaluation of microstructure, mechanical properties, copper interlayer  

  In this research, utilizing transient liquid phase (TLP) joining for bio as-cast Co-28Cr-6Mo alloy similar bonding was investigated. Due to the good abrasion resistance, high mechanical properties, adequate corrosion resistance, high biocompatibility, as well as lower prices than gold base alloys, these alloys are the most suitable for biomedical applications. To this end, the TLP connection was performed using a MBF-100 cobalt-based and MBM-60 nickel-based interfacial layer with a thickness of 25 microns under argon gas atmosphere conditions at 1175 ?C and 15 min, and 1160?C and 60 min, 1170?C and 30 minutes , 1170 ?C and 60 min, and 1170 ?C and 120 min. The MBF-60 nickel base MBF-60 interface was also subjected to ambient atmospheres and vacuum of   torr at 950, 1000, 1050, 1100, 1170 and 1240 ?C.In order to test the mechanical properties of bonding, the bonded specimens were subjected to cutting tests. The results showed that the bond strength of MBF-100 interlayer at 1170 ° C and 2 h had the highest shear strength. The strength of sample bonding was reached 81% of base metal. Also, the effect of complete thermal solvent treatment at 1240 ° C and 4 h on shear bond strength was investigated. It was observed that at the same temperature and time, the complete solution sample had a higher strength than the bonding of as-cast samples in similar conditions. The highest bond strength was   for MBF-60 at 1000 ° C and 2 h.Investigation of microstructural analysis of the bonding was done using optical microscope and scanning electron microscopy (SEM) and SEM-EDS analysis results. The results of the bonding samples of 1175?C and 15 min using MBF-100 interlayer indicated that the melting was done on the boundaries at a bonding. By increasing the bonding time to 2 h at 1170?C, the penetration rate expanded, resulting in uniformity of the bonding region compounds and reduction of the phases present in the bonding region, indicating the expansion of the isothermal solidification zone. Boride compounds were also found in this sample indicate their stability.In joining studies conducted with the MBF-60 interlayer, it was found that in the bonding sample at 1000 ° C and 2 h, according to the EDS analysis the compounds were isolated as Cr3P3, Crp, Cr12P7, and CoP, and the phases Spherical is also seen in the DAZ zone. At temperatures, 1170° C was also observed continuous eutectic compounds at the center of the joint. The standard homogenization carbides dissolution process was carried out at 1240 ° C for 4 h the temperature for 4 hours. According to the microstructure bonding, the undesired phases of the bonding zone were significantly reduced and the homogeneity was observed. At this temperature, the carbides were completely dissolved and the granularity formed in the bonding zone.  

<  gt;توليد كامپوزيت زمينه آلومينيومي تقويت شده با شبكه سيمي فولادي</P>

Abstract:  The pipelines that are used in the petroleum industry tra  ort gas and oil with content of sulfidric gas that intensifies the adsorption of hydrogen in the metallic surface provoking the absorption of hydrogen in the wall of the pipe, what can flow in a embrittlement processThe welding process and the manufacturing process can also facilitate entry of hydrogen into the steel.The work done by other researchers suggest several parameters in the hydrogen losses had an impact. For example, have shown that the microstructures ferritic microstructure of ferrite needle more resistant to damage by hydrogen. Also tempered martensite microstructure bainite structures to very fine particles, perlite and martensite shows better behavior. Impurities and inclusions as trapping hydrogen in steels resources to act. Manganese sulfide is known as a harmful impurities.In this project, API 5L X60 pipes used in oil refineries Ntg Bijar area Kermanshah related to oil and gas companies have been defeated West under analysis. It was found that impurities MnS significant role in the formation of cracks were HIC. So that all EDS analysis show the presence of these impurities left in the region. Studies also show that the microstructure of the steel microstructure ferrite - pearlite with a hardness of 210 Vickers is that in some parts of needle ferrite and ferrite Weidman Ashtatn was observed in some areas.

Analytical modeling of functionally graded carbon nanotube reinforced composite plates under low velocity impact