Pub Date : 2022-01-01DOI: 10.4322/2176-1523.20222511
Luan Mayk Tôrres Costa, Gudson Nicolau de Melo, N. A. Castro, A. Buschinelli
This work shows the microstructural characterization of API-5L X65 and X70 steels manufactured by the TMCP process. Images are obtained by optical microscopy (OM), scanning electron microscopy (FEG-SEM) and atomic force microscopy (AFM). Besides, the EBSD technique pointed out that both samples are presenting a refined quasi-polygonal ferrite matrix with eutectoid aggregates in the contours and vertices of ferritic grains. Moreover, a grain size of 8.4 μm is estimated for X70 and 10.6 μm for X65 steel. In the AFM images, eutectoid aggregates displayed higher relief concerning the ferrite matrix, and these microconstituents’ higher hardness causes them. This behavior is in agreement with the results of the Vickers Hardness test. EBSD showed that the quantity of microphases in the X65 is slightly higher than in the X70. However, the X70 steel presented higher high and low angle lengths due to the greater refinement and stronger cooling rates applied during processing. The Vickers test showed that the ferrite hardness is similar for both steels. This same behavior is verified for the Vickers test in eutectoid aggregates. It indicates that the higher strength of X70 sample is mainly a consequence of the finer microstructure.
{"title":"Microstructural characterization of API 5L X65 and X70 steels manufactured by TMCP process","authors":"Luan Mayk Tôrres Costa, Gudson Nicolau de Melo, N. A. Castro, A. Buschinelli","doi":"10.4322/2176-1523.20222511","DOIUrl":"https://doi.org/10.4322/2176-1523.20222511","url":null,"abstract":"This work shows the microstructural characterization of API-5L X65 and X70 steels manufactured by the TMCP process. Images are obtained by optical microscopy (OM), scanning electron microscopy (FEG-SEM) and atomic force microscopy (AFM). Besides, the EBSD technique pointed out that both samples are presenting a refined quasi-polygonal ferrite matrix with eutectoid aggregates in the contours and vertices of ferritic grains. Moreover, a grain size of 8.4 μm is estimated for X70 and 10.6 μm for X65 steel. In the AFM images, eutectoid aggregates displayed higher relief concerning the ferrite matrix, and these microconstituents’ higher hardness causes them. This behavior is in agreement with the results of the Vickers Hardness test. EBSD showed that the quantity of microphases in the X65 is slightly higher than in the X70. However, the X70 steel presented higher high and low angle lengths due to the greater refinement and stronger cooling rates applied during processing. The Vickers test showed that the ferrite hardness is similar for both steels. This same behavior is verified for the Vickers test in eutectoid aggregates. It indicates that the higher strength of X70 sample is mainly a consequence of the finer microstructure.","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":"70526267","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: 10.4322/2176-1523.20222603
Luiz Eloi Vieira, L. H. Meyer, A. Teixeira, João Batista Rodrigues Neto, António Pedro Oliveira
{"title":"Caracterização química, mecânica, elétrica e microestrutural de resíduo de para-raios da região de Blumenau","authors":"Luiz Eloi Vieira, L. H. Meyer, A. Teixeira, João Batista Rodrigues Neto, António Pedro Oliveira","doi":"10.4322/2176-1523.20222603","DOIUrl":"https://doi.org/10.4322/2176-1523.20222603","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":"70526288","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: 10.4322/2176-1523.20222642
A. P. Tschiptschin, W. Guesser
In this paper, observations are made on the faceted crystallographic lateral growth structure of graphite flakes in a high Si GG20 cast iron. A 3.82 wt.% Si, 3.25% wt.%C slightly hypereutectic cast iron with large type C graphite flakes embedded in a ferrite + spheroidized pearlite matrix failed catastrophically. Fracture is propagated by debonding the graphite flakes from the metallic matrix, exposing the graphite flakes’ lateral surfaces on the fracture surface. Flake morphology and substructure were observed using scanning electron microscopy (SEM). Very thin and flexible triangular layers, nucleating on a “hexagonal rosette” center point, suggest a growth mechanism involving the incorporation of new carbon add-atoms. Epitaxial precipitation of secondary graphite during solid-state transformation shows a preferred growth habit in the a-direction, producing 2-D sheets of graphene to which carbon atoms can easily attach. Furthermore, the spiral growth of individual sheets, contributing to the thickening of the flake in the c-direction, could be inferred. The results are discussed, considering that graphite crystalline defects may play a decisive role in the spiral growth mechanism and the thickening of the graphite flake during solid-state secondary graphite precipitation.
{"title":"On the growth of graphite lamellae in a high Si GG20 cast iron","authors":"A. P. Tschiptschin, W. Guesser","doi":"10.4322/2176-1523.20222642","DOIUrl":"https://doi.org/10.4322/2176-1523.20222642","url":null,"abstract":"In this paper, observations are made on the faceted crystallographic lateral growth structure of graphite flakes in a high Si GG20 cast iron. A 3.82 wt.% Si, 3.25% wt.%C slightly hypereutectic cast iron with large type C graphite flakes embedded in a ferrite + spheroidized pearlite matrix failed catastrophically. Fracture is propagated by debonding the graphite flakes from the metallic matrix, exposing the graphite flakes’ lateral surfaces on the fracture surface. Flake morphology and substructure were observed using scanning electron microscopy (SEM). Very thin and flexible triangular layers, nucleating on a “hexagonal rosette” center point, suggest a growth mechanism involving the incorporation of new carbon add-atoms. Epitaxial precipitation of secondary graphite during solid-state transformation shows a preferred growth habit in the a-direction, producing 2-D sheets of graphene to which carbon atoms can easily attach. Furthermore, the spiral growth of individual sheets, contributing to the thickening of the flake in the c-direction, could be inferred. The results are discussed, considering that graphite crystalline defects may play a decisive role in the spiral growth mechanism and the thickening of the graphite flake during solid-state secondary graphite precipitation.","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":"70526639","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: 10.4322/2176-1523.20222594
Hugo Kamigashima Kohmann, Anna Luiza Macedo Silva
Ventilation in underground mining is paramount for a good mine operation. Inadequate or insufficient ventilation compromises workers’ health and safety, especially in coal mining that normally must deal with flammable gases and coal dust that can cause explosions. This paper aims to analyse the current ventilation system of an underground coal mine in southern Brazil by measuring the air velocity, determining the airflow in its airways, and simulating the mine ventilation system using a ventilation software. A visit was made to the coal mine to carry out the measurements and others essential characteristics of the mine to construct the model. The analysis of the results of the measured and simulated parameters allows it to be possible to use the model and adopt the proposed methodology with satisfactory accuracy. It is also concluded that the company meets the requirements of regulatory standards due to the periodic monitoring and because they provide a higher airflow than necessary. Nevertheless, there could be benefits with a ventilation model so that the ventilation could be optimized according to the mine’s evolution. However, for this, more air velocities sampling points are advisable, as well as the determination of the head loss between branches.
{"title":"Análise do sistema de ventilação de uma carbonífera brasileira","authors":"Hugo Kamigashima Kohmann, Anna Luiza Macedo Silva","doi":"10.4322/2176-1523.20222594","DOIUrl":"https://doi.org/10.4322/2176-1523.20222594","url":null,"abstract":"Ventilation in underground mining is paramount for a good mine operation. Inadequate or insufficient ventilation compromises workers’ health and safety, especially in coal mining that normally must deal with flammable gases and coal dust that can cause explosions. This paper aims to analyse the current ventilation system of an underground coal mine in southern Brazil by measuring the air velocity, determining the airflow in its airways, and simulating the mine ventilation system using a ventilation software. A visit was made to the coal mine to carry out the measurements and others essential characteristics of the mine to construct the model. The analysis of the results of the measured and simulated parameters allows it to be possible to use the model and adopt the proposed methodology with satisfactory accuracy. It is also concluded that the company meets the requirements of regulatory standards due to the periodic monitoring and because they provide a higher airflow than necessary. Nevertheless, there could be benefits with a ventilation model so that the ventilation could be optimized according to the mine’s evolution. However, for this, more air velocities sampling points are advisable, as well as the determination of the head loss between branches.","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":"70526211","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 : 2021-01-01DOI: 10.4322/2176-1523.20211801
Luiz Carlos Pereira, A. Reguly
{"title":"Telmo Roberto Strohaecker (1955-2016)","authors":"Luiz Carlos Pereira, A. Reguly","doi":"10.4322/2176-1523.20211801","DOIUrl":"https://doi.org/10.4322/2176-1523.20211801","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70523855","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 : 2021-01-01DOI: 10.4322/2176-1523.20212143
G. Costa, A. Moehlecke, I. Zanesco
{"title":"Influência do tipo de dopante do substrato em células solares bifaciais finas","authors":"G. Costa, A. Moehlecke, I. Zanesco","doi":"10.4322/2176-1523.20212143","DOIUrl":"https://doi.org/10.4322/2176-1523.20212143","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70524286","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 : 2021-01-01DOI: 10.4322/2176-1523.20212398
Reinaldo Lopes Ferreira, Cristina Godoy, E. Vasconcellos, Fernando Fernández
{"title":"Consórcios e suas barreiras no desenvolvimento de projetos P&D de tecnologias pré-competitivas: modelo conceitual e aplicação","authors":"Reinaldo Lopes Ferreira, Cristina Godoy, E. Vasconcellos, Fernando Fernández","doi":"10.4322/2176-1523.20212398","DOIUrl":"https://doi.org/10.4322/2176-1523.20212398","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70525147","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 : 2021-01-01DOI: 10.4322/2176-1523.20212402
Edson Fouad Beck, Paulo de Jesus Aniceto, Noé Cheung, C. Santos, Felipe Bertelli
{"title":"Modelagem numérica da transferência de calor do processo de lingotamento contínuo de tarugo oco de cobre em uma planta industrial","authors":"Edson Fouad Beck, Paulo de Jesus Aniceto, Noé Cheung, C. Santos, Felipe Bertelli","doi":"10.4322/2176-1523.20212402","DOIUrl":"https://doi.org/10.4322/2176-1523.20212402","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70525168","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 : 2021-01-01DOI: 10.4322/2176-1523.20212373
J. Alencar, Gabriellen da Silva Xavier do Carmo, Natállia Luiza Antunes Silva, Nathália Duarte Bastos, Pedro Silva Figueiredo
{"title":"Avaliação da influência da tipologia do minério em testes de sticking","authors":"J. Alencar, Gabriellen da Silva Xavier do Carmo, Natállia Luiza Antunes Silva, Nathália Duarte Bastos, Pedro Silva Figueiredo","doi":"10.4322/2176-1523.20212373","DOIUrl":"https://doi.org/10.4322/2176-1523.20212373","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70525529","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 : 2021-01-01DOI: 10.4322/2176-1523.20212442
F. D. Ramos, Josué de Oliveira Bairros, M. C. Moscoso
{"title":"Deep cryogenic treatment in AISI D2 tool steel punches to enhance tool life","authors":"F. D. Ramos, Josué de Oliveira Bairros, M. C. Moscoso","doi":"10.4322/2176-1523.20212442","DOIUrl":"https://doi.org/10.4322/2176-1523.20212442","url":null,"abstract":"","PeriodicalId":53327,"journal":{"name":"Tecnologia em Metalurgia Materiais e Mineracao","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70525681","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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