Propriedades mecânicas e de resistência à corrosão das juntas de aços inoxidáveis duplex e superduplex soldadas por processos a arco elétrico : uma revisão na literatura

Abstract

Duplex stainless steels (DSS) and superduplex stainless steels (SDSS) stainless steels are steel alloys with a biphasic microstructure formed by approximately 50% austenite (γ) and 50% ferrite (α), this balancing combined with its composition guarantees these steels good mechanical properties and excellent corrosion resistance being widely applied in chemical and petrochemical industries. Welding is present in the manufacturing and maintenance processes of DSS and SDSS parts and equipment, and the temperatures and thermal cycles caused by this process can impair its properties and compromise its application. Thus, the present work aims, through a literature review, to identify how the welding parameters can influence the transformations that occur during the welding process of DSS and SDSS, and how the mechanical properties and corrosion resistance will be affected due to these transformations. To this end, a review of the scientific literature was carried out, which showed that the parameters that affect the microstructural transformations in DSS and SDSS, such as imbalance in the proportion of austenitic and ferritic phases, and consequent alteration of their properties such as toughness, are those that alter the cooling speed of the material after welding such as: welding energy, welding current and welding speed. In the materials found, the effects of varying welding parameters on both the microhardness of duplex and superduplex stainless steels and the critical pitting temperature (CPT) were not conclusive, however, a greater predisposition to corrosion was found in samples welded with higher welding energies. It is evident that, in order to preserve the original characteristics of the DSS and SDSS, it is necessary to control the welding parameters in order to ensure the chemical composition, phase balancing and avoid the precipitation of deleterious phases in these materials.