Surface modification of steel and cast iron to improve corrosion resistance in molten aluminium

In the present investigation, molten aluminium corrosion tests have been performed on boronised samples of duplex 22Cr–5Ni stainless steel, hot work steel (AISI H13) and nodular cast iron, and on a non-boronised γ-TiAl sample as a reference. The experimental results show that the corrosion rate, as expressed in terms of volume loss per square centimetre of the specimen per hour, was reduced with boronising by a factor of 16 and 20 for the nodular cast iron and the duplex stainless steel, respectively. Apparently, the corrosion resistance becomes better than that of TiAl under the prevailing conditions. For the AISI H13 tool steel, the corrosion rate was reduced by a factor of 3. The corrosion mechanisms involved are discussed in terms of diffusion rate controlling elements.