A process of manufacturing of segment for carbon thrust bearing uses stainless-steel (SS) round bars/sheets/logs of suitable grade as raw material. The SS round bars/sheets/logs undergo cutting operation to cut into SS billets. The billets successively undergo heating and hot forging processes to form segments of desired shapes. Thereafter, the segment is subjected to heat treatment process i.e. stress relieving, hardening and tempering process successively for obtaining consistent and uniform grain structure, mechanical properties and physical properties of segments which are cost-effective in terms of lower maintenance and lower handling efforts. After heat-treatment process, segment undergoes surface-finishing processes i.e. grinding, lapping and polishing successively for obtaining mirror like surface finishing that gives greater anti-friction property and lower co-efficient of friction. The manufacturing process according to present invention yields consistent grain structure, refine, dense and uniform microstructure of segments which imparts optimum strength, ductility, toughness and resistance to impact and fatigue.

Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more and excellent delayed fracture resistance after projection welding by properly adjusting its chemical composition and its microstructure such that at least 5 Ti-based precipitates having a grain size of 0.10 μm or less are present on average per 100 μm.sup.2 of a cross section parallel to a thickness direction of the member within a range of 100 μm in a thickness direction from a surface of the member, a volume fraction of martensite is 95% to 100% within a depth range of 20 μm to 100 μm in the thickness direction from the surface of the member, and at least 10 cementite grains having a grain size of less than 0.20 μm are present on average in a prior austenite grain.

A steel material has a chemical composition which consists of, in mass %, C: 0.15 to 0.30%, Si: 0.02 to 1.00%, Mn: 0.20 to 0.80%, P: 0.020% or less, S: 0.028% or less, Cr: 0.80 to 1.50%, Mo: 0.08 to 0.40%, V: 0.10 to 0.40%, Al: 0.005 to 0.060%, N: 0.0150% or less, O: 0.0030% or less, and the balance: Fe and impurities, and satisfies Formulae (1) and (2), in which, at a cross section parallel to the axial direction of the steel material for a steel piston, the number of Mn sulfides is 100.0 per mm.sup.2 or less, the number of coarse Mn sulfides having an equivalent circular diameter of 3.0 μm or more is in a range of 1.0 to 10.0 per mm.sup.2, and the number of oxides is 15.0 per mm.sup.2 or less.

0.42≤Mo+3V≤1.50  (1)

V/Mo≥0.50  (2)

The invention relates hot work tool steel. The steel comprises the following main components (in wt. %): TABLE-US-00001 C 0.27-0.38 Si 0.10-0.35 Mn 0.2-0.7 Cr 4.5-5.5 Mo 2.05-2.90 V 0.4-0.6 N 0.01-0.12 H ≤0.0004 S ≤0.0015 balance optional elements, iron and impurities.

The invention is intended to provide a martensitic stainless steel seamless pipe for oil country tubular goods having a yield stress of 758 MPa or more, and excellent sulfide stress corrosion cracking resistance. A method for manufacturing such a martensitic stainless steel seamless pipe is also provided. The martensitic stainless steel seamless pipe for oil country tubular goods has a composition that contains, in mass %, C: 0.010% or more, Si: 0.5% or less, Mn: 0.05 to 0.50%, P: 0.030% or less, S: 0.005% or less, Ni: 4.6 to 8.0%, Cr: 10.0 to 14.0%, Mo: 1.0 to 2.7%, Al: 0.1% or less, V: 0.005 to 0.2%, N: 0.1% or less, Ti: 0.010 to 0.054%, Cu: 0.01 to 1.0%, and Co: 0.01 to 1.0%. C, Mn, Cr, Cu, Ni, Mo, W, N, and Ti satisfy the predetermined relations, and the balance is Fe and incidental impurities. The martensitic stainless steel seamless pipe has a yield stress of 758 MPa or more.

Disclosed is an alloy having 7-30 wt. % manganese, 1-15 wt. % nickel, 1-10 wt. % aluminum, 1-8 wt. % copper, 0-15 wt. % chromium, 0-5 wt. % molybdenum, 0-3 wt. % vanadium, 0-3 wt. % titanium, 0-3 wt. % niobium, 0-2 wt. % silicon, 0-1 wt. % carbon, and balance of iron. A majority of the iron is γ-Fe. The alloy has β-NiAl precipitates and Cu-rich precipitates. At least 95 vol. % of the β-NiAl precipitates have a maximum dimension of 500 nm or less. The Cu-rich precipitates are at least 40 at. % copper. The alloy can be made by thermal processing steps without mechanical processing steps.

Disclosed is an alloy having 7-30 wt. % manganese, 1-15 wt. % nickel, 1-10 wt. % aluminum, 1-8 wt. % copper, 0-15 wt. % chromium, 0-5 wt. % molybdenum, 0-3 wt. % vanadium, 0-3 wt. % titanium, 0-3 wt. % niobium, 0-2 wt. % silicon, 0-1 wt. % carbon, and balance of iron. A majority of the iron is γ-Fe. The alloy has β-NiAl precipitates and Cu-rich precipitates. At least 95 vol. % of the β-NiAl precipitates have a maximum dimension of 500 nm or less. The Cu-rich precipitates are at least 40 at. % copper. The alloy can be made by thermal processing steps without mechanical processing steps.

The invention relates to a steel wire suitable for making a spring or medical wire products which remarkably improve the performance of conventional stainless steel wire. The steel comprises (in wt. %): C: 0.02 to 0.15, Si: 0.1 to 0.9, Mn: 0.8 to 1.6, Cr 16 to 20, Ni: 7.5 to 10.5, Mo: ≤3, Al: 0.5 to 2.5, Ti: ≤0.15, N: ≤0.05, optional elements, and impurities, balance Fe, wherein the total amount of Cr and Ni is 25 to 27 wt. %, and wherein the steel has a microstructure including, in volume % (vol. %), martensite: 40 to 90, austenite: 10 to 60, and delta ferrite: ≤5.

A hot rolled steel sheet having a chemical composition consisting of, in mass %, C: 0.020-0.070%, Si: 0.05-1.70%, Mn: 0.60-2.50%, Al: 0.010-1.000%, N: >0-0.0030%, P≤0.050%, S≤0.005%, Ti: 0.015-0.170%, Nb: 0-0.100%, V: 0-0.300%, Cu: 0-2.00%, Ni: 0-2.00%, Cr: 0-2.00%, Mo: 0-1.00%, B: 0-0.0100%, Mg: 0-0.0100%, Ca: 0-0.0100%, REM: 0-0.1000%, Zr: 0-1.000%, Co: 0-1.000%, Zn: 0-1.000%, W: 0-1.000%, Sn: 0-0.050%, the balance: Fe and impurities, a metal microstructure includes, in area %, ferrite: 5-70%, bainite: 30-95%, retained γ≤2%, martensite≤2%, pearlite≤1%, ferrite+bainite≥95%, a number density of the precipitates in ferrite grains is 1.0×10.sup.16−50.0×10.sup.16/cm.sup.3, an average circle-equivalent diameter of the TiN precipitates in the steel sheet is 1.0-10.0 μm, an average of minimum distances between adjacent TiN precipitates is 10.0 μm or more, and a standard deviation of nano hardness is 1.00 GPa or less.

Maraging steel alloys are disclosed. The alloys are produced by microalloying of the maraging steel alloy to form carbides at prior austenite grain boundaries to increase Zener drag. A particular example alloy consists essentially of, by weight, 7.4 to 8.4 percent nickel, 7.6 to 8.6 percent chromium, 8.4 to 9.4 percent cobalt, 1.8 to 2.2 percent molybdenum, 2 to 2.6 percent tungsten, 1.6 to 2 percent aluminium, 0.05 to 0.08 percent carbon, a carbide former selected from the group consisting of: niobium at a concentration of 0.25 to 0.28 percent; titanium, at a concentration of 0.2 to 0.28 percent; and vanadium, at a concentration of 0.21 to 0.4 percent; the balance being iron and incidental impurities.