In the method of producing a martensitic stainless steel strip, a quenching furnace of a quenching process includes at least a temperature raising unit and a holding unit. When a predetermined quenching temperature is set as T (° C.), the temperature raising unit is set to be within a temperature range of 0.7T (° C.) or higher and lower than T (° C.), and a set heating temperature on an exit side of the steel strip is set to be higher than a set heating temperature on an entry side of the steel strip when the steel strip passes through the temperature raising unit. The holding unit is set to the quenching temperature T (° C.). A time spent in the furnace by the steel strip in the temperature raising unit is equal to or longer than a time spent in the furnace by the steel strip in the holding unit.

A method of hardening a surface of a ferro-alloy object, the method comprising at least partially gasifying a carbon-containing polymer to form a hardening material source; and exposing the object to the hardening material source, such that the hardening material source and the surface of the object react, thereby hardening the surface of the object.

Various methods are provided to produce welded structures resistant to hydrogen induced cracking (HIC), improve wear resistance, reduce manufacturing steps including pre/post weld treatments, and improving corrosion resistance. Exemplary methods include using exothermic reactive powder mixtures on as-welded hot surface(s) during weld cooling which generate rapid exothermic reaction melting and hydrogen removal which results in reduction of hydrogen, creation of a wear/corrosion prevention or reduction layer, and a reduction of residual stresses effect in the weld initially formed in initial welding. Alternative embodiments can also employ post cooling re-heating and application of one or more alternative methods using exothermic reactive powders.

A press-hardened steel is provided. The press-hardened steel has an alloy matrix including from about 0.01 wt. % to about 0.35 wt. % carbon, from about 1 wt. % to about 9 wt. % chromium, from about 0.5 wt. % to about 2 wt. % silicon, and a balance of iron. The alloy matrix is greater than or equal to about 95 vol. % martensite. A first layer is disposed directly on the alloy matrix. The first layer is continuous, has a thickness of greater than or equal to about 0.01 m to less than or equal to about 10 m, and includes an oxide enriched with chromium and silicon. A second layer is disposed directly on the first layer, and includes an oxide enriched with Fe. Methods of preparing the press-hardened steel are also provided.

A method of manufacturing a separator includes subjecting a metal thin sheet material to be transported to stepwise forming working at an identical location by a plurality of press machines having different working shapes and arranged sequentially from an upstream side to a downstream side in a transport direction of the metal thin sheet material to form a flow passage groove. The thin sheet material is subjected to annealing treatment in at least one space of spaces between the press machines arranged adjacent to each other in the transport direction of the thin sheet material.

A non-scaling heat-treatable steel with particular suitability for producing hardened or die-hardened components is disclosed, characterized by the following chemical composition in % by weight: C 0.04-0.50; Mn 0.5-6.0; Al 0.5-3.0; Si 0.05-3.0; Cr 0.05-3.0; Ni less than 3.0; Cu less than 3.0; Ti 0.0104-0.050; B 0.0015-40.0040; P less than 0.10; S less than 0.05; N less than 0.020; remainder iron and unavoidable impurities. Further disclosed is a method for producing a non-scaling hardened component from the steel and a method for producing a hot strip from a steel.

Resistance annealing furnace to anneal at least one metal or metal alloy wire, strand, string, wire rod or strip, the annealing furnace having at least two electric axles provided with respective electric contact rings for conveying the metal or metal alloy wire, strand, string, wire rod or strip, and a DC voltage generator, which can be supplied by an AC voltage (Uac) to generate an annealing voltage (Uann) applied between the two electric axles so as to produce an electric current in the portion of the metal or metal alloy wire, strand, string, wire rod or strip extending between the two electric axles, which provokes an annealing due to the Joule effect. At least one of the electric contact rings is made of a non-metal electric conductor material, for example graphite.

Provided is a martensite-based stainless steel component that has a nitride layer on a surface of a martensite-based stainless steel with a constituent composition including, in percent by mass, 0.25 to 0.45% of C, 1.0% or less of Si, 0.1 to 1.5% of Mn, 12.0 to 15.0% of Cr, and 0.5 to 3.0% of Mo, with a remainder being Fe and impurities, wherein hardness at a position of a depth of 0.1 mm from a surface of the martensite-based stainless steel component is 650 HV or more, and a number density of carbide with an equivalent circle diameter of 1 m or more is 100 particles/10000 m.sup.2 in a sectional structure at the position of the depth of 0.1 mm from the surface of the martensite-based stainless steel component. Also, a method for manufacturing the martensite-based stainless steel component is provided.

An ultra-high-strength air-hardenable multiphase steel having minimal tensile strengths in a non air hardened state of 950 MPa and excellent processing properties, includes the following elements in % by weight: C0.075 to 0.115; Si0.400 to 0.500; Mn1,900 to 2,350; Cr0.200 to 0.500; Al0.005 to 0.060; N0.0020 to 0.0120; S0.0030; Nb0.005 to 0.060; Ti0.005 to 0.060; B0.0005 to 0.0030; Mo0.200 to 0.300; Ca0.0005 to 0.0060; Cu0.050; Ni0.050; remainder iron, including usual steel accompanying smelting related impurities, wherein for a widest possible process window during continuous annealing of hot rolled or cold rolled strips made from said steel a sum content of M+Si+Cr in said steel is a function of a thickness of the steel strips according to the following relationship: for strip thicknesses of up to 1.00 mm the sum content of M+Si+Cr is 2.800 and 3.000%, for strip thicknesses of over 1.00 to 2.00 mm the sum of Mn+Si+Cr is 2.850 and 3.100%, and for strip thicknesses of over 2.00 mm the sum of Mn+Si+Cr is 2.900 and 3.200%.

A carburization method for steel is contemplated, with austenitic stainless steel showing particular promise. The surface is first passivated with an acidic solution and then subjected to low temperature (between 350 to 550 C. or between 650 to 1,000 F.) carburization in the presence of a concentrated carbon solution (e.g., carbon monoxide, hydrogen gas, and nitrogen gas), followed by a repeated cycle of passivation and carburization under identical conditions but for a comparatively shorter period of time relative to the first cycle. The carburized surface is allowed to cool and cleaned, after which the resulting surface is shown to have ultrahigh tensile strength, increased interatomic bonding strength, and lowered electrical and thermal conductivity. To the extent this method can be employed to completely saturate and penetrate the workpiece (e.g., a foil), the resultant material and article are formed entirely from a novel composition.