Abstract
AI5I 316L type sintered stainless steel specimens were produced in a continuous industrial furnace at 1180°C using a dissociated ammonia atmosphere. Copper was used as alloying element in different percentages (2, 4, 9%). Compacting pressure and sintering time were varied to study their combined effect on the corrosion behaviour of sintered stainless steels in a sulphuric acid solution. In this environment, the electrochemical behaviour depends in particular on the interconnected porosity and the precipitation of chromium rich phases. The compaction pressure affects markedly the amount and morphology of the open porosity, reducing the total exposed area, whereas a sintering time increase induces, in the present experimental conditions, more intense chromium nitride precipitation. Alloying with copper shows some benefits for the corrosion resistance of the sintered stainless steel, significantly reducing chromium nitride precipitation. Further, if added in an amount sufficient to give some free copper, it will promote passivation of the steel by depolarising the cathodic reactions.
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