ABSTRACT
Copper-Aluminothermic weld is a process in which welder is generated by thermofusion. The necessary heat is obtained by the aluminum reducing effect above copper oxide, creating a high temperature exothermic reaction, in which melt and overheated copper is the filler material [11 WELDING HANDBOOK –Materials and applications Part 2, 8 ed., Editorial AWS, 1998.].This technique is used to joint rails in railway industry, in grounding welds [22 ARCIONI, J.C, GIMENEZ, J.F. “Las soldaduras cuproaluminotérmicas para puesta a tierra y sus ensayos eléctricos de calentamiento”, Revista electrotécnica, v. 274, pp. 86-91, Mar2013., 33 NORMA IRAM 2315*; Materiales para puesta a tierra – Soldaduracuproaluminotérmica, 2 ed., 1999.] and also in linepipes for cathodic protection. In this study copperaluminothermic weld is characterized for API 5L X46 and X52 steel linepipes for cathodic protection, considering two different thickness, changing the copper wire section and the flux amount. The purpose is to obtain the optimum welding conditions, therefore macroscopic and microscopic tests, and microhardness sweep are going to be performed on the heat affected zone. Twenty-five test tubes were realized, taking also into account different flux and gunpowder brands and melting pot sizes. An inadequate contact area can cause lack of pipe cathodic protection as well as an excessive copper diffusion into the grain boundaries can produce accelerated corrosion and microcracks in the base metal [44 LE DUC, E., LO CASTRO, B, LAVINAUD, B. “Method of Aluminothermic Welds Qualification for Down Conductors and Earth-Terminations Systems”, In:International Symposium on Lightning Protection. (XII SIPDA), pp. 345-347, Belo Horizonte, Brazil, October 7-11, 2013.,11 WELDING HANDBOOK –Materials and applications Part 2, 8 ed., Editorial AWS, 1998.], for that reason is necessary to obtain optimum welding conditions according to the steel grade and pipe thickness.
Keywords
Copper-aluminothermic; thermit-weld; cathodic protection weld
