A STUDY OF THE INFLUENCE OF NITRIC-ACID CONCENTRATION ON THE CORROSION-RESISTANCE OF SINTERED AUSTENITIC STAINLESS-STEEL

The influence of various concentrations of HNO3 (10, 20, 35 and 65%) a t 298 K on the corrosion resistance of powder metallurgy (P/M) fabrica ted AISI 304L and AISI 316L austenitic stainless steels has been studi ed. For comparison purposes a simultaneous study was carried out on si milar composition cast AISI 304L and ATSI 316L steels. Electrochemical spectroscopy was the technique chosen for this investigation and valu es for the Tafel dopes and the Stern-Geary constant B were obtained us ing polarization resistance. The sintered AISI 304L and AISI 316L stee ls had similar corrosion rates, with the highest being observed in the 65% HNO3 solution. The differences in corrosion rates between the P/M and cast steels are of two orders of magnitude. The attack on the PIM specimens is in the pores whilst negligible corrosion is observed on the cast materials. Copyright (C) 1996 Eisevier Science Ltd