Investigation into the Hot salt corrosion of Cr?Al,Cr?Ni?Mn and Mn?Al steels

The hot salt corrosion behaviour in a KCl · K₂SO₄ · Fe₂O₃ melt at 755 °C has been investigated as a function of alloy composition for three groups of refractory steels: 24Cr1.3Al, 27Cr12Ni(4 or 6)Mn and (20: 33)Mn(7 : 10)Al. Mn. Al-steels with a maximum Mn-content of 30% and CrNi6Mn-steels displayed a marked superiority in corrosion resistance in terms of weight loss as well as depth of internal deterioration. The protective mechanism of manganese is apparently related to its high-rate uniform segregation to the metal/melt interface inhibiting internal sulphidation along preferential paths.