Estudo da corrosão por fresta no aço inoxidável AISI 409 tratado por SHTPN

Abstract

It is estimated that corrosion is liable to affect 25% of world production of steel per year, and the economic losses due to this phenomenon may represent 2- 5% of the Gross Domestic Product (GDP). In Brazil, losses may reach about $ 10 billion, with much of the oil industry. In order to minimize the damage from corrosion in some applications such as food processing, chemical and petrochemical, stainless steels are used, which have high corrosion resistance, impact and abrasion, and great durability and wide applicability, however, are susceptible to pitting corrosion, intergranular, under fracture stress, under fatigue, by hydrogen and crack. This study proposes a new methodology for evaluating the crevice corrosion resistance of AISI 409 in its supply condition, treated by SHTPN (Solution heat treatment after plasma nitriding) and NSTR200 (SHTPN + Requenching + Tempering at 200 °C). The tests were performed in an electrochemical cell with crevice control adapted from the standards ASTM G 5, ASTM G 61 and ASTM G 150 ASTM F 746, which propose electrochemical cells and testing for the evaluation of pitting corrosion. The heat treatment showed a considerable improvement in corrosion resistance, having obtained the best result in the sample NSTR200, followed by SHTPN and supply condition. The proposed methodology shows promise, but some changes should be implemented in the electrochemical cell.