Proceedings of COBEM 2009 20th International Congress of Mechanical Engineering Copyright © 2009 by ABCM November 15-20, 2009, Gramado, RS, Brazil ANALYSIS OF THE DISCONTINUITIES GENERATED IN MULTIPASSE WELDS IN V GROOVE FCAW AND FCAW-CW PROCESS Noêmia Ferreira Leal, nfleal2000@yahoo.com.br Carlos Alberto Mendes da Mota, cmota@ufpa.br Anne Caroline Melo de Alcântara, acmamecanica@hotmail.com Luciana Gaspar Feio, lu_gaspar@hotmail.com Cássio Patrick Nunes Mendes, tick_mendes@yahoo.com.br UFPA – Universidade Federal do Pará / GETSOLDA Rua Augusto Correa, Nº 1. Campus Universitário Guamá. CEP 66075-110. Caixa postal 479. PABX +55 91 3201-7000. Belém- Pará - Brasil. Alexandre Saldanha do Nascimento, saldanha77@yahoo.com.br UFU - Universidade Federal de Uberândia / LAPROSOLDA Avenida João Naves de Ávila, 2121. Uberlândia - Minas Gerais – Brasil. Campus Santa Mônica, Bloco 1M. CEP 38400-902 Abstract. This work studied the presence of discontinuities in two welded joints by multiple passes, deposited by the processes tubular wire (FCAW) and tubular wire with cold wire addition (FCAW-CW). The inspections were performed by non-destructive tests of liquid penetrant and ultrasound, besides macrograph in cross section of solder. The manual welding was done with a electronic source with DC + in flat position on steel joints ABNT 1020 of 350X350X16, 4 mm and chamfer V with 60 ° filled with five passes. As addition metals were used wires AWS E71T-1 and AWS ER70S-6, respectively, and diameter 1.2 mm. The protection gas was CO 2 , at 15 L/min. The results indicated the presence of slag inclusion between the passes in the two solder cases studied, and insufficient deposition in the weld process by tubular wire. These discontinuities occurred because the cleaning and / or the manipulation of the electrode during the deposition. Although the results showed an increased incidence of discontinuities in FCAW-CW welding related to FCAW, the found level were tolerable based on criteria of standards consulted, which, by minor adjustments on equipment and welding techniques here used, can provide to the FCAW-CW process improvements in quality of welds, indicating the feasibility of the process as an alternative to increase productivity combined with low costs. Keywords:FCAW,FCAW-CW,descontinuities. 1. INTRODUCTION The use of the tubular wire welding intensified in mechanical, naval and oil industry, both in the manufacture of structures such as the metal surfaces tooting, for its operational characteristics, versatility and high productivity. In the process of welding with wire tubular or Flux Cored Arc Welding (FCAW) the coalescence between metals occurs by the action of an electric arc formed between the electrode (wire) and the piece to be welded (base metal).The wire is made of a metal layer with an internal flow, it is fed until the merger pool. The process can be in two ways: with protective gas - a gas used as an ionizating acting and to protect the arc, and self-protected - where gas is generated from the decomposition of the ingredients contained in the flow, with functions to stabilize the arc, adding alloy elements in the metal welding, protecting the metal welding from by the action of deoxidizer and denitrifier acting and, besides the slag formation that will protect the weld during solidification, recent work (FORTES, 2004). The literature considers that the process FCAW is highlighted by presenting deposited metal and solder of high quality with good visual appearance. The quality of the weld will depend of the type of electrode used; method (self- protected or gas protected); conditions of the base metal conditions of the joint project and the process of welding. The design of the FCAW-CW welding process refers to a FCAW welding version with the cold wire addition. Is the insertion of a cold wire in the atmosphere of arc generated at the type of wire electrode of the conventional process (FCAW). Thus, the cold wire melts simultaneously with the wire electrode metal to be deposited. The proposal of the welding with cold wire is established as a technical and economical alternative for the conventional welding with continuous feeding of wire electrode. As an important difference between the dual processes of welding wire (conventional) and cold wire (in development) has the fact that the first two wire electrodes used to melt by the action of two voltaic arcs generated at its extremity in decay, while the second uses only one electrode wire for a single arc, the other wire is cold, not energized, recent work (GARCIA, 2009). As advantages of welding with cold wire are: gas economy, easy manipulation of the welding torch (Fig.1), being more compact and light, absence of the magnetic wind, reduced cost of equipment, work with different diameters of wire, reduction in emission of smoke and radiation, recent work (LEAL, 2009).