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ResumoOs aços inoxidáveis duplex conferem uma excelente resistência à corrosão e elevada resistência mecânica em um só material devido sua microestrutura bifásica formada pelas fases de ferrita e austenita numa proporção em torno de 50% para cada uma. Esse balanceamento de fases é devido à distribuição controlada de elementos formadores de austenita (gamagênicos) e de ferrita (alfagênicos). No entanto quando submetidos a processos de soldagem sua microestrutura pode apresentar um desbalanceamento de fases além de formação de fases intermetálicas que prejudicam suas propriedades e limitam sua utilização. O presente estudo objetiva comparar dois processos de soldagem autógenos (TIG e topo a topo por resistência) no aço UNS S32304 focando principalmente microestrutura pós-soldagem da zona afetada termicamente e no cordão de solda. Palavras-chave: Solda por resistência; UNS S32304; Ferrita. COMPARISON BETWEEN WELDING JOINTS OF DUPLEX STAINLESS STEEL (UNS S32304) PERFORMED BY RESISTANCE WELDING PROCESS AND AUTOGENOUS TIG WELDING AbstractDuplex stainless steel presents a good performance at corrosion enviroments, as well a high mechanical resistance due to their microstructure composition formed by ferrite and austenite in a proportion around 50%. This phase partition is due to a controlled distribution of austenite forming elements (gamagenics) and ferrite (alphagenics). However after the welding process, the final microstructure can present a higher ferrite content, and in addition can precipitate some intermetalic phases that are harmfull and limits its use. The present study aims compare two autogenous welding process (TIG and resistance welding) in steel UNS S32304 focusing mainly on the microstructure of the heat affected zone and weld bead after welding process.

ResumoEstudos recentes indicam que o gasto devido à corrosão nos USA giram em torno de 276 bilhões de dólares por ano, isto significa 3,1% do PIB deste país, tendo a corrosão atmosférica uma importante parcela deste montante. Muitos estudos foram realizados a fim de determinar a agressividade da atmosfera e avaliar os efeitos da corrosão atmosférica nos metais usados para aplicações estruturais. Este artigo tem como objetivo comparar dois ambientes em termos de severidade da atmosfera, assim como sua influência na degradação do aço estrutural ASTM A-572 Grau 50. Toma-se como cenário a planta industrial da Medabil Sistemas Construtivos, localizada em Serra, região metropolitana de Vitória/ES. O estudo foi realizado por meio de monitoramento de perda de massa de amostras expostas deste material e comparação dos resultados com os obtidos através do teste padrão proposto pela American Society for Testing and Materials (ASTM G116, 1999), Wire-on-Bolt Test for Atmospheric Galvanic. Palavras-chave: Corrosão atmosférica, ASTM A572 GRAU 50, Wire-on-Bolt. INFLUENCE OF TWO DIFFERENT ENVIRONMENTS AT THE CORROSION RATE OF STRUCTURAL STEEL ASTM A572 GRADE 50 AbstractRecent survey have indicated a significative cost loss due to corrosion in the USA, this amount is around 276 billion dollars per year, this means 3.1% of the GDP of this country, and atmospheric corrosion a significant portion of this amount. Many studies have been conducted in order to determine the aggressiveness of the environment and to evaluate the effects of atmospheric corrosion of metals used for structural applications. This article aims compare two environments in terms of severity of the atmosphere as well influence on the degradation of structural steel ASTM A-572 Grade 50. Medabil Building Systems, located in Serra, metropolitan area Vitória / ES was the source of this present paper. The study was performed at the exposed specimens, the weight was monitored and the results were compared with those obtained through the pattern proposed by the American Society for Testing and Materials (ASTM G116, 1999), Wire-on-Bolt Test for atmospheric Galvanic.

This work aims to implement and evaluate the effectiveness of the semi-analytical computational method global incremental wear model (GIWM) in predicting the sliding wear of rails in contact with the flange of railway wheels during curves, which is a parameter of great importance for the efficiency of railway operation. The method validation was performed by comparing the wear depth calculated using the GIWM algorithm to the experimental results published in previous work. The data was obtained in dry (relative humidity: 55% ± 10%) pin-on-disc tests carried out on a universal PLINT TE67 tribometer under a normal load of 24.6 N, representing 1.5 GPa of contact pressure. The specimens, hemispherical pins, were extracted from a pearlitic steel rail and the discs were extracted from two different, forged and cast, Class C railway wheels. The tangential sliding speeds were 0.1 m/s and 0.9 m/s, the latter being the most representative according to the literature. The wear model was based on Archard's law for sliding wear and the algorithm was implemented in Python. The results showed good agreement of the wear depth values between the computational and experimental methods for the cast wheel material under higher sliding speed, partial agreement for both wheel materials at lower speed and inconsistency for the forged wheel material under higher sliding speed. Furthermore, the algorithm is computationally efficient, presenting simulation time up to 180 times less than the finite element methods reported in the literature. Therefore, it was concluded that the GIWM method has potential for application in the freight railway sector, which uses cast wheels extensively, to guide technical areas regarding the wear behavior of rails under sliding contact during curves.