NASCIMENTO, A. B.; http://lattes.cnpq.br/4031797343700787; NASCIMENTO, Adriana Bispo do.
Resumo:
This work aimed to study the susceptibility to hydrogen embrittlement of dissimilar welded
joints, used in offshore sector of oil industry. For this weld beads were previously deposited
in segments of quenched and tempered AISI 8630 steel used in submarine valve, with two
different composition (standard and modified) using the automatized GMAW process. AWS
ERNiCrMo-3 wire with 1.2 mm diameter commercially known as Inconel 625, was used as
filer metal. The segments were subsequently subjected to post welding heat treatment
(PWHT) at 650 ° C for 3 hours and 676 ° C for 1h. After this the samples were subjected to
welding union, also using the same wire and welding process. After welding union tension
samples were drawn for hydrogenation test using the same condition of cathodic protection
used in submarine application. The test samples were subjected to hydrogenation by seven
days, and then immediately were placed in the tensile test to evaluate as hydrogen inserted
into the microstructure affects its mechanical properties. The results showed that thermal
cycle of the PWHT promote a significative influence. It was also observed that the PWHT
650 ° C for 3 hours promoted a greater formation of partially diluted areas, making the
microstructure of the region next to the fusion line harder. The specimens machined from
the standard AISI 8630 showed higher susceptibility to hydrogen embrittlement.