![]() ![]() However, as austenitic steels, they appear to be sensitive to liquid zinc embrittlement during welding, the liquid zinc arising from the melted coating due to the high temperatures reached during the welding process. High manganese TWIP (TWinning Induced Plasticity) steels are particularly attractive for automotive applications because of their exceptional properties of strength combined with an excellent ductility. The results of this study provide guidance to engineers, galvanizers, and fabricators to minimize steel plate girder distortion so that they can more confidently use hot-dip galvanizing to protect their bridges, and the paper describes a modeling methodology that will enable future research in this field. ![]() Dipping speed was also identified as an important parameter for reducing distortion, and faster dipping and extraction speeds resulted in less distortion during and after galvanizing. It was found that welding in the vertical position corresponded to the least distortion during galvanizing, especially for unstiffened plate girders. In addition, galvanizing dipping and extraction speed, dwell time in the zinc bath, and dipping angle were examined as parameters. Three methods of welded fabrication were studied: welding in lay-down position, welding in the trough, and welding in the vertical position. This paper, the second of a two-part series, presents a parametric study investigating the influence of welding and galvanizing practices on the susceptibility of welded plate girders to distortion during and after galvanizing. Several experimental results and case studies are presented to understand the embrittlement and fracture of galvanized steels. The numerous factors are broadly categorized as (i) pre-treatment and galvanizing process, (ii) properties of the steel to be coated, (iii) properties of the galvanizing bath, (iv) galvanizing process parameters, (v) fabrication process and (v) service condition. In this respect, the various mechanisms and the factors affecting them during and after galvanizing are discussed in this paper. For failure analysis to be carried out, it is important that the background and service history of any component is thoroughly understood. Failure of galvanized steels can take place by several mechanisms such as liquid metal embrittlement (LME), hydrogen embrittlement (HE), distortion cracking and strain age embrittlement. However, modification in the zinc bath composition, more advanced structural designs, along with demanding service conditions have resulted in increased instances of failure of galvanized steels. Hot dip galvanizing is one of the most economically viable zinc coating techniques, developed over 200 years ago. Zinc coated steels are widely used in automotive and construction industries, due to their superior corrosion resistance compared to uncoated steels. #GALVANIZED STEEL STRESS CORROSION CRACKING MECHANISM CRACK#As a final result, the authors propose the key points of a qualitative failure model which consists of a first step of accumulation of Sn and Pb in crack tips, a second step of production of FeSn compound, and a final step of FeSn cracking due to accumulated stresses. Microscopy revealed intergranular propagation and the existence of an intermetallic compound, the FeSn, at the crack tips. The failure assessment diagram (FAD) of the steel for two different load conditions. The subcritical crack propagation rate (da/dt)II and 3. The value of the threshold stress intensity factor, Kth, which is the lowest value to produce cracking 2. Besides, crack characterization tests on steel CT specimens which are immersed in liquid galvanization bath with Zn, 1.1% Sn and 0.1% Bi at 450☌ are detailed. Hydrogen influence is discarded after the hydrogen concentration tests performed in this paper. Traditionally two processes have been related with this phenomenon: liquid metal assisted cracking and hydrogen embrittlement. ![]() Failures during hot-dip galvanizing are occasionally, but they are important because of the high responsibility of the evolved structures. ![]()
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