Method of production of high-nitrogen ferritic heat-resisting steel

A method of producing a high-nitrogen ferritic heat-resisting steel comprising, in weight percent

• 0.01-0.30% C,
• 0.02-0.80% Si,
• 0.20-1.00% Mn,
• 8.00-13.00% Cr,
• 0.005-1.00% Mo,
• 0.50-3.00% W,
• 0.05-0.50% V,
• 0.02-0.12% Nb,
• 0.10-0.50% N,
• and one or both of
• 0.01-1.00% Ta and
• 0.01-1.00% Hf
• and being controlled to include
• not more than 0.050% P,
• not more than 0.010% S, and
• not more than 0.020% O,
• the remainder being Fe and unavoidable impurities,
• which process comprises melting and equilibrating the steel in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas, and thereafter casting or solidifying the steel in an atmosphere controlled to have a nitrogen partial pressure of not less than 1.0 ata and a total pressure of not less than 4.0 ata, with the relationship between the partial pressure p and the total pressure P.sub.t being
• 10.sup.P <P.sub.t.sup.0.37 +log.sub.10 6
• thereby obtaining sound ingot free of blowholes.

A method of producing a high-nitrogen ferritic heat-resisting steel comprising, in weight percent

• 0.01-0.30% C,
• 0.02-0.80% Si,
• 0.20-1.00% Mn,
• 8.00-13.00% Cr,
• 0.005-1.00% Mo,
• 0.50-3.00% W,
• 0.05-0.50% V,
• 0.02-0.12% Nb,
• 0.10-0.50% N,
• and one or both of
• 0.0005-0.10% Zr and
• 0.01-0.10% Ti
• and being controlled to include
• not more than 0.050% P,
• not more than 0.010% S, and
• not more than 0.020% O,
• the remainder being Fe and unavoidable impurities,
• which process comprises melting and equilibrating the steel in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas, and thereafter casting or solidifying the steel in an atmosphere controlled to have a nitrogen partial pressure of not less than 1.0 ata and a total pressure of not less than 4.0 ata, with the relationship between the partial pressure p and the total pressure P.sub.t being
• 10.sup.P <P.sub.t.sup.0.37 +log.sub.10 6
• thereby obtaining sound ingot free of blowholes.

A method of producing a high-nitrogen ferritic heat-resisting steel comprising, in wight percent

• 0.01-0.30% C,
• 0.02-0.80% Si,
• 0.20-1.00% Mn,
• 8.00-13.00% Cr,
• 0.005-1.00% Mo,
• 0.50-3.00% W,
• 0.05-0.50% V,
• 0.02-0.12% Nb,
• 0.10-0.50% N,
• one or both of
• 0.01-1.00% Ta and
• 0.01-1.00% Hf
• and one or both of
• 0.0005-0.10% Zr and
• 0.01-0.10% Ti
• and being controlled to include
• not more than 0.050% P,
• not more than 0.010% S, and
• not more than 0.020% O,
• the remainder being Fe and unavoidable impurities,
• which process comprises melting and equilibrating the steel in an atmosphere of a mixed gas of a prescribed nitrogen partial pressure or nitrogen gas, and thereafter casting or solidifying the steel in an atmosphere controlled to have a nitrogen partial pressure of not less than 1.0 ata and a total pressure of not less than 4.0 ata, with the relationship between the partial pressure p and the total pressure P.sub.t being
• 10.sup.P <P.sub.t.sup.0.37 +log.sub.10 6
• thereby obtaining sound ingot free of blowholes.