Resumo: Aços carbono são revestidos com Inconel 625® para atender os requisitos de projeto no Pré-Sal. Entretanto, isso gera microrregiões conhecidas como a zona não misturada (ZNM) e a zona parcialmente misturada (ZPM) sendo a sua formação relacionada a dissimilaridade entre o metal de base e o metal de adição. O objetivo desse artigo é analisar o efeito da diluição, da ZPM e da ZNM e do reaquecimento dessas microrregiões sobre a resistência ao arrancamento do aço 9%Ni revestido com a liga Inconel 625®. A ZNM tem direções cristalográficas similares a ZAC e é CCC igual a ZAC. A ZPM apresenta direções cristalográficas mais heterogêneas quando comparadas ao metal de solda e é CFC igual ao metal de solda. A nanodureza da ZPM é similar a ZAC e até 42,5% maior que o metal de solda. A nanodureza da ZNM é até 14,9% menor que ZPM, até 48,2% menor que o metal de solda e até 15% menor que a ZAC. Todos os corpos de prova tiveram a propagação da trinca no metal de solda e atendem o requisito de 140 MPa mínimo para a tensão de cisalhamento. A diluição apresenta uma correlação com a tensão de cisalhamento.

Abstract: Carbon steels are coated with Inconel 625® to comply the pre-salt project requirements. However, this generates micro-regions such as the unmixed zone (UMZ) and a partially mixed zone (PMZ), with the formation related to the dissimilarity between the base metal and the addition metal. The purpose of this article is the analyze of the effect of dilution, PMZ and UMZ and the reheating of these micro-regions on the pullout resistance of 9% Ni steel coated with the Inconel 625® alloy. The UMZ has similar crystallographic directions to the heat affected zone (HAZ) and is BCC equal to HAZ. The PMZ presents more heterogeneous crystallographic directions when compared to the weld metal and is FCC equal to the weld metal. The PMZ nano-hardness is similar to HAZ and up to 42.5% greater than the weld metal. UMZ's nano-hardness is up to 14.9% less than PMZ, up to 48.2% less than weld metal and up to 15% less than HAZ. All specimens had crack propagation in the weld metal and comply the requirement of 140 MPa minimum for shear stress. The dilution presents a correlation with the shear stress.

Abstract Polymer matrix nanocomposites (NMP) have attracted a great interest mainly in the automotive, aerospace and medical industries since they have good mechanical properties, dimensional, thermal and chemical stability, as well as interesting electrical conductivity and cost reduction in the manufacturing process. However, welding of this class of materials presents serious challenges such as improving weldability of the joint and understanding the mechanisms responsible for coalescence. The objective of this work was to evaluate the coalescence of an NMP joint (comprising a PA6 matrix and with nanosilica of different percentages of silicon) using ultrasonic welding, as well as to perform an acoustic approach of the energy dissipation during the welding process. It is concluded that the NMP samples tend to show better coalescence as the percentage of nanosilica increases, up to a certain limit. On the other hand, the higher the content of nanoparticle the smaller the energy absorption.