Abstract: Recently a ferrous-based Fe-28Ni-17Co-11.5Al-2.5Ta-0.05B (at.%) shape memory alloy (abbreviated NCATB) has attracted attention because of its huge superelasticity (～13%). In order to manufacture this alloy on a large scale, a deeper knowledge of the plastic deformation behaviour of the alloy is required. During hot deformation, temperature and strain rate exert significant effect on the mechanical properties. The main objective of the work, therefore, is to investigate the influence of deformation parameters, such as temperature, strain rate and strain, on flow behaviour of an NCATB shape memory alloy. Flow behaviour tests on an NCATB alloy were performed on a Gleeble-3800 thermomechanical simulator at deformation temperatures of 1100, 1150 and 1200°C and strain rates of 0.1, 1.0 and 10s-1 with the strains maintained at 0.2, 0.4 and 0.6, respectively. The workpiece is considered asa dissipater of power, and the features of power dissipation will,therfore, be seen as changes in the microstructure. These features of power dissipation are measured by a parameter called efficiency of power dissipation (η). It is directly related to the strain rate sensitivity parameter(m). Taguchi method is used to evaluate the influence of deformation temperature, strain rate and strain on efficiency of power dissipation. Based on the results, optimum parameters for higher efficiency of power dissipation are: 1150°C (temperature), 0.1 s-1 (strain rate) and 0.2 (strain). An analysis of experimental results in terms of percentage contribution reveals that strain rate plays a more predominant role (39.73%) compared to temperature (24.03%) and strain (32.73%) on NCATB alloy.
Abstract: This study investigates how the use of Inconel filler metal 625 affects the microstructure and mechanical properties of gas tungsten arc welded joints of an IN-713LC nickel-based superalloy. Due to their difference in composition, obvious weld beads could be found by X-ray detection. In addition, it was found that the γ' strengthening phase was absent and carbide was present between the matrix and the weld bead during gas tungsten arc welding. These carbides are strongly related to the formation of cracking and weld shrinkage during solidification. The absence of the γ' strengthening phase and the presence of weld shrinkage and cracking led to a decrease in the hardness, tensile strength, and elongation of the welded pieces.
Abstract: In this paper, the hot compression tests were performed to study on deformation-induced pearlite transformation in vanadium microalloyed eutectoid steel. The results showed that volume fraction of deformation -induced pearlite were higher and the pearlite were spheroidized better under lower strain rate and higher strain in vanadium microalloyed steel. Ferrite grains and granular cementites were further refined through vanadium microalloying combined with deformation-induced pearlite transformation .Vanadium dissolved in γmatrix could retard deformation-induced pearlite transformation under low strain, vanadium carbides precipitated due to strain-induced precipitation eliminate the retardation when the strain was increased to a certain extent. Under heavy deformation, ferrite grains and granular cementites in vanadium microalloyed steel were finer compared with vanadium free steel.
Abstract: Investigation on the casting, hot-rolling and heat treatment process of a high boron-bearing advanced high strength steel was conducted. The scanning electron microscopy (SEM), electron-probe micro-analyzer (EPMA), electron backscattered diffraction (EBSD) and X-ray diffraction (XRD) were employed to analyze the evolution of microstructure which includes the phase constitution and boride morphology during hot processing. Through the control of as-casted, heat treated microstructure and using interrupted tensile tests, the strengthening mechanism was revealed. Results showed that, the strain-induced ferrite transformation of austenite and grain size were the decisive factors which control the strength and ductility, while the defects and internal stress etc. were the secondary factors.
Abstract: In present day manufacturing industries playing the major role in the machining of new materials with complex shapes, intricate structure and difficult profiles. The improvement of industries and machines is accountable for product quality and accuracy, which are not satisfied in conventional machining techniques. The WEDM is advanced machining process, they are capable to machining the components which are difficult to machine, whereas Dry-WEDM is another method, it utilizes the gas instead of dielectric liquid, it exhibits lower corrosion, fine finish, decrease dielectrics and environment friendly. Development of WEDM is suitable machining option for meeting the demands of modern tool room application and metal cutting industries. The purpose of the article attempts is to highlights the application, improvement and future scope of Dry-WEDM and WEDM in industrial areas.
Abstract: Thermal buckling of new model of functionally graded (FG) sandwich beams is presented in this study. Material properties and thermal expansion coefficient of FG sheets are assumed to vary continuously along the thickness according to either power-law (P-FGM) or sigmoid function (S-FGM) in terms of the volume fractions of the constituents. Equations of stability are derived based on the generalized higher-order shear deformation beam theory. Thermal loads are supposed to be constant, linear or nonlinear distribution along the thickness direction. An accurate form solution for nonlinear temperature variation through the thickness of S-FGM and P-FGM sandwich beams is presented. Numerical examples are presented to examine the influence of thickness ratio, the inhomogeneity parameter and the thermal loading kinds on the thermal buckling response of various types of FG sandwich beams.
Abstract: Jute fabrics reinforced Polypropylene (PP) matrix composite was fabricated by compression molding and Unsaturated Polyester Resin (UPR) matrix composites were also fabricated by hand lay-up technique. The fiber content of the composites was 40% by weight. Mechanical properties between two types of composites were compared. Tensile Strength (TS), Tensile Modulus (TM), Elongation at break (Eb%) , and Impact Strength (IS) of the jute fabrics/PP composites were found to be 47 MPa, 1.2 GPa, 13% and 8 kg/cm, respectively. On the other hand, TS, TM, Eb%, and IS of the jute fabrics/UPR composite were found to be 43 MPa, 1.3 GPa, 10% and 6 kg/cm, respectively. It was found that both composites showed almost similar mechanical properties. After tensile testing, fracture sides of both types of the composites were studied by Scanning Electron Microscope (SEM) and the results revealed poor fiber matrix adhesion for jute fabrics with PP and UPR. The fabricated composites became partly biodegradable because of jute (natural fiber) and mechanical properties of both types of composites showed promising results for commercial applications.
Abstract: This paper represents a comparative study of the different weave structures of jute woven fiber reinforced unsaturated polyester resin (UPR) composites. The weave structures were selected as plain (1/1), twill (2/1), twill (3/1) and basket (2/2). Composites (50% fiber by wt.) were prepared by using hand lay-up technique. The mechanical properties such as tensile strength (TS), bending strength (BS) and impact strength (IS) of the composites were evaluated and compared. It was found that basket weave/UPR based composite showed the highest mechanical properties. The optimum value of TS, BS, TM, BM and IS of the composite were found to be 47 MPa, 80 MPa, 1.4 GPa, 4.8 GPa and 27 KJ/m2.To find out the effect of yarn density on mechanical properties of the composites, 2/1 twill structure was selected and found significant improvement in the mechanical properties with the increase of Ends/Inch (EPI) and Picks/Inch (PPI) in the fabric. Water uptake and degradation behavior in aqueous medium of the composites was also observed.
Abstract: The high energy consumption of buildings in the various sectors of society, the exploitation of natural resources and the use of fossil fuels make it necessary to research constructive alternatives that can reduce the impact on the planet. The use of thermal insulation in buildings is important for the reduction of energy consumption, however, most of the materials developed are manufactured generating high rates of pollution. This study starts with the use of natural elements (corn cob / soybean straw / pine bark) and innovative elements (vacuum / slimstone plate), in order to improve energy efficiency of buildings. The methodological development of the work began in the selection of materials and development of facade cladding boards. The determination of the thermal conductivity was analyzed using a heating plate and PT100 temperature sensors, determination of the apparent and actual density, and analysis of the material composition using Scanning Electron Microscopy (SEM). After the development of the analyzes, the natural slabs and recycled slimstone showed significant results, with thermal conductivity lower than 0.07 W / m.k.