Corrosion behaviour and microstructure evolution of 17-4 PH stainless steel foam

Abstract

This study describes corrosion behaviour and microstructure evolution of 17-4 PH stainless steel foam, which was produced for biomedical implant applications. 17-4 PH stainless steel foam was produced by the space holder-sintering technique. The effect of boron addition, aging, sintering temperature and sintering time on the corrosion behaviour and microstructure of the 17-4 PH stainless steel foam was investigated. Microstructure of the 17-4 PH stainless steel foams was examined by using scanning electron microscope (SEM) and optical microscope. The corrosion behaviour of the 17-4 PH stainless steel foam was investigated by using neutral salt spray (fog) and accelerated aging tests. The 17-4 PH stainless steel foams were exposed to salt spray solution, which consisted of 5% NaCl with pH of 6.68, in a closed cabin at 35 degrees C. The surface of the foams after the corrosion test was observed by optical microscope and the digital photographs were analysed by an image analyser. The corrosion resistance of boron-added foams was higher than boron-free 17-4 PH stainless steel foams. Aging heat treatment slightly decreased the corrosion resistance of the 17-4 PH stainless steel foams. Increasing sintering temperature and sintering time increased the corrosion resistance of the stainless steel foams.