Análise da formação de trincas por solidificação em ligas cuproníquel submetidas ao ensaio trans-varestraint

Abstract

One of the problems observed in the oil and gas industry concerns the failure of CuNi pipes used in the construction of fire systems. Therefore, this research focuses on a CuNi alloy with wide use and that has gained prominence in the petroleum sector due to its distinct mechanical properties and its possible uses. Two alloys were studied in this project: the first is UNS C70600, composed of about 90% copper and 10% nickel and the second is composed of approximately 70% copper and 30% nickel, both alloys widely used in piping systems for fire fighting, heat exchangers and operation in salt water, among other functions. The study was aimed at presenting and comparing the data of hot crack generation by solidification when both alloys undergo the application of different levels of deformation. In the research, deformations of 2% and 8% and two different energies were applied through the Trans-Varestraint weldability test and the autogenous TIG welding process, respectively. The test provided important data for analysis, such as the longest crack length (MCL) and the total crack length (TCL). With the results, it was possible to observe similar values when analyzing the MCL during the 2% deformation, but a very different value, about 310% higher, when using the 8% deformation in relation to the TCL, it was observed in the alloys studied that both presented less than 1 mm difference in relation to the observed crack length, both in the deformation of 2% and in the deformation of 8%.