Enhanced corrosion resistance of AISI H13 steel treated by nitrogen plasma immersion ion implantation

Electrochemical corrosion measurements of AISI H13 steel treated by Pill process in 3.5% (wt) NaCl solution were investigated. So far the corrosion behavior of AISI H 13 steel by Pill has not been studied. The electrochemical results are correlated with the surface morphology, nitrogen content and hardness of the nitride layer. Ion implantation of nitrogen into H 13 steel was carried out by Pill technique. SEM examination revealed a generalized corrosion and porosity over all analyzed sample surfaces. Penetration of nitrogen reaching more than 20 gm was achieved at 450 degrees C and hardness as high as 1340 HV (factor of 2.7 enhancement over standard tempered and annealed H 13) was reached by a high power, 9 h Pill treatment. The corrosion behavior of the samples was studied by potentiodynamic polarization method. The noblest corrosion behavior was observed for the samples treated by PIII at 450 degrees C, during 9 h. Anodic branches of polarization curves of PIII processed samples show a passive region associated with the formation of a protective film. The passive region current density of PIII treated H13 samples (3.5 x 10(-6) A/cm(2)) is about 270 times lower than the one of untreated specimens, which demonstrates the higher corrosion resistance for the Pill treated H 13 samples. (c) 2007 Elsevier B.V. All rights reserved.