Narrow gaps in overlapping structural steel surfaces are problematic when being hot-dip galvanized due to the potential for trapped cleaning solutions between the surfaces. A seal-weld is often used to prevent the cleaning solutions from penetrating this gap. However, these welds are not necessary used for strength, and add fabrication costs because of the additional weld. The purpose of this research is to provide alternatives, which fall under two major categories, to the seal-weld fabrication process. The first one was motivated by the steel fabrication industry and uses a commercial silicone caulk to seal the narrow gap instead of a seal-weld. The second was motivated by the galvanizing industry and increases the narrow gap to a minimum of 3/32 in. to allow free flowing of the liquids including viscous molten zinc. 45 specimens in six different overlapping configurations were tested. Three experimental tasks were performed as part of this research: two different types of silicone caulks were used to partially substitute the seal-weld to prevent fluid penetration; an accelerated corrosion test was performed to determine the long-term corrosion resistance of each configuration; and a coating layer evaluation was performed to investigate the bond of the metallurgical layer between the steel and the coating. Results indicate that silicone only partially prevented the penetration of the cleaning solutions into the gap but performed poorly when fully galvanized. Also, the accelerated corrosion and coating investigations indicated that the suggested caulks and the 3/32 in. gap were not as efficient as the seal-weld solution. / Master of Science

Along with science and technology gradually make progress, there is no distance between country. WTO world commerce cloggy eliminate, have no frontier's confine to make product and service that almost be obvious everywhere in the world. Under economic liberalization and internationalize affection, make enterprise management no longer confine to one area or single country. Economic globalization impact everywhere in the world. Iron and steel industry can¡¦t also avoid meeting severely impact and change. In 2002, because global economies gradually change better, lead to international steel market demand to grow up quickly. It is fourth season to reach the best. Price appears take on upspring, too. Due to every important manufacturer rob to buy materical each other in the world, appear steel materical demand to exceed supply. At the end of the year 2003, America, European union, mainland China cancel import restriction successively. At the beginning of the year 2004, price of freight, iron ore, coalmine, scrap steel (Steel ingredient) increases largely at the same time. Many countries ensure steel requirement materials at home, so steel importation tariff transfer fall successively. It makes strict confine measure gradually change to loose. Hot Rolled Galvanized Steel Sheet requires mean consumption to grows up 4.4% near five years in the world. Price also rise along with the price of Hot-Rolled Steel Coil is on raise at the same time. Steel market changes quickly like electronic product¡¦s life. Steel industry face structure change and reform management. In the world, all steel industry is toward competition and cooperative style. Industry internationalize brings manufacture and sales mode's changed. Industry protection policy already do not exist. With environment changed quickly, enterprise do the best increase management performance. It just be able to abidingly run and develop. The study chiefly use questionaire as interview style to get information and organize theoretical document to review and research. Let us know Hot Rolled Galvanized Steel Sheet and Prepainted Hot-Dip Zinc Coated Steel Sheet company how to develop in the world now. It is as Yiehphui company for example, explore Hot Rolled Galvanized Steel Sheet and Prepainted Hot-Dip Zinc Coated Steel Sheet industry how to take advantage of limited source and face industry environmental change to upgrade management technique. By industry internationalization working principles, make enterprise management risk asunders and create industry competition advantage. It becomes industry developmental reference. The study shows some conclusions as follows: 1. Materials source need stability and multiplication. It avoid confining provider but have no method to acquire advantaged negotiate. 2. International steel area integrated tendency have already formed. Major company become bigger and bigger can not avoid. Individual company should cooperation or tactic federation at home with same industry company, form area economy magnitude and debases competition pressure. 3. Push and import TPM management system and TSM work safe management system to healthy company operate constitution and attract elitist. 4. Global market runs for springboard as strengthen developmental technology, develop high affixation value product and new product use domain. It aggravates brand impression and difference product to used for seize more market area and market benefit.

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Na busca contínua de atender as exigências de um mercado cada vez mais competitivo, as empresas devem buscar diminuir todas as suas perdas em seus processos produtivos, reduzindo custos e ganhando margem em seus produtos. Este trabalho teve como objetivo investigar os fenômenos presentes na ocorrência de quebras dos produtos derivados do aço SAE 1057B trefilado e galvanizado utilizado em culturas aéreas. O estudo utilizou bibliografia documental, pesquisa de laboratório e uma amostra composta por trinta e seis relatórios de análises sobre o desempenho do produto intermediário trefilado, ou do produto final galvanizado. Os dados referem-se à eventos de falhas do produto em quaisquer etapas do processo produtivo e mesmo de aplicação em campo. Juntamente com ensaios efetuados especificamente para amparar as conclusões destes relatórios, efetuou-se pesquisa bibliográfica para dar suporte às conclusões. Identificaram-se similaridades entre estudos de alguns autores e análises amostrais de testes padronizados de tração e enrolamento sobre o próprio eixo de outubro 2010 a setembro de 2011. Os resultados mostraram que o fenômeno que induz a um elevado índice de quebra do arame Cultura Aérea é o envelhecimento que ocorre posteriormente à sua passagem por elevadas reduções percentuais de área no processo de trefilação, que encrua o material, e em função de elevadas temperaturas encontradas no processo de galvanização, tendo, ainda, suas consequências amplificadas por pontos de concentração de tensões. Algumas soluções para amenizar a ocorrência do envelhecimento foram propostas, como o aumento do número de passes, o que reduz o encruamento, e a substituição do material por outro menos suscetível ao fenômeno, como um com menor percentual de carbono. / In the ongoing pursuit to meet demands of an increasingly competitive market, companies have to reduce all their losses in the production process, therefore reducing costs and adding margin to their products. The main goal of this study was to investigate the phenomena present in the occurrence of ruptures of products originated from drawn and galvanized SAE 1057B steel, used in aerial cultivation. The study uses literature and laboratory research and a sample of thirty-six report concerning galvanized final and drawn intermediate product behavior. The data reference to product failure in any stage of the productive process or in field application. Along with testing a bibliographical research was made for conclusion support . Similarities were found between some authors studies and sample analysis of standardized tensile tests and winding over own axis tests from October 2010 to September 2011. The results shown that the primary phenomenon inducing wire failure in aerial cultivation wire is alignment of the hardening due to the high percentage area reductions in the drawing process that allows the development of the strain aging phenomenon after the hot dip galvanizing process witch has it´s effects enhanced by stress concentration points. Some solutions to mitigate the strain aging were proposed, like increasing the number of reduction passes for hardening reduction and the use of less susceptible material to the phenomena as a lower percentage carbon steel.

Na busca contínua de atender as exigências de um mercado cada vez mais competitivo, as empresas devem buscar diminuir todas as suas perdas em seus processos produtivos, reduzindo custos e ganhando margem em seus produtos. Este trabalho teve como objetivo investigar os fenômenos presentes na ocorrência de quebras dos produtos derivados do aço SAE 1057B trefilado e galvanizado utilizado em culturas aéreas. O estudo utilizou bibliografia documental, pesquisa de laboratório e uma amostra composta por trinta e seis relatórios de análises sobre o desempenho do produto intermediário trefilado, ou do produto final galvanizado. Os dados referem-se à eventos de falhas do produto em quaisquer etapas do processo produtivo e mesmo de aplicação em campo. Juntamente com ensaios efetuados especificamente para amparar as conclusões destes relatórios, efetuou-se pesquisa bibliográfica para dar suporte às conclusões. Identificaram-se similaridades entre estudos de alguns autores e análises amostrais de testes padronizados de tração e enrolamento sobre o próprio eixo de outubro 2010 a setembro de 2011. Os resultados mostraram que o fenômeno que induz a um elevado índice de quebra do arame Cultura Aérea é o envelhecimento que ocorre posteriormente à sua passagem por elevadas reduções percentuais de área no processo de trefilação, que encrua o material, e em função de elevadas temperaturas encontradas no processo de galvanização, tendo, ainda, suas consequências amplificadas por pontos de concentração de tensões. Algumas soluções para amenizar a ocorrência do envelhecimento foram propostas, como o aumento do número de passes, o que reduz o encruamento, e a substituição do material por outro menos suscetível ao fenômeno, como um com menor percentual de carbono. / In the ongoing pursuit to meet demands of an increasingly competitive market, companies have to reduce all their losses in the production process, therefore reducing costs and adding margin to their products. The main goal of this study was to investigate the phenomena present in the occurrence of ruptures of products originated from drawn and galvanized SAE 1057B steel, used in aerial cultivation. The study uses literature and laboratory research and a sample of thirty-six report concerning galvanized final and drawn intermediate product behavior. The data reference to product failure in any stage of the productive process or in field application. Along with testing a bibliographical research was made for conclusion support . Similarities were found between some authors studies and sample analysis of standardized tensile tests and winding over own axis tests from October 2010 to September 2011. The results shown that the primary phenomenon inducing wire failure in aerial cultivation wire is alignment of the hardening due to the high percentage area reductions in the drawing process that allows the development of the strain aging phenomenon after the hot dip galvanizing process witch has it´s effects enhanced by stress concentration points. Some solutions to mitigate the strain aging were proposed, like increasing the number of reduction passes for hardening reduction and the use of less susceptible material to the phenomena as a lower percentage carbon steel.

Na busca contínua de atender as exigências de um mercado cada vez mais competitivo, as empresas devem buscar diminuir todas as suas perdas em seus processos produtivos, reduzindo custos e ganhando margem em seus produtos. Este trabalho teve como objetivo investigar os fenômenos presentes na ocorrência de quebras dos produtos derivados do aço SAE 1057B trefilado e galvanizado utilizado em culturas aéreas. O estudo utilizou bibliografia documental, pesquisa de laboratório e uma amostra composta por trinta e seis relatórios de análises sobre o desempenho do produto intermediário trefilado, ou do produto final galvanizado. Os dados referem-se à eventos de falhas do produto em quaisquer etapas do processo produtivo e mesmo de aplicação em campo. Juntamente com ensaios efetuados especificamente para amparar as conclusões destes relatórios, efetuou-se pesquisa bibliográfica para dar suporte às conclusões. Identificaram-se similaridades entre estudos de alguns autores e análises amostrais de testes padronizados de tração e enrolamento sobre o próprio eixo de outubro 2010 a setembro de 2011. Os resultados mostraram que o fenômeno que induz a um elevado índice de quebra do arame Cultura Aérea é o envelhecimento que ocorre posteriormente à sua passagem por elevadas reduções percentuais de área no processo de trefilação, que encrua o material, e em função de elevadas temperaturas encontradas no processo de galvanização, tendo, ainda, suas consequências amplificadas por pontos de concentração de tensões. Algumas soluções para amenizar a ocorrência do envelhecimento foram propostas, como o aumento do número de passes, o que reduz o encruamento, e a substituição do material por outro menos suscetível ao fenômeno, como um com menor percentual de carbono. / In the ongoing pursuit to meet demands of an increasingly competitive market, companies have to reduce all their losses in the production process, therefore reducing costs and adding margin to their products. The main goal of this study was to investigate the phenomena present in the occurrence of ruptures of products originated from drawn and galvanized SAE 1057B steel, used in aerial cultivation. The study uses literature and laboratory research and a sample of thirty-six report concerning galvanized final and drawn intermediate product behavior. The data reference to product failure in any stage of the productive process or in field application. Along with testing a bibliographical research was made for conclusion support . Similarities were found between some authors studies and sample analysis of standardized tensile tests and winding over own axis tests from October 2010 to September 2011. The results shown that the primary phenomenon inducing wire failure in aerial cultivation wire is alignment of the hardening due to the high percentage area reductions in the drawing process that allows the development of the strain aging phenomenon after the hot dip galvanizing process witch has it´s effects enhanced by stress concentration points. Some solutions to mitigate the strain aging were proposed, like increasing the number of reduction passes for hardening reduction and the use of less susceptible material to the phenomena as a lower percentage carbon steel.

The unique combination of high specific strength and ductility in third generation advanced high-strength steels (3G-AHSSs) has garnered significant attention from top automotive steel industries. These materials are being considered as potential options for making lighter body components due to their strength and ability to tolerate thinner material cross-sections. However, galvanizing these steels through the continuous hot-dip galvanizing process is challenging, because the main alloying elements such as Mn, Si, Al, and Cr tend to selectively oxidize on the steel surface during the annealing process before being immersed in the galvanizing bath containing Zn(Al, Fe). The presence of these oxides extensively covering the substrate surface can negatively impact reactive wetting, coating adhesion, and overall coating quality. In this study, the selective oxidation kinetics and reactive wetting of a series of Fe-(2-10)Mn-(0.00/0.01/0.03)Sb (at. pct) were determined and a model was proposed for analyzing oxide growth during intercritical annealing prior to galvanizing. Annealing heat treatments were carried out at 676, 725, 775, and 825 ˚C for 60-480s holding time in a N2-5vol pct H2 process with a dew point of –10 ˚C. MnO was formed on all samples after annealing. It was determined that the annealing conditions (temperature and isothermal holding time) affected the external oxide thickness and depth of the oxidation zone, which in turn influenced the MnO growth rate. With increasing the bulk Mn content of the alloy, the Mn elemental flux to the external surface increased, resulting in an increase in the oxidation parabolic rate constant. The average activation energy of internal oxidation for the Fe-2Mn, Fe-6Mn and Fe-10Mn alloys were determined to be 216±15 kJ/mol, 178 ± 18 kJ/mol and 152 ±10 kJ/mol, respectively, which are consistent with the activation energy of oxygen diffusion through MnO interfaces and the bulk diffusion of oxygen in austenite. Moreover, the average activation energy for external oxide growth was ~113±18 kJ/mol, which was attributed to the diffusion of Mn cations along the grain boundaries of the external Mn oxides. It was determined that micro addition of Sb to the Fe-Mn alloys led to a reduction in the oxidation rate constant, external oxide thickness, and internal oxidation zone, which was attributed to Sb segregation at both the external and internal oxide interface, resulting in the reduction of oxygen permeability. The reduction was more significant in the Fe-10Mn alloys, primarily attributable to the increased Sb segregation at the interfaces. The research showed that when the bulk Mn content increased, more antimony (Sb) segregated at both the internal and external oxide/substrate interface. As a result, the oxygen present at these interfaces decreased. This is attributed to the reduction of Sb solubility in α-Fe with increasing Mn and positive interactions between Sb and Mn. Advanced Atom Probe Tomography (APT) analysis confirmed that as more Sb segregated at the interfaces, the excess oxygen reduced due to site competition between O and Sb. Additionally, Sb surface segregation kinetics for Fe-(0.01/0.03)Sb and Fe-2Mn-(0.01/0.03)Sb at.% were determined based on the modified Darken model and linear heating followed by isothermal annealing. After the annealing, Sb segregation was detected on the surface of both the Fe-xSb and Fe-2Mn-xSb alloys, which increase with increasing temperature and holding time. The segregation rate, as determined from the Darken curves, was higher in Fe-Sb alloys compared to Fe-2Mn-Sb alloys, which can be attributed to variations in the crystal structure and the density of defects within the metal matrix. Additionally, the activation energy for Sb diffusion in both Fe-Sb and Fe-2Mn-xSb alloys were determined to be approximately 193±18 kJ/mol closely aligns with the activation energy of Sb bulk diffusion in α-Fe. Simulated galvanizing treatments were conducted on Fe-(2-10)Mn-(0.00/0.03)Sb at.% alloys. It was found that Sb segregation at the external/oxide interface resulted in a decrease in the size and thickness of the external oxide particles, which can facilitate better contact between the zinc bath and the substrate. Furthermore, it was found that Sb segregation at the interface between the external oxide and substrate led to a decrease in the stability of the interfacial region. This effect was attributed to an increase in the local atomic spacing near the interface, caused by Sb segregation. As a result, a local strain was observed near the interface. This localized strain significantly reduced the energy needed to separate the oxide from the metal matrix, contributing to decreased stability of the interfacial region. The higher bulk manganese (Mn) content led to increased segregation of antimony (Sb), resulting in a greater local strain within the interfacial region. These effects, in turn, enhanced the kinetics of the aluminothermic reduction reaction and assisted oxide lift-off. Furthermore, the closely packed Fe-Al intermetallics at the coating/steel interface increased as a result of adding Sb to the steel. In addition, no Sb segregation was observed at interfacial layer/metal interface. This absence of segregation can be attributed to the dissolution of segregated Sb into the liquid zinc. It was determined that Sb, which segregated at the external oxide/substrate interface during annealing, dissolved into the zinc bath and disrupted its bond with iron. This disruption occurred due to the higher electronegativity of Sb compared to Fe with Zinc, as well as the sufficient solubility of Sb in liquid zinc. / Thesis / Doctor of Science (PhD) / The unique combination of high specific strength and ductility exhibited by third-generation advanced high-strength steels has captured the attention of automotive industries. However, challenges arise when attempting to galvanize these steels through continuous hot-dip galvanizing processes. The selective oxidation of alloying elements during annealing can have detrimental effects on reactive wetting and coating adhesion. The objective of this research was to improve the coating quality of Mn-containing steels by introducing micro-additions of Sb. Sb segregation to the surface and interfaces began to occur during annealing. Segregated Sb resulted in a reduction of the oxidation rate. Sb segregation at oxide interfaces also contributed to decreased oxygen permeability. Upon immersion in the liquid zinc bath, both Sb and Fe dissolved into the zinc, leading to the formation of an interfacial layer on the surface, which indicates successful reactive wetting. The findings of this research provide valuable insights for improving galvanizing processes and enhancing coating quality, specifically in the context of third-generation advanced high-strength steels.

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Uncoated defects in hot dip metal-coated steel products result from non-wetting of the steel surface by the molten alloy. The occurrence of uncoated defects is highly detrimental to product quality and production efficiency; uncoated defects compromise the appearance and anti-corrosion performance of hot dip metal-coated steel products and causes time delays in the application of subsequent surface treatments. Although many studies have been directed towards evaluating the effect of steel pre-heat temperature and oxidation on the formation of uncoated defects, fewer investigations have analysed how oil-derived residues remaining on steel surface following the cold rolling and furnace cleaning processes impact upon hot dip metallic coating quality. Furthermore, although a considerable amount of research has focussed on the process of deposit formation in lubricants used in other applications, the composition of oily residues remaining after the continuous annealing process, and the origins of these residues in the original rolling oil formulation, are poorly understood. The primary focus of the present work has been to gain an improved understanding of relationships between cold rolling oil composition, oil residue-formation characteristics and the occurrence of uncoated defects in 55Al-43.4Zn-1.6Si hot dip metallic coatings. Several key classes of rolling oil ingredients which decompose to leave high levels of thermally-stable residue have been identified. The thermal decomposition processes undergone by a variety ingredients within these classes have been studied under both oxidising and reducing conditions using Thermogravimetric Analysis (TGA) and Pressure Differential Scanning Calorimetry (PDSC) techniques, with chemical characterisation of the decomposition process and the resultant thermally-stable residue by infrared spectroscopy. Model blends of each ingredient in a typical cold rolling oil base ester have also been evaluated by TGA and PDSC to identify the impact of ingredient concentration and chemical structure on the amount of oily residue formed. The results of these investigations have been related to the impact of the ingredients on 55Al-43.4Zn-1.6Si hot dip metallic coating quality through the performance of industrial-scale hot dipping trials and hot dip simulation studies. In order to translate these results into a context more closely aligned with industrial conditions, the effect of processing variables, including furnace atmosphere and the availability/concentration of iron in contact with the rolling oil at the steel surface, on the decomposition process of a fully-formulated commercial cold rolling oil has also been investigated. The information gained can potentially be used to tailor operating conditions within the cold rolling/continuous hot dip metallic coating processes to enhance steel surface cleanliness. Finally, the deposit-forming tendencies of an array of different commercial cold rolling oils have been evaluated, leading to the development of a thermal analysis-based test for screening cold rolling oils with respect to their likely impact upon 55Al-43.4Zn-1.6Si hot dip metallic coating quality. This test, together with the understanding obtained on the effect of different rolling oil ingredients on hot dip metallic coating quality, can be used within the industry to formulate improved cold rolling oils.