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Acta Metallurgica Slovaca
Number of Followers: 1  Open Access journalISSN (Print) 1335-1532 - ISSN (Online) 1338-1156 Published by SciCell s.r.o.  [5 journals]
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- CORROSION BEHAVIOR OF Al/SiC/PKSA HYBRID COMPOSITES IN 1.0 M H2SO4
ENVIRONMENT USING POTENTIODYNAMIC POLARIZATION TECHNIQUE
Authors: Peter Ikubanni, Makanjuola Oki, Adekunle Adeleke, Emmanuel Ajisegiri, Moses Fajobi
Pages: 169 - 171
Abstract: The potentiodynamic polarization of aluminium 6063 alloy reinforced with silicon carbide (SiC) and palm kernel shell ash (PKSA) particulates at various mixing ratios were investigated. Double stir casting method was adopted for the production of the hybrid reinforced composites. The existence of the reinforcements within the matrix alloy acted as active sites for corrosion initiation. Hence, pitting corrosion was observed. The range of values for Ecorr and Icorr obtained at 24 h in 1.0 M H2SO4 were between -627.74 and -644.46 mV, and between 423.81 and 860.23 µA/cm2, respectively. The Ecorr values ranged from -654 to -697.22 mV, and the Icorr ranged from 1075.65 to 3057.16 µA/cm2 at 72 h in 1.0 M H2SO4. The relative resistance to corrosion of the samples is dependent on the thin oxide film formed on the surface of the samples.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1561
Issue No: Vol. 28, No. 4 (2022)
- MICROSTRUCTURE AND TENSILE PROPERTIES OF A RECENT INTER-CRITICALLY
AUSTENITIZED QUENCHED AND PARTITIONED STEEL
Authors: Hoda Refaiy, Mai Fouad, Hoda Nasr El-Din, Eman H. El-shenawy
Pages: 172 - 180
Abstract: Quenched and partitioned steel is a promising grade of advanced high-strength steel "Third Generation" for industrial applications such as the automotive industry. This research aimed to develop a novel ultra-high-strength quenched and partitioned steel with good ductility from a novel alloy with the composition of 0.37C- 3.65Mn- 0.65Si- 0.87Al- 1.5Ni-0.05P, wt.% which is non-standard. This quenched and partitioned steel was developed by inter-critical austenitization followed by quenching to a temperature below Martensite start temperature (80 and 120 oC), then partitioning at 450 oC for different times (20, 40, 60, 100, 140, and 180 s). Scanning electron microscope and X-Ray diffraction were utilized to investigate the microstructure and retained austenite characteristics. The tensile properties of developed Q&P specimens were also investigated. The results demonstrated that the specimen quenched at 120 oC and partitioned for 180s achieved a maximum strength elongation balance of 26 GPa.%. Both the specimens quenched at 80 and 120 oC displayed a decrease in strength values with extending holding time due to the tempering of primary martensite. Increasing partitioning time for the specimens quenched at 120 oC led to enhancing elongation, where a maximum total elongation of 19.7% was achieved for the partitioning time of 180s.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1578
Issue No: Vol. 28, No. 4 (2022)
- Effects of aluminium addition and austempering temperatures on Al-alloyed
ductile iron microstructure and mechanical properties
Authors: Abdullahi Adebayo, Olawale Ajibola, Oluwasegun Falodun, Sunday Borisade, Adebayo Owa, Oluwole Adigun, Akinlabi Oyetunji, Kenneth Alaneme
Pages: 181 - 187
Abstract: The research investigates the effect of varying amounts of aluminium (1.05, 1.575, 2.29, 3.02 and 3.74 wt.%) addition and heat treatment (austempering at 300, 350, 400 oC) on the microstructure and mechanical properties of ductile cast iron alloys. The graphitizing effects of the Al alloy and varied austempering temperatures on hardness, tensile strength, and impact toughness of the ductile cast iron (DCI) were evaluated. The results of the influences of Al addition and heat treatment on the properties of the DCI determined were presented as graphical data while the microstructures were done by using a scanning electron microscope (SEM). The microstructures revealed that the addition of Al into the matrix brings about the precipitation of ferrite around the graphite nodules. The combined effects of the increase Al content and austempering temperatures produced greater hardness values on the Al-alloyed DCI samples than the as-cast sample. The hardness value for the entire sample ranged between 27.25 to 57.03 BHN. Tensile strength increased with an increase in Al content and lower austempering temperatures, whereas, the impact toughness increased with an increase in Al content and higher austempering temperature.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1598
Issue No: Vol. 28, No. 4 (2022)
- GRAIN SIZE EVOLUTION, MECHANICAL AND CORROSION BEHAVIOUR OF PRECIPITATE
STRENGTHENED Cu-Ni ALLOY
Authors: Cynthia Nwaeju, Amarachukwu Eboh, Francis Edoziuno
Pages: 188 - 196
Abstract: Grain size characteristics, mechanical properties, and corrosion resistance of Cu-10%Ni alloy heat treated at three different temperatures and times were investigated and compared with the synthesized alloy. Mechanical properties such as UTS, ductility, hardness, and impact strength were determined. An optical metallurgical microscope was used to examine the structural properties. ImageJ software was also used to measure the grain size distribution of the alloys. The corrosion behaviour of the produced Cu-10%Ni alloys is analyzed by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). After corrosion testing, the surface morphology of the exposed samples is analyzed by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy. The corrosion rate of precipitate strengthened Cu-10%Ni alloy decreases and ultimate tensile strength, ductility, and hardness increase as the average grain size distribution decreases. The non-heat treated Cu-10%Ni alloy showed a peak value of corrosion rate and average grain size, but a lower value of mechanical properties. An increase in residual stress follows an increase in grain size distribution, which lowers the strength and increases corrosion rates due to more active sites. The research outcome has enabled the improvement of the mechanical and corrosion properties of Cu-10%Ni alloys as a component for marine and automobile applications.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1609
Issue No: Vol. 28, No. 4 (2022)
- DECREASING MECHANICAL PROPERTIES OF THE SUPERHEATER STEEL GRADE P22 HEATED
AT ELEVATED TEMPERATURE UNDER CONSTANT STRESS
Authors: Anh-Hoa Bui, Cao-Son Nguyen, Thu-Hien Nguyen
Pages: 197 - 202
Abstract: This paper investigated change of the mechanical properties of the superheater pipe steel grade P22 (ASTM A335) under constant stress of 9.68 MPa and various temperatures of 500-700 oC. The steel specimens were prepared from the new steel pipe taken from a coal-fired power plant in Vietnam, then heated to the given temperature and held for the predetermined time as 24, 48 and 72 hours in the atmosphere. The results showed that the mechanical properties of the steel P22 decreased with the increased temperature and time. This deterioration of the steel strength was caused by the redistribution of the carbide in the steel subjected under the elevated temperature and the constant stress. Although change in the microstructure including phase and grain size was not observed, the SEM micrographs showed that the carbide of the heated steel accumulated on the grain boundaries and the triple regions when the temperature and holding time increased. This phenomenon was attributed to reduce number of the carbide in the steel, resulting in decrease of the mechanical properties. The obtained results indicated that decrease of the mechanical properties of the steel pipe P22 can occur in the early period of working time in the practice.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1610
Issue No: Vol. 28, No. 4 (2022)
- CIRCULAR ECONOMY APPLIED TO METHANE PRODUCTION FROM NATURAL GAS HYDRATE
RESERVOIRS: POTENTIALITIES OF RESIDUAL DUST COMING FROM STEEL PLANTS
Authors: Giulia Stornelli, Alberto Maria Gambelli, Andrea Di Schino, Guido Zucca, Federico Rossi
Pages: 203 - 207
Abstract: Natural gas hydrate represents one of the most promising solutions to answer to the constantly increasing energy demand; in addition, the possibility of recover methane via carbon dioxide injection, with a theoretical exchange ratio equal to 1, makes it a potential carbon neutral energy source. Among them, energetical costs associated to practical operations in marine deposits. The use of chemical inhibitors and or promoters to improve the exchange process is gaining increasing interest and researchers are mainly focused on finding less environmental unfriendly additives and on reducing their costs. In that direction, the present work deals with the possible use of waste dust, produced during steel mill processes, as promoter of the CO2/CH4 replacement process. That sand commonly contains a great variety of compounds, such as metal oxides, alumina, salts, and so on. Some of them have a chemical composition close to well-known hydrate inhibitors/promoters. Moreover, that application could be a further energetic cycle for a waste product. In this work, both methane and carbon dioxide hydrate formation were tested in absence and in presence of cupper oxides, with different concentrations. Hydrate formation and dissociation results where then compared among each other and with hydrate equilibrium values for those compounds.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1632
Issue No: Vol. 28, No. 4 (2022)
- ADDITIVE MANUFACTURING: A NEW CONCEPT FOR END USERS. THE CASE OF MAGNETIC
MATERIALS
Authors: Andrea Di Schino, Giulia Stornelli
Pages: 208 - 211
Abstract: Metal additive manufacturing (AM) technology is growing up as a technology. Although up today slower and less reliable than traditional production methods, AM systems are showing to be very successful when producing parts with unconventional topologies or in small quantities. In addition, it is showing its capability to produce components with chemical compositions which should not be realized with standard production processes. In this paper some examples are reported of magnetic materials specifically designed for AM. In this work, powder of FeSi electric steel, with 6.5 wt.% Si content is considered to produce samples by AM. Aim of this paper is to investigate the microstructural and texture evolution of FeSi steels, with 6.5% Si, following annealing heat treatment, with the aim of identifying the conditions under which it could be possible to obtain the best magnetization behavior of the alloys.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1648
Issue No: Vol. 28, No. 4 (2022)
- EFFECT OF RETAINED AUSTENITE ON PLASTIC CHARACTERISTICS OF DUAL PHASE
STEELS
Authors: Peter Prislupčák, Tibor Kvačkaj, Jana Bidulská, Stanislav Németh, Mária Demčáková, Roman Gburík, Vladimír Kundracík
Pages: 212 - 218
Abstract: In terms of the current trend of research and development of new materials and optimization of current materials in the automotive industry, the greatest attention is paid to progressive high-strength dual-phase (DP) steels with increased stampability, which are designed for cold stamping for specific internal car body components of the current market. New grades of DP steels provide a combination of high strength and good formability and contribute to the weight savings of vehicle parts by 10 to 20 %, compared to current DP grades. Thanks to their top properties, DP steels with increased formability can absorb more crash energy using less steel. As a result, high-strength DP780GI and DP780GI-HF materials of first generation (hereinfater DP780GI-HF) were analyzed. The stampability improvement of DP steels was demonstrated by the experimentally determined Forming Limit Curves for both steels.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1653
Issue No: Vol. 28, No. 4 (2022)
- NUMERICAL AND EXPERIMENTAL STUDIES ON CLINCH-BONDED HYBRID JOINING OF
STEEL SHEET DX53D+Z
Authors: Ľuboš Kaščák, Denis Cmorej, Ján Slota, Emil Spišák, Ján Varga
Pages: 219 - 223
Abstract: The automotive industry is characterized by the fact that it uses an entire range of materials. These are materials with different mechanical properties, thicknesses, and even different combinations. A variety of joining methods, such as clinching, is used to join this range of materials. However, sometimes it is necessary to combine several methods of joining materials. The paper deals with the evaluation of the properties of joints, which are created by a combination of mechanical joining and adhesive bonding. Two types of adhesives were used: adhesive based on epoxy resin and adhesive based on acrylate polymers. Double-sided hot-dip galvanized steel sheets DX53D+Z with a thickness of 0.8 mm were used to join with this combination of joining techniques. Numerical simulation tools were used to assess the joinability of materials. The simulation results were verified by the results from the experiments of real test samples. Samples joined by the clinching method combined with epoxy resin adhesives achieved higher load-bearing values and no cracks or any other type of failures were observed in these joints.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1657
Issue No: Vol. 28, No. 4 (2022)
- HRPD and TEM Study of P/M 58Fe17Cr25Ni Austenitic Stainless Steel
Synthesized by Spark Plasma Sintering
Authors: Salim Mustofa, M Dani, Parikin Parikin, Toto Sudiro, Bambang Hermanto, D. R. Adhika, Andon Insani, Syahbuddin Syahbuddin, Takanori Hino, C. A. Huang
Pages: 224 - 229
Abstract: 58Fe17Cr25Ni austenite stainless steel has been fabricated using metal powder through sintering with a spark plasma at temperatures of 900 and 950°C for 5 minutes. High purity Fe, Ni and Cr powders were used as materials for this steel. Before sintering, the powder was mixed in a milling equipment which was processed for 5 hours, then it is formed into a coin by pressing it under a load of 25 tons. High resolution powder neutron diffractometer was used for identifying the crystal structure in the 58Fe17Cr25Ni austenitic stainless steel. The sintering process at temperatures of 900C and 950°C generally forms microstructure having matrix of equiaxed austenite grains, with a crystal structure of face-centered cubic which included in the Fm3m space group. Some particles with high Cr content, a'-Cr, are distributed in all austenite grains. The austenite grains seen in the 58Fe17Cr25Niaustenitic stainless steel sintered at 900°C are twin grains. Dislocations, slip planes and bands are also existed in those grains. These defects are expected to decrease with increasing sintering temperatures up to 950° C. This change was followed by the appearance of air bubbles and sub-grains as the dominant sub-structures in the 58Fe17Cr25Ni austenitic stainless steel sintered at 950°C.
PubDate: 2022-12-13
DOI: 10.36547/ams.28.4.1548
Issue No: Vol. 28, No. 4 (2022)
