Abstract: A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 ?m/s and to obtain an ingot of low alloy steel.

Abstract: A method of fabricating a nitrided low-alloy steel part, includes a) decarburizing the surface of a low-alloy steel part including at least one alloying element that is both nitride-forming and carbide forming in order to obtain a decarburized part presenting a carbon-depleted surface layer of thickness less than or equal to 1.5 mm, the minimum content of carbon by weight in the carbon-depleted surface layer being less than or equal to 70% of the carbon content by weight in the core of the decarburized part; b) treating the decarburized part with quenching treatment followed by annealing treatment; and c) nitriding the carbon-depleted surface layer in order to obtain a nitrided low-alloy steel part, step c) being performed after step b).

Abstract: A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 ?m/s and to obtain an ingot of low alloy steel.

Abstract: A method of fabricating a nitrided low-alloy steel part, includes a) decarburizing the surface of a low-alloy steel part including at least one alloying element that is both nitride-forming and carbide forming in order to obtain a decarburized part presenting a carbon-depleted surface layer of thickness less than or equal to 1.5 mm, the minimum content of carbon by weight in the carbon-depleted surface layer being less than or equal to 70% of the carbon content by weight in the core of the decarburized part; b) treating the decarburized part with quenching treatment followed by annealing treatment; and c) nitriding the carbon-depleted surface layer in order to obtain a nitrided low-alloy steel part, step c) being performed after step b).

Abstract: A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 ?m/s and to obtain an ingot of low alloy steel.

Abstract: A method of fabricating a nitrided low-alloy steel part, includes a) decarburizing the surface of a low-alloy steel part including at least one alloying element that is both nitride-forming and carbide forming in order to obtain a decarburized part presenting a carbon-depleted surface layer of thickness less than or equal to 1.5 mm, the minimum content of carbon by weight in the carbon-depleted surface layer being less than or equal to 70% of the carbon content by weight in the core of the decarburized part; b) treating the decarburized part with quenching treatment followed by annealing treatment; and c) nitriding the carbon-depleted surface layer in order to obtain a nitrided low-alloy steel part, step c) being performed after step b).

Abstract: A method of treating a steel including, in percentages by weight: 0.2% to 0.33% carbon, 4% to 8% cobalt, 7% to 11% nickel, 0.8% to 3% chromium, 0.5% to 2.5% molybdenum, 0.5% to 5.9% tungsten, 0.05% to 0.2% vanadium, and not more than 0.02% titanium, the balance being constituted by iron and inevitable impurities, the method including subjecting the steel to solutionizing heat treatment at a temperature from 950° C. to 1100° C.; then subjecting the steel to quenching treatment; then placing the steel in a cryogenic enclosure; cooling the inside of the cryogenic chamber in which the steel is present to a treatment temperature less than or equal to ?73° C.; and subjecting the steel to cryogenic treatment while the treatment temperature is maintained inside the enclosure, the time duration between the end of the quenching treatment and the beginning of the cryogenic treatment being less than or equal to 4 hours.

Abstract: A method of fabricating a low alloy steel ingot, the method including a) melting all or part of an electrode by a vacuum arc remelting method, the electrode, before melting, including iron and carbon, the melted portion of the electrode being collected in a crucible, thus forming a melt pool within the crucible; and b) solidifying the melt pool by heat exchange between the melt pool and a cooling fluid, the heat exchange applied serving to impose a mean solidification speed during step b) that is less than or equal to 45 ?m/s and to obtain an ingot of low alloy steel.

Abstract: A method of fabricating a nitrided low-alloy steel part, includes a) decarburizing the surface of a low-alloy steel part including at least one alloying element that is both nitride-forming and carbide forming in order to obtain a decarburized part presenting a carbon-depleted surface layer of thickness less than or equal to 1.5 mm, the minimum content of carbon by weight in the carbon-depleted surface layer being less than or equal to 70% of the carbon content by weight in the core of the decarburized part; b) treating the decarburized part with quenching treatment followed by annealing treatment; and c) nitriding the carbon-depleted surface layer in order to obtain a nitrided low-alloy steel part, step c) being performed after step b).

Abstract: The invention relates to steel for hot tooling, the composition of said steel being made up of the following weight percentages: 0.30%=C=0.39%, 4.00%=Cr=6.00%, traces=Si=0.50%, traces=Mn=0.80%, traces=W=1.45%, traces=Co=2.75%, 0.80%=Ni=2.80%, 1.50%=Mo=2.60% with 1.50%=Mo+0.65W=3.20%, 0.55%=V=0.80%, with 0.65=K=0.65, where K=K2?K1 and K2=0.75×(Ni 0.60), K1=1.43×(V0.40)+0.63×[(Mo+0.65W) 1.20], traces=Al=0.080%, traces=S=0.0040%, traces=P=0.0200%, traces=Ti=0.05%, traces=Zr=0.05%, traces=Nb=0.08%, traces=N=0.040%, 10P+As+5Sb+4Sn=0.21%, traces=O=30 ppm, the remainder being iron and inevitable impurities. The invention also relates to a part produced from said steel, to the method for the production thereof, and to the use of the same.