Effects of post-oxidizing treatment on melting loss and corrosion resistance of gas nitrided AISI H13 tool steel

Abstract

This study conducted gas nitriding on AISI H13 steels, followed by oxidization treatments at various temperatures (560°C, 580°C, 600°C) and soaking times (1 h, 2 h, 3 h), to investigate the melting loss and corrosion resistance of A380 aluminum alloy. The experimental results indicated that the samples of oxynitriding (post-oxidizing treatment after nitrided) at 580°C for 3 h, 600°C for 2 h and 600°C for 3 h have better ability to resist melting loss due to their thicker oxidized layers. The weight loss rate also showed that they are near zero after a 4 h erosion test. The increasing weight loss rate is relative to the appearance of the Fe xAl ySi z compound. In addition, the difference in corrosion current is closely related to the corrosion rate. A smaller corrosion current will lead to a smaller corrosion rate. As a result, increasing the temperature and soaking time of oxidization is advantageous to the corrosion resistance, and a small variation in corrosion current will result in a significant change to the polarization resistance of corrosion. Consequently, the oxide layer can enhance the polarization resistance, and quickly generate a passivation layer that increases the corrosion resistance ability. © 2012 ISIJ.