A ferritic stainless steel sheet includes a base metal and a nitrided layer that is formed on a surface of the base metal, a chemical composition of the base metal contains, in mass %, C: 0.001 to 0.020%, Si: 0.01 to 1.50%, Mn: 0.01 to 1.50%, P: 0.010 to 0.050%, S: 0.0001 to 0.010%, Cr: 16.0 to 25.0%, N: 0.001 to 0.030%, Ti: 0.01 to 0.30%, and optional elements, with the balance: Fe and unavoidable impurities, a steel microstructure of the base metal includes, in volume ratio, 95% or more of a ferritic phase, the nitrided layer is a layer that is present in a region from a surface of a rolled surface to a 0.05 μm depth position in a sheet thickness direction, and an average nitrogen concentration in the nitrided layer is, in mass %, 0.80% or more.

A ferritic stainless steel sheet includes a base metal and a nitrided layer that is formed on a surface of the base metal, a chemical composition of the base metal contains, in mass %, C: 0.001 to 0.020%, Si: 0.01 to 1.50%, Mn: 0.01 to 1.50%, P: 0.010 to 0.050%, S: 0.0001 to 0.010%, Cr: 16.0 to 25.0%, N: 0.001 to 0.030%, Ti: 0.01 to 0.30%, and optional elements, with the balance: Fe and unavoidable impurities, a steel microstructure of the base metal includes, in volume ratio, 95% or more of a ferritic phase, the nitrided layer is a layer that is present in a region from a surface of a rolled surface to a 0.05 μm depth position in a sheet thickness direction, and an average nitrogen concentration in the nitrided layer is, in mass %, 0.80% or more.

The present invention provides a method of heat treating a steel component including the sequential steps of: (a) carbonitriding the steel component; (b) quenching the steel component; (c) optionally tempering the steel component; and (d) ferritically nitrocarburizing the steel component.

The present invention provides a method of heat treating a steel component including the sequential steps of: (a) carbonitriding the steel component; (b) quenching the steel component; (c) optionally tempering the steel component; and (d) ferritically nitrocarburizing the steel component.

A motor vehicle component and a method of manufacturing thereof is disclosed having at least regionally high-strength and at the same time ductile properties, including providing a sheet metal blank composed of a hardenable steel alloy with at least 0.25% carbon fraction, at least partially heating the sheet metal blank to above austenitizing temperature, in less than 20 seconds, hot-forming and press-hardening the sheet metal blank, in the process, setting a tensile strength Rm of greater than 1800 MPa and an elongation at break A20 of greater than 6%.

A motor vehicle component and a method of manufacturing thereof is disclosed having at least regionally high-strength and at the same time ductile properties, including providing a sheet metal blank composed of a hardenable steel alloy with at least 0.25% carbon fraction, at least partially heating the sheet metal blank to above austenitizing temperature, in less than 20 seconds, hot-forming and press-hardening the sheet metal blank, in the process, setting a tensile strength Rm of greater than 1800 MPa and an elongation at break A20 of greater than 6%.

The present invention provides a nitriding treatment method for forming a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride excellent in wear durability in a steel material, from which a sliding member is formed, by short treatment, with a high thermal efficiency, with a reduced amount of used nitriding gas, and with a low environmental load. The nitriding treatment method of the present invention includes heating a sliding member made of a steel material at a temperature of 600° C. to 700° C. for a time of 1 to 25 minutes under an atmosphere of nitriding gas through high frequency induction heating or resistive heating, to form a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride, the compound layer having a nitrogen content of higher than 4.5%, in a surface layer portion of the sliding member.

The present invention provides a nitriding treatment method for forming a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride excellent in wear durability in a steel material, from which a sliding member is formed, by short treatment, with a high thermal efficiency, with a reduced amount of used nitriding gas, and with a low environmental load. The nitriding treatment method of the present invention includes heating a sliding member made of a steel material at a temperature of 600° C. to 700° C. for a time of 1 to 25 minutes under an atmosphere of nitriding gas through high frequency induction heating or resistive heating, to form a compound layer of ε phase (Fe.sub.2-3N) and γ′ phase (Fe.sub.4N) iron nitride, the compound layer having a nitrogen content of higher than 4.5%, in a surface layer portion of the sliding member.

A case hardening steel includes a chemical composition containing C: 0.10 mass % to 0.35 mass %, Si: 0.01 mass % to 0.13 mass %, Mn: 0.30 mass % to 0.80 mass %, P: 0.02 mass % or less, S: 0.03 mass % or less, Al: 0.01 mass % to 0.045 mass %, Cr: 0.5 mass % to 3.0 mass %, B: 0.0005 mass % to 0.0040 mass %, Nb: 0.003 mass % to 0.080 mass %, N: 0.0080 mass % or less, Ti as an impurity: 0.005 mass % or less, and the balance being Fe and incidental impurities, and satisfying Formulae (1) and (2):
3.0[% Si]+9.2[% Cr]+10.3[% Mn]≥10.0  (1)
3.0[% Si]+1.0[% Mn]<1.0  (2) where [% M] represents the content of element M (mass %).

A case hardening steel includes a chemical composition containing C: 0.10 mass % to 0.35 mass %, Si: 0.01 mass % to 0.13 mass %, Mn: 0.30 mass % to 0.80 mass %, P: 0.02 mass % or less, S: 0.03 mass % or less, Al: 0.01 mass % to 0.045 mass %, Cr: 0.5 mass % to 3.0 mass %, B: 0.0005 mass % to 0.0040 mass %, Nb: 0.003 mass % to 0.080 mass %, N: 0.0080 mass % or less, Ti as an impurity: 0.005 mass % or less, and the balance being Fe and incidental impurities, and satisfying Formulae (1) and (2):
3.0[% Si]+9.2[% Cr]+10.3[% Mn]≥10.0  (1)
3.0[% Si]+1.0[% Mn]<1.0  (2) where [% M] represents the content of element M (mass %).