Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222575
Rafael Menezes Nunes, Henrique André Heine
{"title":"Análise do retorno elástico do aço ASTM A36 em processos de dobra em V em diferentes velocidades e raios de ferramental","authors":"Rafael Menezes Nunes, Henrique André Heine","doi":"10.4322/2176-1523.20222575","DOIUrl":"https://doi.org/10.4322/2176-1523.20222575","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526149","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222237
Paulo Couceiro, J. Miguel
Highly non-ideal explosives usually react expressively below their ideal velocities of detonation. In these cases, dimensional effects and product heterogeneities become important to proper model their respective detonation state. Although Direct Numerical Simulation (DNS) techniques can provide a complete and exact solution for this problem, their actual computation cost are still not practical for industrial applications. In order to minimize these constrains, a simplified two-dimensional steady non-ideal detonation model for cylindrical stick explosives is presented. Based on an ellipsoidal shock shape approach (ESSA), the proposed model combines the quasi-one-dimensional theory for the axial flow solution with the unconfined sonic post-flow conditions at the edge of the explosive. Once calibrated, the model offers the possibility to predict the non-ideal detonation state for any charge diameter, resulting in a full mapping of the diameter-effect curve of the explosive. In addition, the effect of the inert confiner on the detonation flow is calculated by coupling a mechanistic confinement approach with the ESSA model. Thus, the proposed engineering approach is used to model the main properties of one of the most common ammonium nitrate-based explosive used in mining and quarrying industries, including the complete axial flow solution.
{"title":"Modelling non-ideal detonations in commercial explosives","authors":"Paulo Couceiro, J. Miguel","doi":"10.4322/2176-1523.20222237","DOIUrl":"https://doi.org/10.4322/2176-1523.20222237","url":null,"abstract":"Highly non-ideal explosives usually react expressively below their ideal velocities of detonation. In these cases, dimensional effects and product heterogeneities become important to proper model their respective detonation state. Although Direct Numerical Simulation (DNS) techniques can provide a complete and exact solution for this problem, their actual computation cost are still not practical for industrial applications. In order to minimize these constrains, a simplified two-dimensional steady non-ideal detonation model for cylindrical stick explosives is presented. Based on an ellipsoidal shock shape approach (ESSA), the proposed model combines the quasi-one-dimensional theory for the axial flow solution with the unconfined sonic post-flow conditions at the edge of the explosive. Once calibrated, the model offers the possibility to predict the non-ideal detonation state for any charge diameter, resulting in a full mapping of the diameter-effect curve of the explosive. In addition, the effect of the inert confiner on the detonation flow is calculated by coupling a mechanistic confinement approach with the ESSA model. Thus, the proposed engineering approach is used to model the main properties of one of the most common ammonium nitrate-based explosive used in mining and quarrying industries, including the complete axial flow solution.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526396","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222645
L. C. Fontana, David Pascoal Sudaia, A.A.C. Recco, André Olah Neto, P. Borges, W. Guesser
Present paper sets out to investigate the role of N2/H2/Ar working gas in plasma nitriding of nodular cast iron. The proportion of N2/H2/Ar proved to be a relevant parameter in the growing kinetics control of the γ’-Fe4N e ε-Fe3N compound layers. X-ray diffraction and optical microscopy were used in order to characterize the compound layers. Results indicate that there are no generation of compound layers if the treatment is performed through plasma of pure N2. However, even small percentages (~10%) of auxiliary gases (H2/Ar), added to the working gas, are enough to generate compound layers as thick as 10μm (at 500 °C, and 3,0 h). In addition, it is possible to obtain γ’-Fe4N monophasic compound layer when the nitriding process is carried out in low proportion of nitrogen in the N2/H2/Ar working gas mixture.
{"title":"Cast iron plasma nitriding in N2 /H2 /Ar working gas: the role of auxiliary gases (H2 /Ar) in the growing kinetics of compound layers","authors":"L. C. Fontana, David Pascoal Sudaia, A.A.C. Recco, André Olah Neto, P. Borges, W. Guesser","doi":"10.4322/2176-1523.20222645","DOIUrl":"https://doi.org/10.4322/2176-1523.20222645","url":null,"abstract":"Present paper sets out to investigate the role of N2/H2/Ar working gas in plasma nitriding of nodular cast iron. The proportion of N2/H2/Ar proved to be a relevant parameter in the growing kinetics control of the γ’-Fe4N e ε-Fe3N compound layers. X-ray diffraction and optical microscopy were used in order to characterize the compound layers. Results indicate that there are no generation of compound layers if the treatment is performed through plasma of pure N2. However, even small percentages (~10%) of auxiliary gases (H2/Ar), added to the working gas, are enough to generate compound layers as thick as 10μm (at 500 °C, and 3,0 h). In addition, it is possible to obtain γ’-Fe4N monophasic compound layer when the nitriding process is carried out in low proportion of nitrogen in the N2/H2/Ar working gas mixture.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526676","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222734
L. A. Silva, A. C. Silva, Elenice Maria Schons Silva, Luany Beatriz Amanajás de Oliveira
Starches are depressant reagents used in mineral flotation in order to confer selectivity to the process. For this, they need to be previously gelatinized, with the alkaline method being the most used technique in the mineral industry. In Brazil, NaOH is used as alkali and the flour/NaOH ratio is a parameter analyzed in this process. Although they are important, studies on this topic are scarce in the literature. That said, the work consisted in determining the ideal flour/ NaOH ratio for the gelatinization of depressants based on corn, sorghum and millet and in proving the effectiveness of the process under optical microscopy with polarized light. Subsequently, flotation tests with niobium ore using corn, millet and sorghum flours and their respective mixtures as depressants were carried out and the results were compared with industrial corn starch. The results showed that the new proposed depressants used smaller amounts of NaOH to be gelatinized in relation to corn starch. The optical microscopy stage confirmed the disruption of Maltese crosses for all flours, indicating complete gelatinization. The best pyrochlore depressant was sorghum flour and the results showed statistical similarity with corn starch.
{"title":"Determinação da relação farinha/NaOH na gelatinização de depressores à luz da microscopia óptica e a sua influência nos testes de flotação mineral","authors":"L. A. Silva, A. C. Silva, Elenice Maria Schons Silva, Luany Beatriz Amanajás de Oliveira","doi":"10.4322/2176-1523.20222734","DOIUrl":"https://doi.org/10.4322/2176-1523.20222734","url":null,"abstract":"Starches are depressant reagents used in mineral flotation in order to confer selectivity to the process. For this, they need to be previously gelatinized, with the alkaline method being the most used technique in the mineral industry. In Brazil, NaOH is used as alkali and the flour/NaOH ratio is a parameter analyzed in this process. Although they are important, studies on this topic are scarce in the literature. That said, the work consisted in determining the ideal flour/ NaOH ratio for the gelatinization of depressants based on corn, sorghum and millet and in proving the effectiveness of the process under optical microscopy with polarized light. Subsequently, flotation tests with niobium ore using corn, millet and sorghum flours and their respective mixtures as depressants were carried out and the results were compared with industrial corn starch. The results showed that the new proposed depressants used smaller amounts of NaOH to be gelatinized in relation to corn starch. The optical microscopy stage confirmed the disruption of Maltese crosses for all flours, indicating complete gelatinization. The best pyrochlore depressant was sorghum flour and the results showed statistical similarity with corn starch.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526763","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222589
Matheus Vinícius Gregory Zimmermann, Gabriel Augusto Malvão Silva
{"title":"Avaliação de materiais utilizados em compósitos com estrutura sanduíche para aplicação em pranchas de surfe","authors":"Matheus Vinícius Gregory Zimmermann, Gabriel Augusto Malvão Silva","doi":"10.4322/2176-1523.20222589","DOIUrl":"https://doi.org/10.4322/2176-1523.20222589","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526157","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222565
B. Guimarães, L. E. Carvalho, C. A. A. Cairo
{"title":"Otimização da adesão interfacial do compósito fibra de carbono/epóxi utilizando tratamento superficial oxidativo","authors":"B. Guimarães, L. E. Carvalho, C. A. A. Cairo","doi":"10.4322/2176-1523.20222565","DOIUrl":"https://doi.org/10.4322/2176-1523.20222565","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526561","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222653
Francislaynne Lages Dias, Aline de Oliveira Ferreira, I. Oliveira, Aline Silva Magalhães, Dagoberto Brandão Santos
{"title":"Efeito da temperatura de recozimento intercrítico e do passe de encruamento na microestrutura e nas propriedades mecânicas de um aço médio manganês (0.09C-8Mn)","authors":"Francislaynne Lages Dias, Aline de Oliveira Ferreira, I. Oliveira, Aline Silva Magalhães, Dagoberto Brandão Santos","doi":"10.4322/2176-1523.20222653","DOIUrl":"https://doi.org/10.4322/2176-1523.20222653","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526687","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222620
J. Sertucha, J. Lacaze, A. Regordosa, U. Torre
Holding during 8 hours a melt prepared for casting SGI leads to fading of the spheroidizing treatment and thus to growth of compacted graphite instead of spheroidal graphite. Such a melt was cast in thermal analysis cups at 25-30 minutes interval without inoculation. It solidified first in the stable system and more and more in the metastable system. Accordingly, recalescence first increased as more of compacted graphite solidified, but then decreased when more and more of the solidification occurred in the metastable system. Comparison of the results of the present study with those of a previous similar series showed a higher peak recalescence while the number of compacted graphite cells and the graphite fraction were the same within experimental scattering. Furthermore, as the amount of spheroidizers was similar in both series, there is no clear reason for this difference in recalescence, which should be investigated further.
{"title":"Successive steps of growth of compacted graphite in cast irons","authors":"J. Sertucha, J. Lacaze, A. Regordosa, U. Torre","doi":"10.4322/2176-1523.20222620","DOIUrl":"https://doi.org/10.4322/2176-1523.20222620","url":null,"abstract":"Holding during 8 hours a melt prepared for casting SGI leads to fading of the spheroidizing treatment and thus to growth of compacted graphite instead of spheroidal graphite. Such a melt was cast in thermal analysis cups at 25-30 minutes interval without inoculation. It solidified first in the stable system and more and more in the metastable system. Accordingly, recalescence first increased as more of compacted graphite solidified, but then decreased when more and more of the solidification occurred in the metastable system. Comparison of the results of the present study with those of a previous similar series showed a higher peak recalescence while the number of compacted graphite cells and the graphite fraction were the same within experimental scattering. Furthermore, as the amount of spheroidizers was similar in both series, there is no clear reason for this difference in recalescence, which should be investigated further.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526971","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222681
F. Cardozo, C. Petter, N. Albuquerque
This study presents the application of the Monte Carlo method as a procedure of risk analysis in economic evaluation, covering, through the evaluation methodology presented, the stages of conceptual and pre-feasibility projects. In addition to the literature review, the methodology was applied to a cash flow prepared for an underground gold mine project in Brazil, exploited through the long hole mining method. Thus, deterministic evaluation methodologies were compared with the probabilistic output provided by the Monte Carlo method. The risk analysis made it possible to evaluate the impact of variations in the economic model’s input data: ore content, tonnage, ore price, OPEX (Operational Expenditure), CAPEX (Capital Expenditure), commissioning time, and mining recovery. In the example studied, the simulated scenarios indicated a 98.6% chance of the NPV (Net Present Value) being greater than zero and a mean NPV of $ M 261.186 versus $ M 287.513 from the deterministic cash flow evaluation. All these analyses are essential to evaluate the risks of failure, investments and economic and financial viability of a mining enterprise, being essential for planning and decision making in similar studies. probabilística Carlo. modelo econômico: investimentos fundamental decisão similares. Tornado Sensitivity Analysis.
{"title":"Monte Carlo simulation risk analysis for underground mining projects","authors":"F. Cardozo, C. Petter, N. Albuquerque","doi":"10.4322/2176-1523.20222681","DOIUrl":"https://doi.org/10.4322/2176-1523.20222681","url":null,"abstract":"This study presents the application of the Monte Carlo method as a procedure of risk analysis in economic evaluation, covering, through the evaluation methodology presented, the stages of conceptual and pre-feasibility projects. In addition to the literature review, the methodology was applied to a cash flow prepared for an underground gold mine project in Brazil, exploited through the long hole mining method. Thus, deterministic evaluation methodologies were compared with the probabilistic output provided by the Monte Carlo method. The risk analysis made it possible to evaluate the impact of variations in the economic model’s input data: ore content, tonnage, ore price, OPEX (Operational Expenditure), CAPEX (Capital Expenditure), commissioning time, and mining recovery. In the example studied, the simulated scenarios indicated a 98.6% chance of the NPV (Net Present Value) being greater than zero and a mean NPV of $ M 261.186 versus $ M 287.513 from the deterministic cash flow evaluation. All these analyses are essential to evaluate the risks of failure, investments and economic and financial viability of a mining enterprise, being essential for planning and decision making in similar studies. probabilística Carlo. modelo econômico: investimentos fundamental decisão similares. Tornado Sensitivity Analysis.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70526987","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}
Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222753
A. C. E. Silva
Steels are multiphase alloys with an increasingly complex constitution. This complexity of steel microstructures has been recognized since the birth of steel physical metallurgy. Non-metallic inclusions have also been very early recognized as relevant to the understanding of steel behavior. With the advances in precipitation hardening and grain size control, many precipitate phases gained importance in steel design. Around 1950-70 the term “second phases” was coined as an all-encompassing definition that would cover non-metallic inclusions as well as fine precipitates such as nitrides and carbonitrides even in steels that already had a multi-phase constitution. While this classification may be practical in some cases, we argue that it hinders the proper understanding of the origin and effects of particles in steel and unduly complicates the understanding of the phenomena in which they take part. In this work, we briefly review the origin of the second phase particle concept and discuss the critical properties of particles with respect to their influence on steel behavior. Through several examples, we propose that size and volume fraction are the main variables in evaluating how particles affect steels. While chemical composition is key to understanding the origin of the particles, we suggest that these variables are, together with interface properties, the most relevant to understand the effect of particles on steel behavior.
{"title":"Second phases in steel: a review of the concept, origin, and their relevance for properties","authors":"A. C. E. Silva","doi":"10.4322/2176-1523.20222753","DOIUrl":"https://doi.org/10.4322/2176-1523.20222753","url":null,"abstract":"Steels are multiphase alloys with an increasingly complex constitution. This complexity of steel microstructures has been recognized since the birth of steel physical metallurgy. Non-metallic inclusions have also been very early recognized as relevant to the understanding of steel behavior. With the advances in precipitation hardening and grain size control, many precipitate phases gained importance in steel design. Around 1950-70 the term “second phases” was coined as an all-encompassing definition that would cover non-metallic inclusions as well as fine precipitates such as nitrides and carbonitrides even in steels that already had a multi-phase constitution. While this classification may be practical in some cases, we argue that it hinders the proper understanding of the origin and effects of particles in steel and unduly complicates the understanding of the phenomena in which they take part. In this work, we briefly review the origin of the second phase particle concept and discuss the critical properties of particles with respect to their influence on steel behavior. Through several examples, we propose that size and volume fraction are the main variables in evaluating how particles affect steels. While chemical composition is key to understanding the origin of the particles, we suggest that these variables are, together with interface properties, the most relevant to understand the effect of particles on steel behavior.","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70527278","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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