Influence of the Parameters on Submarine Manual Metal Arc Welding in the Properties on API 5L X-52 Steel Used on Pipe Li
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Influence of the Parameters on Submarine Manual Metal Arc Welding in the Properties on API 5L X-52 Steel Used on Pipe Line Hydrocarbons P. Hernández, J. L. Acevedo, C. A. Guevara, F. A. Reyes, F. Cepeda Corporación Mexicana de Investigación en Materiales S.A. de C.V., Ciencia y Tecnología #790. Fracc. Saltillo 400, C.P. 25290, Saltillo, Coahuila, México, (844) 4113200 Ext. 1215, Fax (844) 4113210, Email: [email protected] ABSTRACT This investigation examines the used parameters in the wet welding process, as well as his influence on the properties of welded union under manual metal arc welding process, obtained at 10m and 20m sea water deep, with an electrode E7024. The E7024 filler material is normally used in the reparation of hydrocarbon pipelines on deeps no more of 30m, however his chemical composition allow to use as material to repair in zones where the pressure is a paramount factor. A statistical design of experiments (DOE) with 36 coupons has been proposed using the travel speed, amperage and the underwater welding condition (10m and 20m) as input variables. To evaluate the quality of the welded unions, tensile, bend, hardness and metallographic test were carried out. The statistical analysis of DOE found that the amperage variable result to be the most influence parameter in the control of quality of the weld union. Besides this the technique of scanning electron microscopic was used to observe the kind of fractography showed in a crack throughout weld resulted from the bend test, and energy dispersive X-ray spectrometry to identify the present species in this zone. Keywords: Welding, Rapid Solidification, Scanning Electron Microscopy, Porosity, Water.
INTRODUCTION The under wet welding with Manual Metal Arc Welding (MMAW) process has proven to be a suitable repair process on offshore platforms, piers, ships, and nuclear power plants. One of the materials that are frequently used for these reparations is the API-5L-X52 [1,3].Wet welding is selected over repair options because it can be quickly mobilized with relatively simple equipment, thereby dramatically reducing of repair cost and time can we achieved [2]. However, the mechanical properties are not equal to those exhibited by dry welds [4]. Wet weld ductility decreases due to the porosity, and changes in chemical composition and microstructure were caused by the proximity between cold sea water and the weld pool, besides this high cooling rates are presented in the weld profile that are associated with the size and behavior of heat-affected zone[4]. There is an interest to understand the effect of welding parameters in this process, mainly because in this type of weld joints the formation of weld defects such, cracks, porosity and slag contamination usually happen [4,5]. Several researchers in this welding field are focused in the study of the porosity in the underwater welding [5,6,7], which is one of the defects inherent of this process due to the conditions where is performed. However, nowadays there is lack on the study of the behavior of the pa
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