O comportamento eletroquímico do aço-carbono 1005, do aço galvanizado e do zinco foi estudado em meios aerados de ácido sulfúrico 0,5 mol.L-1 (aço-carbono) e cloreto de sódio 0,01 mol.L-1 na ausência e presença do inibidor de corrosão benzotriazol (BTAH), a 25 ºC. Foram empregadas como técnicas ensaios gravimétricos, medidas de transitórios de potencial de circuito aberto, voltametria linear, espectroscopia de impedância eletroquímica (EIE), varredura com eletrodo vibratório (SVET), microscopia eletrônica de varredura (MEV), espectroscopia por dispersão de energia (EDS), espectroscopia eletrônica de raio X (XPS), espectroscopia Raman. O BTAH se mostrou inibidor para os três materiais metálicos nos meios estudados, comportando-se como inibidor misto. A sua ação inibidora decresce na ordem Zn>aço carbono>aço galvanizado em meio de cloreto de sódio. Para o aço-carbono em meio de ácido sulfúrico a adição de íons Cu(II) eleva a eficiência do BTAH, mas em tempos mais elevados de imersão há formação de cobre metálico que promove corrosão galvânica. Em meio de cloreto de sódio os filmes formados sobre aço e sobre zinco correspondem aos respectivos complexos Fe(III) e Fe(II) e de Zn(II) com BTAH. A ação sobre o zinco do BTAH, no caso do aço galvanizado reduz a eficiência na proteção catódica conferida pelo zinco ao aço. A eficiência inibidora sobre aço-carbono depende da composição da liga e da natureza das inclusões presentes no material. Estudos sobre a secção transversal do aço galvanizado em meio de cloreto de sódio mostraram que o BTAH inibe a oxidação do zinco, com formação do complexo, e a redução do oxigênio sobre o aço, com adsorção da molécula de BTAH. O filme formado sobre zinco, ensaiado separadamente, obedece à isoterma de Langmuir, com valores de energia livre padrão de adsorção que evidenciam a natureza química da adsorção, apontando para um complexo com BTAH. / The electrochemical behavior of carbon steel, galvanized steel and zinc has been studied in aerated 0.5 mol.L-1 sulfuric acid and 0.01 mol.L-1 sodium chloride solutions in the absence and presence of benzotriazole (BTAH) at 25ºC. Weight loss experiments, open circuit potential, transient measurements, linear voltammetry, electrochemical impedance spectroscopy (EIS), scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), canning vibrating electrode technique (SVET), X-ray photoelectron spectroscopy and Raman spectroscopy used as techniques. BTAH has shown inhibition for the three materials in the media studied and acted as a mixed inhibitor. Its inhibitive effect decreases in the sequence Zn>carbon steel>galvanized steel in chloride medium. In sulfuric medium the BTAH efficiency is improved with the presence of Cu(II) ions but this effect is suppressed at long times immersion when metallic copper is formed promoting galvanic corrosion. The films formed on zinc and carbon steel in chloride medium correspond, respectively to a Fe(II), Fe(III) mixed complex and to Zn(II) complex with BTAH. Studies on the cross section of galvanized steel (cut edge) have shown that the high effect of BTAH as inhibitor for zinc tends to decrease the efficiency of cathodic protection of this metal on carbon steel. For carbon steel in sulfuric medium the composition and the nature of inclusions have an important role on the inhibitor efficiency. On the cut edge the inhibitor promotes the formation of a zinc complex on this metal and it is adsorbed on carbon steel as a molecule inhibiting the oxygen reduction. The film formed on zinc when separately studied obeys to a Langmuir isotherm with standard adsorption free energy values denoting the presence of chemical adsorption as an indicative of the presence of a complex

Este trabalho apresenta um estudo do processo de cromatização de arames galvanizados da Linha de Galvanização 2 da Gerdau Riograndense através do entendimento das variáveis de processo que podem ser alteradas com o intuito de proporcionar uma resistência à oxidação branca maior do que a fornecida com os parâmetros de processo utilizados atualmente. Amostras de arames foram coletadas diretamente da linha de galvanização e submetidas a ensaios acelerados de corrosão em câmaras de umidade saturada (NBR 8095 e ISO 6270-2)16 e de névoa salina (NBR 8094 e ASTM B 117)15. Com base nos resultados obtidos destes ensaios são propostas alterações nas variáveis de processo, como por exemplo, tempo de imersão no tanque de cromatizante, avaliando o aumento ou não do poder protetivo. Os resultados obtidos até agora mostraram que as configurações operacionais da Linha de Galvanização 2 não oferecem uma condição para a formação de uma camada protetora eficiente. Espera-se com este trabalho justificar junto à Empresa a necessidade de alteração de parâmetros de processo para que se consiga obter significativo aumento no poder protetivo conferido pelo cromatizante ao arame galvanizado, e assim, ter condições de disponibilizar ao mercado um produto com qualidade superior no que tange a resistência à oxidação branca. / This work presents a study about the chromatization process for galvanized steel wires in the Galvanizing Line 2 of the Gerdau Riograndense through the understanding of variables of the process that can be modified to provide a superior white corrosion resistance than the one which is provided actually. Samples of wires were collected directly from the galvanizing line and submitted to accelerated corrosion tests in the saturated humidity chamber (NBR 8095 and ISO 6270-2)16 and the salt spray chamber (NBR 8094 and ASTM B 117)15. Based in the results from this tests changes in the process variables are proposed like immersion time in the chromatizating bath to evaluate the increase or decrease of the protective action. The results obtained so far showed that the operational configurations of the Galvanizing Line 2 do not offer a good condition to create an efficient protective layer on the wire. The expectation of this work is to justify to the company that changes in the parameters process are necessaries to get a significant increasing of the protective chromatizating action on the galvanized wire and this way to have conditions to offer to costumers a product with superior quality about white corrosion resistance.

Le travail présenté essaie de comprendre les mécanismes de l’action d’un inhibiteur de corrosion présent dans un revêtement hybride sous forme de pigments intercalés dans les hydroxydes double lamellaires (HDL) pour la protection de l’acier galvanisé. Trois étapes clés ont été choisies pour ce travail : (1) l’identification d’un inhibiteur de corrosion hydrosoluble pour l’acier galvanisé avec une compréhension de sa réactivité, (2) la détermination des facteurs et des mécanismes contrôlant la libération de l’inhibiteur à partir d’HDL et (3) la compréhension des mécanismes de protection dans un système modèle avec le revêtement hybride contrôlé par la libération de l’inhibiteur et la réactivité d’inhibiteur. MoO42- a montré la meilleure efficacité d'inhibition comparable à CrO42- dans des solutions alcalines et neutres. L’effet inhibiteur de MoO42- a été associé à la formation d’un film riche en Mo(V). L'effet de cet anion sur la dissolution de l'acier à bas carbone a été également vérifié pour exclure la possibilité d'un effet d'accélération des espèces choisies. Les tests de lixiviation ont montré que la libération de MoO42- à partir d’HDL a été contrôlée par la nature des ions échangés à partir du support par un mécanisme d'échange d'ions à un pH neutre et par la dissolution du cadre de la LDH à un pH alcalin. La présence de seulement Cl- conduit à moins de 40% de libération de MoO42- après 24 h d'immersion alors que les additions des carbonates ont abouti à libération de 100% après 1 h. Les tests d'immersion ont montré léger effet d'inhibition du système de revêtement dans Cl- et une augmentation dans CO32- en accords avec le niveau plus élevé de MoO42- libéré. / The current work was dedicated to the investigation of the fundamental mechanisms of the action of a layered double hydroxide (LDH) inhibitor hybrid coated systems for the corrosion protection of galvanized steel. The objective of the work was achieved by the realization of three milestones: (1) the identification of the effective water soluble inhibitor on Zn and steel substrates and the understanding the mechanisms of its action, (2) the revealing the factors and mechanisms controlling the release of the selected inhibitor from Zn2Al/-LDH hosts and (3) the understanding the mechanisms of coated system controlled by inhibitor release and its action. MoO42- showed the best inhibition efficiency comparable to CrO42- in alkaline and neutral solutions. The protective properties of MoO42- were assigned to the fast formation of Mo(V) film. The effect of MoO42- on the dissolution of low carbon steel was also verified to exclude the possible accelerating effect of chosen species. The leaching tests showed that MoO42- release from LDH was controlled by the nature of the exchanged ions from the media by ion-exchange mechanism at neutral pH and by the dissolution of the LDH framework at alkaline pH. The presence of only Cl- resulted in less than 40 % of MoO42- release after 24 hours of the immersion while the additions of the carbonates resulted in 100 % release after 1 hour. The immersion tests showed slight inhibiting effect of coated system in Cl and high in CO32- medias coherent with higher level of MoO¬42- released. The ways to control the inhibitor release and hence, the inhibition performance of coated systems were discussed in the vein of environment composition.

O uso de chapas finas de aço, revestidas ou não, tem sido crescente nos últimos anos, principalmente aquelas que tem revestimento à base de zinco. Isto ocorre tanto na indústria automobilística e mecânica como na construção civil, que geralmente fabricam suas peças e estruturas utilizando um procedimento de soldagem. O objetivo deste trabalho é estabelecer procedimentos de soldagem à arco elétrico com proteção gasosa - GMAW - com transferência por curto circuito, para elementos de chapa fina de aço carbono não revestido e aço zincado, de modo a se obter junções de qualidade aceitável e diminuição das distorções decorrentes dos ciclos térmicos presentes durante a soldagem e, consequentemente a redução das tensões residuais. Em termos de qualidade da solda, propões-se uma combinação de consumíveis disponíveis no mercado, de modo a reduzir os defeitos como: porosidade, respingos, trincas e perda de revestimento. No caso das chapas finas de aço zincado, a melhor combinação de consumíveis encontrada foi: arame com baixo teor de desoxidantes, ER70S-3, e como gás de proteção a mistura 8% CO2 + 92% Ar. Quanto à redução e controle das distorções, três técnicas são utilizadas. A técnica que utiliza em escoadouro dinâmico de calor, formado por um jato de gás refrigerador aplicado logo após o arco de solda durante a soldagem, apresentou maior eficiência na redução das distorções, provenientes do ciclo térmico. / The thin sheet steels, coated or not, has been widely used nowadays, mainly the hot dip galvanized steel sheets. It\'s observed as in the mechanic and automobilist industry as in the civil construction that in manufacturing of pieces and structures employ welding procedures. The aim of this work is to establish procedures to gas metal are welding with short circuit transfer of thin sheet steel elements, not coated and zinc-coated steel, in order to get junctions of acceptance quality and reduction of welding stress and distortion. This distortion arise of the thermal cycles that occur during the welding. In terms of the weld quality is defined the best consumables combination available in the market, in such a way to reduce the weld defects like porosities, spatters, cracks and loss of covering. To galvanized steel sheets, the combination: wire ER70S-3 and mixture 8%CO2 + 92% Ar showed the best performance. Three techniques were employed for control and reduce the welding distortion. One that using a spot heat sink following the arc, in this case the cooling jet, was more efficient that others techniques.

Mechanically stabilized earth (MSE) walls are a more advanced form of a retaining wall, often larger and able to hold back more backfill. This is achieved by reinforcing strips or meshes (most often galvanized steel) placed into the soil, which are held in place by friction. The strips mechanically stabilize the earth while undergoing tension. The wall is covered with concrete medallions that connect to the reinforcements. The medallions have only a secondary structural role in holding up the wall but provide cover that protects the soil from washing away. MSE walls are structures expected to have very long service lives (e.g. 100 years). Confirmation is needed that such durability can be achieved, especially to show that the progression of corrosion of the reinforcement is slow enough. Ten MSE walls around Florida were instrumented (electrical connections were made through the concrete covers to the buried elements) between 1996- 1998 and used to survey corrosion rates of galvanized strip or mesh soil reinforcements. Initial estimates of corrosion-related durability were obtained at that time, indicating a good prognosis for long term durability. The objective of the research in this thesis was to obtain additional indications of the durability of reinforcements in MSE walls in Florida so as to perform a more reliable projection of future performance. Corrosion behavior was measured at the same locations as the initial survey by electrochemical nondestructive tests and by destructive tests. The nondestructive testing consisted of half-cell potentials, polarization resistance measurements, and electrochemical impedance spectroscopy. Corrosion rates reported in this thesis are based upon polarization resistance measurements. The destructive testing consisted of soil extraction and hardware extraction. Hardware extraction enabled independent verification of estimates of electrochemical corrosion rate. Analysis of extracted soil verified that soil composition was within construction specifications. The data from the current survey were also used to further improve prediction of corrosion. The present series of evaluations confirm that the structures are performing as desired based upon the updated model projection of future corrosion.

In recent years, the automotive industry has turned to press hardened steels (PHS) to improve passenger safety while enabling vehicle weight reduction. To form the complex shapes required for this purpose, they are often direct hot press formed. It is possible to provide corrosion resistance to these parts by galvanizing the PHS sheets prior to direct hot press forming (DHPF). However, the austenitization of the galvanized steel causes the Zn-based coating to transform into two intermetallic phases. These are iron-rich α-Fe(Zn) and zinc-rich Г-Fe3Zn10. The Г-Fe3Zn10 is liquid during traditional DHPF, and the applied stress can result in liquid metal embrittlement (LME). Recently, two new grades of PHS have been developed, which allow for DHPF at 600-700°C, below the Fe-Zn peritectic temperature at 782°C, thus avoiding LME. These prototype PHS grades are designated 2%Mn (0.2C-2Mn-0.25Si-0.005B (wt%)) and 2.5%Mn (0.2C-2.5Mn-0.25Si-0.005B (wt%)). The objective of this work is to determine the effect of DHPF on the ability of a Zn-based coating to provide robust cathodic protection to the two prototype PHS. Galvanized panels of both the 2%Mn and 2.5%Mn steel were DHPF with a U-shape die at 700°C. The surface and cross-section of the coating were examined to determine the effects of DHPF on the coating surface. Die friction during DHPF resulted in die wiping on the wall of the part, leading to removal of surface Г-Fe3Zn10. In cross-section, coating cracks were present at the wall and corner of the U-shape part due to the deformation during DHPF. Potentiodynamic polarization scans were used to determine the corrosion potential of the coating, and this was used to calculate the driving force for cathodic protection using the difference in corrosion potential between the coating phases and the substrate. It was found that only Γ-Fe3Zn10 provided robust cathodic protection to both steel substrates, and the driving force for cathodic protection was lower for the coated DHPF 2.5%Mn steel. Galvanostatic scans were used to evaluate dissolution kinetics of coating phases. Robust cathodic protection was provided by the galvanized coating for austenitization times of 30 - 120 s for the 2%Mn substrate and 30 - 60 s for the 2.5%Mn substrate. The duration that robust cathodic protection was provided was shortest at the wall of the U-shape part. This result was attributed to die wiping caused by DHPF, where the surface is smoothed by die friction. When there is less Г-Fe3Zn10 in the coating, such as at longer austenization times, surface Г-Fe3Zn10 was removed and an increased amount of α-Fe(Zn) is exposed, which does not provide robust cathodic protection. In addition, coating cracks form along α-Fe(Zn) grain boundaries after austenitization for 180 s on all examined regions of the U-shape part, allowing a greater surface area of the coating exposed to electrolyte, further increasing dissolution of the coating. / Thesis / Master of Applied Science (MASc)

O processo de soldagem por resistência de chapas galvanizadas automotivas é parte indispensável na concepção de uma carroceria de automóvel. Utilizado na união das chapas metálicas que formam um veículo, a grande importância deste processo deve-se basicamente ao fato de não agregar peso à carroceria, ter um desempenho satisfatório em relação à qualidade e produtividade nas linhas de montagem e ainda não onerar o custo final do produto, visto que seu custo de operação pode ser considerado baixo de modo geral. As variáveis específicas deste processo demandam atenção permanente quanto aos parâmetros dos equipamentos, a limpeza e a manutenção, a refrigeração dos eletrodos, a dressagem e a eliminação da camada de latão formada na superfície de contato entre o eletrodo e a chapa. A durabilidade e o desgaste do eletrodo estão ligados basicamente a estes cuidados, podendo ainda gerar ganhos em produtividade e qualidade do ponto além de reduzir o nível de problemas durante e após a soldagem da chapa. Durante a realização deste trabalho, procurou-se avaliar o comportamento do eletrodo fabricado através da liga Cu-Zr, o desgaste do eletrodo em relação ao número de pontos soldados, sua relação com a dureza e variação de temperatura durante o processo, os cuidados que podem retardar o desgaste e a microestrutura do material ao longo do número de pontos e do desgaste deste eletrodo. / The resistance welding process of automotive galvanized steel is an indispensable part in the design of a body car. Used in the union of the metal plates that form a vehicle, the great importance of this process is basically due to the fact not add weight to the body, have a satisfactory performance in relation to quality and productivity in assembly lines and still does not burden the final cost the product, the operating cost can be considered low in general. The specific variables this process require constant attention regarding the parameters of the equipment, cleaning and maintenance, cooling the electrodes, the dressing and the elimination of the brass layer formed on the contact surface between the electrode and the plate. The durability and the electrode wear are basically related to such care, and may generate gains in productivity and quality of point and reduce the level of problems during and after welding the plate. During this work, we tried to evaluate the electrode manufactured by Cu-Zr alloy, the electrode wear in relation to the number of welding points, their relationship with the hardness and temperature variation during the process, the care can slow the wear and the microstructure of the material during the number of welding points and the wear of this electrode.

Abstract Prepainted steel is a new material developed after the year of 1960. It owns mainly advantages accompanied with corrosion resistance, long-life using, beautiful color and shape, easy utilization, and also keep the original strength of the steel. All these characteristics make it appropriate to be used on the wall, roof, and decoration of gym or any big construction and buildings. It can also be seen in the field of vehicles, many electrical appliances, computer shells, etc. Prepainted steel is the downstream product of steel enterprises. It comes manly from Galvanized steel coils, and a little portion of it from cold-rolled steel coils. There are now seven production companies in Taiwan at the annual production of 1.17 million tons. According to statistics, the local consumption of last year is 310,000 tons. It is fortunate that Mainland China has a mass need for it during these years. In 2002, Mainland china imported 1.02 million tons, and in 2003, 1.54 million tons. We need huge export to digest our production. My study case is an medium enterprise with the annual production 300,000 tons of prepainted steel, and without the production line of Galvanized steel with which prepainted steel can be done. This study mainly discusses how an enterprise construct its own competitive advantage and strategy through the outside environment analysis and management ability, then make the best choice of stragtegy which is appropriate to its business model before evaluating the strategy efficiency by theory. The first chapter is about its background and motive of the study, and contents and limits of the study are also included. The second chapter, from the theory basis of documents, try to understand the definition and relative meaning of following issues: vertical integration, strategic alliance, resources leveling and value chains¡Ketc. The third chapter of this study is about the marketing supply and demand situation of prepainted steel local and abroad, and it talks about on what kind of location that prepainted steel enterprise stands. This chapter also goes further introducing these important enterprises in Taiwan which earns prepainted steel, and make an analysis on enterprise environment and five forces analysis. The fourth chapter has an introduction of this study case and its cooperators and opponents. Moreover, a SWOT analysis of this study case is offered. Futher, there has a discussion on its strategy on competitive advantage ¡V strategic alliance, resources leveling,, value chains, vertical integration, business field¡Ketc. And a proof on the basic of the strategy and an evaluation on these strategic efficiency are made. At last, there will be a deep thinking on fast-changing environment and future strategies. We hope the ending can be used for the reference of this enterprise.

Made available in DSpace on 2016-12-08T17:19:21Z (GMT). No. of bitstreams: 1 Ana Paula Domingos Cardoso.pdf: 8690501 bytes, checksum: b120ead6518f05e5ff1cb9d530fa6bfe (MD5) Previous issue date: 2013-12-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present work aims to develop and characterize galvanized steels with chemical post-treatment application, which provides to the metal forming improvement properties. The main reason for this development is related with the fact that the most of zinc coatings problems are related with their sensitivity for abrasion wear during forming process. In view of these difficulties, related with coating steel forming, the Arcelormittal group has been developing Pos-Treatment solutions known as NIT (New Treatment Innorganic) and Pre-phosphate with the main function to promote the improvement of forming properties in deep stamping process through the lubricating properties. The propose solutions was applied over the standard steels known as IF, and galvanized with GI and GA zinc coatings. The forming improvement were evaluated through wear tests by plane friction and pin on disc tribometer, with aim to determine the friction coefficient behaviour for these materials in front of contacts pressure (MPa) application and distance (m). In addition, cracking potential analysis was done through Erichsen and weight loss methods to evaluate the powdering failure possibility. The post-treatment microstructure was evaluated through MEV and FEG-EDS analysis. As a complement study was simulated remobility tests to reproduce one step of the automotive process that can be negative influenced by post treatment application waste on the strip after forming and was evaluated the material corrosion potential in humidity tests cycles / O presente trabalho tem o objetivo de desenvolver e caracterizar aços galvanizados com aplicação de pós-tratamento químico, que visam proporcionar ao metal melhoria de conformabilidade. A justificativa principal deste estudo esta no fato de que o principal problema de revestimentos à base de zinco vêm a ser a sua sensibilidade ao processo de desgaste por abrasão, podendo danificar tanto a peça revestida, como as ferramentas das prensas de estampagem, principalmente no processamento de peças críticas voltados para aplicações da indústria automotiva. Diante destas dificuldades, o grupo ArcelorMittal tem desenvolvido a aplicação de soluções de pós-tratamento do tipo NIT (New Innorganic Treatment) e pré-fosfato , com a função de promover ao aço galvanizado, melhoria de conformabilidade e , através da propriedade de lubrificação, durante processos de estampagem de peças de alta criticidade. As soluções propostas foram aplicadas sobre os aços convencionais do tipo IF, galvanizados com revestimento base Zn denominados GI e GA. Os ganhos de conformação foram avaliados por ensaios de desgaste realizados em tribômetros de fricção planar e pino sobre disco, a fim de avaliar o comportamento do coeficiente de atrito destes materiais diante da aplicação de determinadas pressões de contato (MPa) e distância percorrida (m). Além disto, foram realizados ensaios de avaliação de potencial de fratura do material através de testes em prensa de embutimento Erichsen e Perda de Massa, método este que visa avaliar a possibilidade de ocorrência de fragilizações por Powdering. Com intuito de conhecer a microestrutura dos filmes de póstratamento depositados sobre o aço revestido foram realizadas análises metalográficas via MEV e FEG-EDS. Como complemento ao trabalho foram realizados ensaios de remobilidade dos filmes aplicados, simulações de uma das etapas de processos da indústria automotiva que podem vir a sofrer influência do pós-tratamento após estampagem do material e avaliação do potencial de corrosão em ciclos de câmara úmida.

Made available in DSpace on 2016-12-08T17:19:24Z (GMT). No. of bitstreams: 1 Resumo - Alessandro.pdf: 35986 bytes, checksum: 64527c70f5220aac3e4860e883de96f7 (MD5) Previous issue date: 2014-08-08 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Carbon steel is among the most widely used materials in manufacturing metallic structures in the world, due to its low cost and good physical and mechanical properties. However, steel is the metal that suffers the greatest corrosive impact among building materials. Carbon steel corrosion is one of the biggest factors of structural degradation in the world. One of the applications for carbon steel is manufacturing bus bodies, whereas steel is used in making the frame and body components. Steel has always attracted interest in its use, but this material has always been susceptible to corrosive degradation compromising its properties. In many studies, researchers have presented alternatives to slow down the corrosion process and thus extend the life of metal components. The purpose of this work has been to study the corrosion of unpainted and painting galvanized steel plates, similar to components used in bus bodies, thus seeking to analyze the influence of painting on the corrosion resistance in galvanized steel. The test specimens were prepared using the 1020 steel ZAR230 specimens in the Albrecht Equipamentos Industriais Company from specimens donated by ArcelorMittal Vega do Sul. The specimens were prepared and painted with galvanic corrosion primer paint at the Gabivel Honda dealership purchased from the WEG tintas Company. The specimens were cleaned and sorted into three types, without painting, one coat of paint, and two coats of paint. The specimens were then weighed and measured, and the coats of paint were analyzed for thickness and adhesion. Then the specimens were placed in a laboratory machine donated by Schultz S / A. They salt sprayed for accelerated testing and cyclic corrosion and subjected to testing for 480 hours. We also conducted accelerated corrosion tests by immersion in saline solution for 1032 hours. Throughout the tests, the specimens were visually examined and upon completion these specimens underwent cleaning and weighing, for visual analysis and mass loss. The corrosion in the specimens caused corrosive pitting and corrosive scaling. The painted specimens displayed a higher corrosion resistance compared to unpainted specimens. The red oxidation and mass loss were higher in unpainted specimens. / Dentre os materiais mais utilizados na confecção de estruturas pelo mundo, o aço carbono se destaca pelo seu baixo custo e boas propriedades físicas e mecânicas. Contudo, o aço é o metal que mais sofre com a corrosão dentre os materiais de construção. A corrosão do aço carbono é um dos maiores fatores de degradação das estruturas no mundo. Uma das aplicações do aço carbono é na fabricação de carrocerias de ônibus, onde o aço é utilizado na confecção da estrutura e dos componentes da carroceria. O aço sempre despertou interesse em sua utilização, porém este material sempre foi susceptível a degradação pela corrosão o que acaba por comprometer suas propriedades. Em muitos trabalhos, os pesquisadores vêm apresentando alternativas para retardar o processo corrosivo e assim prolongar a vida útil de componentes metálicos. O presente trabalho teve por objetivo estudar a corrosão de chapas de aço galvanizado sem pintura e com pintura anticorrosiva, similares aos componentes utilizados em carrocerias de ônibus, buscando assim analisar a influência da pintura na resistência à corrosão do aço galvanizado. Os corpos de prova foram confeccionados na empresa Albrecht Equipamentos Industriais, a partir de amostras doadas pela ArcelorMittal Vega do Sul, sendo estas amostras de aço 1020 tipo ZAR230. Os corpos de prova foram preparados e pintados na Concessionária Honda Gabivel com a tinta primer anticorrosiva galvânica adquirida na empresa WEG tintas. As amostras foram limpas e separadas em três tipos, sem pintura, com uma camada de pintura e com duas camadas de pintura. Os corpos de prova foram então pesados e dimensionados, e suas camadas de pintura analisadas quanto à espessura e aderência. Em seguida as amostras foram posicionadas em máquina de ensaio acelerado e cíclico de corrosão acelerada por névoa salina, no laboratório cedido pela Schultz S/A, e submetidos ao ensaio por 480 horas. Foram realizados ainda, ensaios acelerados de corrosão por imersão em solução salina por 1032 horas. Ao longo dos ensaios, os corpos de prova foram analisados visualmente e após a finalização destes foram submetidos à limpeza e pesagem, para análise visual e de perda de massa. A corrosão presente nas amostras foi do tipo corrosão por pite e corrosão por placas. As amostras, com pintura, apresentaram uma maior resistência à corrosão em relação ás amostras sem pintura. A oxidação vermelha e a perda de massa foram maiores nos corpos de prova sem pintura.