Ngoc Binh Duong, Q. Vu, T. Vu, Cuong Doan, H. Tran
Thermodynamic and experimental studies was carried out on the process of Thanhhoa dolomite reduction to produce magnesium. Thermodynamically studied on the effect of pressure and temperature on reduction was carried out together with verification experiment. Results show that at appropriate temperature and vacuum pressure, Thanhhoa dolomite can be reduced using ferrosilicon as the reductant. The higher level of vacuum, the lower temperature required for reduction. Thermodynamic calculation pointed out that at a vacuum pressure of 600 Pa, the reduction temperature could be as low as 1140 °C. Experiment results indicated that at although reduction could be done at 1150 °C, the process efficiency was low, generally below 20%. Process efficiency enhanced as temperature increase and reaches the highest value of 85,8% at 1250 °C (25 wt.% ferrosilicon). The amount of ferrosilicon used also has influenced the process efficiency. After three hours of reduction, the obtained magnesium was very high in purity, 99.3%.
{"title":"SILICOTHERMIC REDUCTION OF THANHHOA DOLOMITE: THERMODYNAMIC AND EXPERIMENTAL","authors":"Ngoc Binh Duong, Q. Vu, T. Vu, Cuong Doan, H. Tran","doi":"10.36547/ams.27.3.948","DOIUrl":"https://doi.org/10.36547/ams.27.3.948","url":null,"abstract":"Thermodynamic and experimental studies was carried out on the process of Thanhhoa dolomite reduction to produce magnesium. Thermodynamically studied on the effect of pressure and temperature on reduction was carried out together with verification experiment. Results show that at appropriate temperature and vacuum pressure, Thanhhoa dolomite can be reduced using ferrosilicon as the reductant. The higher level of vacuum, the lower temperature required for reduction. Thermodynamic calculation pointed out that at a vacuum pressure of 600 Pa, the reduction temperature could be as low as 1140 °C. Experiment results indicated that at although reduction could be done at 1150 °C, the process efficiency was low, generally below 20%. Process efficiency enhanced as temperature increase and reaches the highest value of 85,8% at 1250 °C (25 wt.% ferrosilicon). The amount of ferrosilicon used also has influenced the process efficiency. After three hours of reduction, the obtained magnesium was very high in purity, 99.3%.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46733795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, theoretical modeling of the thermodynamic processes of the release of excess phases is carried out, as well as a practical study of the structure and distribution of chemical elements in carbides, depending on alloying using a scanning electron microscope. The obtained dependences were experimentally confirmed using X-ray spectroscopy on nickel-based superalloys. It is recommended to use the obtained mathematical models not only in the design of new nickel-based superalloys, but also in the improvement of known brand compositions within the declared concentrations.
{"title":"MODELING OF CARBIDES COMPOSITION IN WELDED ALLOY SYSTEM Ni-34Cr-4,3W-2,3Mo-1,3Al-1,3Ti-1,3Nb-0,1C","authors":"A. Glotka, V. Ol’shanetskii","doi":"10.36547/ams.27.3.1049","DOIUrl":"https://doi.org/10.36547/ams.27.3.1049","url":null,"abstract":"In this work, theoretical modeling of the thermodynamic processes of the release of excess phases is carried out, as well as a practical study of the structure and distribution of chemical elements in carbides, depending on alloying using a scanning electron microscope. The obtained dependences were experimentally confirmed using X-ray spectroscopy on nickel-based superalloys. It is recommended to use the obtained mathematical models not only in the design of new nickel-based superalloys, but also in the improvement of known brand compositions within the declared concentrations.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47332036","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Nguyen, V. T. Doan, Trung Van Trinh, Huy Van Vu
AISI 420 stainless steel is widely used in applications where wear and corrosion resistance are required. However, the heat treatment and nitriding process can drastically reduce the corrosion resistance of this stainless steel. This article focuses on investigating the influence of steel substrate and gas nitriding efficiency at two temperatures of 520 oC and 550 oC on some properties of CrN coating. The experiments were carried out to evaluate the surface hardness, microstructure and phase composition of nitrided layers. The coating adhesion and load capacity of the coating were performed according to VDI 3198 standard. Electrochemical testing was performed in a solution of 3.5% NaCl and then using the Tafel method to determine the corrosion current and corrosion potential. The thickness of CrN and CrN/CrN coating was 1.6 μm and 3 μm, respectively. The study showed that the corrosion resistance of coatings fabricated through duplex technology was affected not only by the normal defects but also by the porosity on the nitrided surface. The corrosion resistance of multilayer duplex coating was improved compare with mono-layer duplex coating due to its ability to cover and reduce pores and pitting defects.
{"title":"CHARACTERISTICS OF AISI 420 STAINLESS STEEL MODIFIED BY COMBINING GAS NITRIDING AND CrN COATING","authors":"T. Nguyen, V. T. Doan, Trung Van Trinh, Huy Van Vu","doi":"10.36547/ams.27.3.1035","DOIUrl":"https://doi.org/10.36547/ams.27.3.1035","url":null,"abstract":"AISI 420 stainless steel is widely used in applications where wear and corrosion resistance are required. However, the heat treatment and nitriding process can drastically reduce the corrosion resistance of this stainless steel. This article focuses on investigating the influence of steel substrate and gas nitriding efficiency at two temperatures of 520 oC and 550 oC on some properties of CrN coating. The experiments were carried out to evaluate the surface hardness, microstructure and phase composition of nitrided layers. The coating adhesion and load capacity of the coating were performed according to VDI 3198 standard. Electrochemical testing was performed in a solution of 3.5% NaCl and then using the Tafel method to determine the corrosion current and corrosion potential. The thickness of CrN and CrN/CrN coating was 1.6 μm and 3 μm, respectively. The study showed that the corrosion resistance of coatings fabricated through duplex technology was affected not only by the normal defects but also by the porosity on the nitrided surface. The corrosion resistance of multilayer duplex coating was improved compare with mono-layer duplex coating due to its ability to cover and reduce pores and pitting defects.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45649726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Nikitasari, A. Royani, G. Priyotomo, S. Sundjono
The research aims to study the effect of flow rate and temperature on corrosion rate of carbon steel pipe in condensate solution from geothermal power plant. The corrosion rate in this study highlighted by electrochemical measurement. Electrochemical measurement performed in two conditions i.e stagnant and dynamic conditions. There are three kinds of temperature used in this research : 30oC, 40oC, and 50oC. Modification of corrosion cell installed for dynamic condition with flow rate variations : 0.27 m/s; 0.6 m/s; 1 m/s; 1.5 m/s; and 1.9 m/s. It was found that corrosion rate boosts with temperature and fluid flow rate in condensate solution of geothermal power plant. The highest corrosion rate (38 mpy) obtained at 50oC and 1.9 m/s of flow rate.
{"title":"EFFECT OF FLOW RATE AND TEMPERATURE ON CORROSION RATE OF CARBON STEEL PIPE IN CONDENSATE SOLUTION FROM GEOTHERMAL POWER PLANT","authors":"A. Nikitasari, A. Royani, G. Priyotomo, S. Sundjono","doi":"10.36547/ams.27.3.1005","DOIUrl":"https://doi.org/10.36547/ams.27.3.1005","url":null,"abstract":"The research aims to study the effect of flow rate and temperature on corrosion rate of carbon steel pipe in condensate solution from geothermal power plant. The corrosion rate in this study highlighted by electrochemical measurement. Electrochemical measurement performed in two conditions i.e stagnant and dynamic conditions. There are three kinds of temperature used in this research : 30oC, 40oC, and 50oC. Modification of corrosion cell installed for dynamic condition with flow rate variations : 0.27 m/s; 0.6 m/s; 1 m/s; 1.5 m/s; and 1.9 m/s. It was found that corrosion rate boosts with temperature and fluid flow rate in condensate solution of geothermal power plant. The highest corrosion rate (38 mpy) obtained at 50oC and 1.9 m/s of flow rate.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46463825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Stornelli, Damiano Gaggia, M. Rallini, A. Di schino
Laser Powder Bed Fusion (L-PBF) is a widespread additive manufacturing technology in industrial applications, for metal components manufacturing. Maraging steel is a special class of Fe-Ni alloys, typically used in the aerospace and tooling sectors due to their good combination of mechanical strength and toughness. This work analyses the heat treatment effect on the microstructure and hardness value of 300-grade maraging steel manufactured by the L-PBF process. The considered heat treatment consists of a solution annealing treatment followed by quenching and ageing hardening treatment. The effect of ageing temperature is reported, in a wide temperature range. Results show that solution annealing treatment fully dissolves the solidification structure caused by the L-PBF process. Moreover, the ageing hardening treatment has a significant impact on the hardness, hence on strength, of L-PBF maraging steel. The optimal ageing conditions for the L-PBF maraging steel are identified and reported: in particular, results show that the hardness of 583 HV is achieved following ageing treatment at 490 °C for 6 hours. A higher treatment temperature leads to over-ageing resulting in a decrease of hardness. Conversely, an excessive ageing time does not seem to affect the hardness value, for the ageing temperature of 490 °C.
{"title":"HEAT TREATMENT EFFECT ON MARAGING STEEL MANUFACTURED BY LASER POWDER BED FUSION TECHNOLOGY: MICROSTRUCTURE AND MECHANICAL PROPERTIES","authors":"G. Stornelli, Damiano Gaggia, M. Rallini, A. Di schino","doi":"10.36547/ams.27.3.973","DOIUrl":"https://doi.org/10.36547/ams.27.3.973","url":null,"abstract":"Laser Powder Bed Fusion (L-PBF) is a widespread additive manufacturing technology in industrial applications, for metal components manufacturing. Maraging steel is a special class of Fe-Ni alloys, typically used in the aerospace and tooling sectors due to their good combination of mechanical strength and toughness. This work analyses the heat treatment effect on the microstructure and hardness value of 300-grade maraging steel manufactured by the L-PBF process. The considered heat treatment consists of a solution annealing treatment followed by quenching and ageing hardening treatment. The effect of ageing temperature is reported, in a wide temperature range. Results show that solution annealing treatment fully dissolves the solidification structure caused by the L-PBF process. Moreover, the ageing hardening treatment has a significant impact on the hardness, hence on strength, of L-PBF maraging steel. The optimal ageing conditions for the L-PBF maraging steel are identified and reported: in particular, results show that the hardness of 583 HV is achieved following ageing treatment at 490 °C for 6 hours. A higher treatment temperature leads to over-ageing resulting in a decrease of hardness. Conversely, an excessive ageing time does not seem to affect the hardness value, for the ageing temperature of 490 °C.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48765968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper the effect of quenching and tempering (Q&T) thermal treatment on mechanical properties of a novel 6.5% Cr steel for forged components is studied. The main innovation is in the increased hardenability following the higher Cr content with respect to the more common 5% Cr steel allowing to lower the content of other chemical elements aimed to achieve the target mechanical properties. Following to the high intrinsic hardenability of such steel based on the Cr content a poor effect of prior austenite grain size should be expected after quenching. Aim of this work is to evaluate such effect and to analyse the dependence of mechanical properties on it.
{"title":"EFFECT OF AUSTENITIC GRAIN SIZE ON THE PHASE TRANSFORMATION OF A NOVEL 6.5% Cr STEEL FOR FORGED COMPONENTS","authors":"A. Di schino","doi":"10.36547/ams.25.1.3","DOIUrl":"https://doi.org/10.36547/ams.25.1.3","url":null,"abstract":"In this paper the effect of quenching and tempering (Q&T) thermal treatment on mechanical properties of a novel 6.5% Cr steel for forged components is studied. The main innovation is in the increased hardenability following the higher Cr content with respect to the more common 5% Cr steel allowing to lower the content of other chemical elements aimed to achieve the target mechanical properties. Following to the high intrinsic hardenability of such steel based on the Cr content a poor effect of prior austenite grain size should be expected after quenching. Aim of this work is to evaluate such effect and to analyse the dependence of mechanical properties on it.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2021-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43472495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Intermetallic compounds (IMCs) formation between lead-free solder alloys (Sn-9Zn and Sn-8Zn-3Bi) and Ni/Au surface finish copper substrate were studied. Reaction between the solder and the substrate was carried out at regular soldering temperature, approx. 50 °C above the melting temperature of the solder alloys. Results indicated that Au-Zn was the IMC formed at the interface and the Au layer which is electro-plated on the substrate has completely dissolved into the solder alloys. The amount of Au available at the interface is an important factor that influent the morphology of the IMC with thicker Au layer on the substrate resulted in thicker layer of IMC at the interface. Although Bi does not taken part in the composition of IMC, it influent the formation of IMC, the IMC formed in the Sn9Zn/substrate interface was Au5Zn3, meanwhile it was g2-AuZn3 in the Sn-8Zn-3Bi/substrate interface.
{"title":"INTERMETALLIC COMPOUNDS FORMATION OF SOLDER ALLOYS ON Ni/Au SURFACE FINISH COPPER","authors":"Ngoc Binh Duong","doi":"10.36547/ams.26.4.707","DOIUrl":"https://doi.org/10.36547/ams.26.4.707","url":null,"abstract":"Intermetallic compounds (IMCs) formation between lead-free solder alloys (Sn-9Zn and Sn-8Zn-3Bi) and Ni/Au surface finish copper substrate were studied. Reaction between the solder and the substrate was carried out at regular soldering temperature, approx. 50 °C above the melting temperature of the solder alloys. Results indicated that Au-Zn was the IMC formed at the interface and the Au layer which is electro-plated on the substrate has completely dissolved into the solder alloys. The amount of Au available at the interface is an important factor that influent the morphology of the IMC with thicker Au layer on the substrate resulted in thicker layer of IMC at the interface. Although Bi does not taken part in the composition of IMC, it influent the formation of IMC, the IMC formed in the Sn9Zn/substrate interface was Au5Zn3, meanwhile it was g2-AuZn3 in the Sn-8Zn-3Bi/substrate interface.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43462184","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Szczęsny, D. Kopyciński, E. Guzik, G. Soból, K. Piotrowski, P. Bednarczyk, Władysław Paul
In industrial conditions, ductile iron was prepared and two molds were made, in which a 600mm thick plate was formed. Filling system for one mold was placed vertically and for the second -horizontally. In order to obtain cooling curves, "S" type thermocouples have been placed in the mold. After cooling the casts, the samples from the fixing points of thermocouples were cut by the trepanning method. In the "vertical" cast sample shrinkage porosity was observed, while in the "horizontal" cast sample no porosity was detected. A significant difference in the recorded temperature in the center of the casts was discovered, indicating a defect in "vertical" cast.
{"title":"SHAPING OF DUCTILE CAST IRON DEDICATED FOR SLAG LADLE","authors":"A. Szczęsny, D. Kopyciński, E. Guzik, G. Soból, K. Piotrowski, P. Bednarczyk, Władysław Paul","doi":"10.36547/ams.26.2.312","DOIUrl":"https://doi.org/10.36547/ams.26.2.312","url":null,"abstract":"In industrial conditions, ductile iron was prepared and two molds were made, in which a 600mm thick plate was formed. Filling system for one mold was placed vertically and for the second -horizontally. In order to obtain cooling curves, \"S\" type thermocouples have been placed in the mold. After cooling the casts, the samples from the fixing points of thermocouples were cut by the trepanning method. In the \"vertical\" cast sample shrinkage porosity was observed, while in the \"horizontal\" cast sample no porosity was detected. A significant difference in the recorded temperature in the center of the casts was discovered, indicating a defect in \"vertical\" cast. \u0000 ","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45802621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by in situ reactive sintering of the initial powder mixture B4C-Al with concentration from 5 to 25 wt.% Al sintering additives. The composite samples were hot pressed at the temperature of 1850 °C, pressure of 35 MPa, for 15 min in a vacuum atmosphere. The portion of Al8B4C7 secondary phase increased from 3.3 to 22.1 wt.% when increasing the concentration of Al sintering additive from 5 to 25 wt.% Al. Significant improving of densification and mechanical properties was measured at increasing of Al sintering additive concentration from 5 to 10 wt.% Al. The highest average hardness of 28.74 GPa was achieved when adding 15 wt.% Al sintering additive. The fracture toughness increased with concentration of Al sintering additive in whole concentration range with the highest average value of 5.92 MPa.m1/2 at 25 wt.% Al sintering additives.
{"title":"BORON CARBIDE BASED CERAMIC COMPOSITES HOT PRESSED WITH ALUMINIUM ADDITIVE","authors":"P. Švec, Z. Gábrišová, A. Brusilová, Ľ. Čaplovič","doi":"10.36547/ams.26.2.529","DOIUrl":"https://doi.org/10.36547/ams.26.2.529","url":null,"abstract":"Ceramic composite materials consisting of B4C matrix and Al8B4C7 secondary phase were prepared by in situ reactive sintering of the initial powder mixture B4C-Al with concentration from 5 to 25 wt.% Al sintering additives. The composite samples were hot pressed at the temperature of 1850 °C, pressure of 35 MPa, for 15 min in a vacuum atmosphere. The portion of Al8B4C7 secondary phase increased from 3.3 to 22.1 wt.% when increasing the concentration of Al sintering additive from 5 to 25 wt.% Al. Significant improving of densification and mechanical properties was measured at increasing of Al sintering additive concentration from 5 to 10 wt.% Al. The highest average hardness of 28.74 GPa was achieved when adding 15 wt.% Al sintering additive. The fracture toughness increased with concentration of Al sintering additive in whole concentration range with the highest average value of 5.92 MPa.m1/2 at 25 wt.% Al sintering additives.","PeriodicalId":44511,"journal":{"name":"Acta Metallurgica Slovaca","volume":" ","pages":""},"PeriodicalIF":1.0,"publicationDate":"2020-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48600287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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