A method is used to fabricate a hot-rolled steel having a yield strength greater than 550 MPa and an impact toughness of at least 27 J at a temperature of ?40? F. In one embodiment, the yield strength is greater than 690 MPa. The method includes melting steel to create melted steel. The melted steel is poured into a mold. The metal steel is continuously cast into a steel slab. The steel slab is heated to maintain a predetermined temperature. The steel slab is rolled to reduce the thickness to a predetermined thickness to create a hot-rolled steel sheet.

A carbon separator for a solid polymer fuel cell is provided that includes a core material made of steel, and a carbon layer. The chemical composition of the steel is, by mass %, C: more than 0.02% to 0.12% or less, Si: 0.05 to 1.5%, Al: 0.001 to 1.0%, Mn: 0.01 to 1.0%, P: 0.045% or less, S: 0.01% or less, N: 0.06% or less, V: 0.5% or less, Cr: more than 13.0% to less than 25.0%, Mo: 0 to 2.5%, Ni: 0 to 0.8%, Cu: 0 to 0.8%, REM: 0 to 0.1%, B: 0 to 1.0%, Sn: 0 to 2.5%, In: 0 to 0.1%, and the balance: Fe and impurities. The steel has therein precipitates including M.sub.23C.sub.6 type Cr carbides that are finely precipitated and dispersed. A part of the precipitates protrude from the steel surface.

A carbon separator for a solid polymer fuel cell is provided that includes a core material made of steel, and a carbon layer. The chemical composition of the steel is, by mass %, C: more than 0.02% to 0.12% or less, Si: 0.05 to 1.5%, Al: 0.001 to 1.0%, Mn: 0.01 to 1.0%, P: 0.045% or less, S: 0.01% or less, N: 0.06% or less, V: 0.5% or less, Cr: more than 13.0% to less than 25.0%, Mo: 0 to 2.5%, Ni: 0 to 0.8%, Cu: 0 to 0.8%, REM: 0 to 0.1%, B: 0 to 1.0%, Sn: 0 to 2.5%, In: 0 to 0.1%, and the balance: Fe and impurities. The steel has therein precipitates including M.sub.23C.sub.6 type Cr carbides that are finely precipitated and dispersed. A part of the precipitates protrude from the steel surface.

An object of the present invention is to provide a metal elastic element which is suitable for sensing or the like of a fluid pressure change and exhibits favorable resilience even in the case of receiving a sudden pressure change, and also provide a diaphragm using the same. A metal elastic element of the present invention is composed of a two-phase stainless steel having a -phase and an -phase, wherein the area ratio of the -phase is 40% or less, and the two-phase structure is a marble-like metal structure. In the invention, it is preferred that the element has a fiber texture in which <111> and <110> are preferentially oriented parallel to the thickness direction.

An optimized Gamma-prime () strengthened austenitic transformation induced plasticity (TRIP) steel comprises a composition designed and processed such that the optimized strengthened austenitic TRIP steel meets property objectives comprising a yield strength of 896 MPa (130 ksi), and an austenite stability designed to have M.sub.s.sup.(sh)=40 C., wherein M.sub.s.sup.(sh) is a temperature for shear, and wherein the property objectives are design specifications of the optimized strengthened austenitic TRIP steel. The optimized strengthened austenitic TRIP steel is Blastalloy TRIP 130.

An optimized Gamma-prime () strengthened austenitic transformation induced plasticity (TRIP) steel comprises a composition designed and processed such that the optimized strengthened austenitic TRIP steel meets property objectives comprising a yield strength of 896 MPa (130 ksi), and an austenite stability designed to have M.sub.s.sup.(sh)=40 C., wherein M.sub.s.sup.(sh) is a temperature for shear, and wherein the property objectives are design specifications of the optimized strengthened austenitic TRIP steel. The optimized strengthened austenitic TRIP steel is Blastalloy TRIP 130.

The disclosure relates to a production of a semi-finished product for a manufacturing of objects, particularly tools, from a precipitation-hardenable alloy having a composition in wt. % of Co=15.0 to 30.0, Mo up to 20.0, W up to 25.0, Fe and manufacturing-specific impurities as a remainder. To achieve an economical, highly precise production of objects or tools of the above alloy with reduced effort, it is provided to prevent a formation of ordered structures of the Fe atoms and Co atoms in the matrix of the type (Fe+(29Co))+approximately 1 wt. % Mo of the semi-finished product by a thermal special treatment, to thus improve a workability of the material.

Age hardenable steel is low in hardness after hot forging, providing a machine part with the desired fatigue strength and yield strength by aging treatment, and high in toughness after aging treatment, comprising C: 0.09 to 0.20%, Si: 0.01 to 0.40%, Mn: 1.5 to 2.5%, S: 0.001 to 0.045%, Cr: over 1.00% to 2.00%, Al: 0.001 to 0.060%, V: 0.22 to 0.55%, N: over 0.0080 to 0.0170%, and a balance of Fe and impurities, where an area rate of bainite structures is 80% or more, an effective V ratio (amount of dissolved V/total amount of V) is 0.9 or more, a P and Ti in the impurities is P: 0.03% or less and Ti: less than 0.005%, and the chemical composition is one where the following F1 is 1.00 or less and the F2 is 0.30 or more:

F1=C+0.1Si+0.2Mn+0.15Cr+0.35V

F2=4.5C+Mn+Cr3.5V

A steel sheet for textile machinery parts manufactured at a low cost and is excellent in wear resistance and toughness. The steel sheet for textile machinery parts contains, in mass %, 0.60% or more and 1.25% or less C, 0.50% or less Si, 0.30% or more and 1.20% or less Mn, 0.03% or less P, 0.03% or less S, 0.30% or more and 1.50% or less Cr, and 0.10% or more and 0.50% or less Nb, with the balance being Fe and unavoidable impurities. Furthermore, Nb-containing carbides having a particle size of 0.5 m or more are present in the matrix at a density of 3000/mm.sup.2 or more and 9000/mm.sup.2 or less. Nb-containing carbides' effect of improving wear resistance can be ensured, and deterioration in toughness due to excessive formation of Nb-containing carbides can be prevented. Hence, the resulting wear resistance and toughness are good.

A bearing component composed of a chromium-molybdenum-vanadium alloyed tool steel is produced by a process that includes: (i) performing a first preheating within a temperature range of 600-650 C., (ii) performing a second preheating within a temperature range of 850-900 C., (iii) austenitizing in vacuum at 1000-1180 C. for 20-40 min, (iv) gas quenching at a minimum of 4-5 bar overpressure, and (v) tempering by performing either a double temper at 520-560 C. for 1.5-2.5 hours in each temper, or a triple temper at 520-560 C. for 0.5-1.5 hours in each temper. The steel alloy may be composed (in mass percent) of 1.32-1.45 C, 0.32-0.50 Si, 0.26-0.48 Mn, 4.0-4.85 Cr, 3.35-3.55 Mo, 3.55-3.85 V, 0-0.13 W, 0-0.20 Ni, 0-0.15 Cu, 0-0.8 Co, 0-0.03 P, and 0-0.03 S, the balance being iron and unavoidable impurities. Mo may be replaced with W or vice versa in a replacement ratio Mo:W of 1:2.