Fe-Ni-Cr BASED ALLOY EXCELLENT IN CORROSION RESISTANCE RO SULFURIC ACID, INTERGRANULAR CORROSION RESISTANCE AND SURFACE PROPERTIES AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an Fe-Ni-Cr based alloy excellent both in corrosion resistance and surface properties and a method for producing the same.SOLUTION: There is provided a method for producing an alloy having a component composition containing, in terms of mass%, C:0.001 to 0.07%, Si:0.1 to 1.0%, Mn:0.1 to 2.0%, Ni:30 to 40%, Cr:18 to 23%, Mo:1 to 5%, Cu:1 to 5%, Nb:0.2 to 1%, Al:0.01 to 0.5%, Mg:0.0001 to 0.01%, Ca:0.0001 to 0.01% and O:0.0001 to 0.01% in which the crude molten steel of an Fe-Ni-Cr based alloy is decarburize-refined and then subjected to Cr reduction and preliminary deoxidation by adding Si and subsequently a CaO-SiO-AlO-MgO-F based slag is generated by adding lime and fluorite to perform deoxidation and desulfurization and followed by adding Nb, where the nonmetallic inclusion is composed of only one or two or more of CaO-MgO-AlO, MgO and MgO.AlO.