The influence of continuous casting technology on the cleanliness of carbon steel

The influence of the production method, i.e. casting technology on the cleanliness and thus the quality of carbon steels is best determined through the presence and type of non-metallic inclusions. A large number of inclusions, especially oxide and complex ones, can significantly affect the mechanical properties of carbon steels and limit their application for the production of finished products. This paper presents the influence of the presence, type and amount of non - metallic inclusions in B500B carbon steel according to ASTM / AISI produced by continuous casting technology without and with the application of stream protection.

Multi response parameters optimization of ZA-27 nanocomposites

In this study, Taguchi-Grey relational analysis was used to investigate and optimize wear parameters such as sliding speed, reinforcement of Gr and reinforcement of Al2O3, and their effect on dry sliding wear performance of ZA-27 nanocomposites. Nanocomposites were synthesized via hot pressing process with pre-processing mechanical milling. Sixteen experimental tests were performed based on design of experiments which was created with the help of Taguchi L16 orthogonal array. Grey relational analysis (GRA) was applied for determination of optimal combination of parameters in order to improve tribological characteristics. Optimal combination of factors, obtained with Taguchi Grey relational analysis was sliding speed of 100 rpm, reinforcement content of 1 vol.% Gr and reinforcement content of 4 vol.% Al2O3. Validation of results was done by using Artificial Neural Network (ANN). Developed model had overall regression coefficient 0.99836, and output values showed good correlation with experimental results. Based on this research, it can be observed that nanocomposites with reinforcement of Gr and Al2O3 can be potentially employed in many industries as a good substitute for the base alloy. In addition, as a result of the analysis of the worn surfaces, it was determined that with the increase of the Al2O3 ratio, the hard Al2O3 nanoparticles turned the dominant wear mechanism into abrasive. Also, it was determined that the Gr nanoparticles appeared on the abrasive wear lines.

Comparative studies on the microstructure and corrosion behaviour of forged and SLM processed 316L stainless steel

The corrosion behaviour of forged and SLM (Selective Laser Melting) processed 316L samples was investigated in a 3.5% NaCl solution at neutral and light acidic pH. The influence of the oxygen concentration in the testing solution on the corrosion resistance of the alloy was also proved. This made it possible to qualitatively evaluate the influence of the additive manufacturing process on the microstructure of the 316L alloy in comparison to that of the forged steel. Therefore, the logarithmic polarisation curves generated during the electrochemical investigations were compared, especially in respect to the corrosion potential respectively corrosion current density. The results showed that the corrosion resistance of the 3D-printed samples was inferior to that of the forged 316L. Instead of the pitting corrosion that often appears during exposure of the forged material to chloride containing media, the SLM processed material exhibited rather an extensive surface attack. The microscopic examination of the samples revealed large differences in porosity between the microstructures obtained by means of the two manufacturing methods, whereby the 3D-printed samples exhibited a larger number of voids.

The material selection of the heating plates used in the vulcanization process obtained using different MCDM methods

The material selection problem is one of the most important steps in the development process of a part of any subassembly assembly, machine, product, etc. The material selection process needs a systematic and time-consuming approach to choose the optimal material to satisfy the product’s requirements. That is to say, many confronting criteria and possible material types (alternatives) available, makes this problem Multi-Criteria Decision-Making problem (MCDM). This paper shows the applicability of the MCDM methodology in the material selection problem for steam heating plates for the vulcanization process used in the inner tube manufacturing process. Specifically, the criteria weights are obtained by CRITIC (Criteria Importance Through Intercriteria Correlation), ENTROPY and PIPRECIA (Pivot Pairwise Relative Criteria Importance Assessment) methods, while TOPSIS (Technique for the Order Preference by Similarity to Ideal Solution) method has been implemented in this process for evaluation and ranking of the possible alternatives (material types).

Porosity distribution in metal injection molded parts

Metal injection molding technology is commonly used in production of small and very complex parts. Residual porosity is unavoidable characteristic of P/M parts, affecting their final properties. During injection molding phase powder-binder separation can occur, causing green density variation through cross section of the part. This behaviour is particularly pronounced as complexity of the parts increases. As a consequence, zones with different density and residual porosity can be seen after sintering. In this regard, porosity and hardness distribution of the sintered ring-shaped part is analysed and presented in the paper.

Influence of the polymer matrix type on cavitation resistance of composites

Cavitation resistance of polymer matrix / basalt powder composites was determined in this work. Two types of composites were tested: epoxy resin / basalt powder composite and polyester resin / basalt powder composite. In both cases, a basalt powder was used as reinforcement in the resin (grain size 20μm, in the amount of 15 wt%). An ultrasonic vibration method with a stationary sample was used to test the cavitation resistance of composites in laboratory conditions. The change in sample mass with test time was monitored to define cavitation rate. Scanning electron microscopy was used to monitor the morphology of composites surface damage.

Development of Hybrid Cellulosic-Keratineous Fibers Base Epoxy Composites for Automobile Applications

The development of hybrid cellulosic-keratinous fibers reinforced epoxy composites was investigated in this study. Hybrid composites were fabricated by mixing coir fiber (CF) and chicken feather fiber (CFF) with the epoxy matrix in a randomly dispersed approach. The mechanical properties such as tensile, flexural and hardness properties were determined. Also, wear property, thermal conductivity and moisture absorption potentials of the developed composites were studied while the surface morphology of the composite fracture surface was examined using scanning electron microscopy (SEM). The results revealed that all the selected properties were improved compared to the unreinforced epoxy matrix. Sample with 1% CF and 2% CFF gave the optimum results and the combination of good mechanical, wear, thermal insulating and moisture resistance properties. It was discovered that higher volume of CFF in synergy with low volume of CF was responsible for performance. The results revealed that the materials can be used in automobile due to the inclusion of light-weight bio-fibers that gave good insulating properties in epoxy composites in conjunction with good mechanical, wear and moisture resistance.

The Effect of Palm Kernel Shell Ash on the Mechanical and Wear Properties of White Cast Iron

This study investigates the influence of palm kernel shell ash (PKSA) on mechanical and wear properties of white cast iron (WCI) particularly its influence on its microstructure, elemental composition, hardness and wear resistance. The PKSA was characterized to determine its elemental composition, and it was found to contain high amount of silicon (Si) and iron (Fe) followed by calcium (Ca) and other trace elements. The cast iron was cast into rods of specific dimension with sand casting method using rotary furnace to re-melt cast iron scrap. The WCI rods were then cut into bits for the various test. Heat treatment operation was carried out to determine its properties. Upon completion of the examinations, it was found that the PKSA increased the cementite phase within the matrix of the cast iron, and reduced the pearlitic phase and graphite formation, which gave it increased hardness, and perfect wear resistance due to the increment in carbon content and reduction in silicon content. Also, upon heat treatment, it was found that the PKSA reduced the pearlitic phase within the matrix of the cast iron, increases the formation of transformed ledeburites, austenitic dendrites and tempered graphite, which lead to increased machinability and ductility as well as to reduced hardness, and wear resistance when compared to non-heat treated samples.

On possibility of binary nanodevices production

The work deals with possibilities of molecular level device production for use in binary data storage and in performing basic logical operations needed for binary data processing. Method of obtaining molecular logic gates through bottom-up production approach, that is, the method of transition from liquid state to solid state nanodevices, has been outlined. In addition, methods of obtaining some devices through combination of top-down and bottom-up production methods, that is the methods of building single nano particle transistors, have been depicted. The devices production justification has been considered through their characteristics such as the devices packing density, switching speed, device ease of addressing, device ease of production, and device concatenability

WAAM and Other Unconventional Metal Additive Manufacturing Technologies

The paper presents an overview of metal additive manufacturing technologies. The emphasis is on unconventional emerging technologies with firm background on welding technologies such as Ultrasonic Additive Manufacturing, Friction Additive Manufacturing, Thermal Spray Additive Manufacturing, Resistance Additive Manufacturing and Wire and Arc Additive Manufacturing. The particular processes are explained in detail and their advantages and drawbacks are presented. Attention is made on materials used, possibilities to produce multi-material products and functionally graded materials, and typical applications of currently developed technologies. The state-of-the-art on the Wire and Arc Additive Manufacturing is presented in more detail due to high research interests, it’s potential and widespread. The main differences between different arc additive manufacturing technologies are shown. An influence of processing parameters is discussed with respect to process stability and process control. The challenges related to path planning are shown together with the importance of post-processing. The main advantage of presented technologies is their ability of making larger and multi-material parts, with high deposition rate, which is difficult to achieve using conventional additive technologies.