Disclosed are a case hardened steel which is suitable as a material for producing mechanical structural parts having high rotating bending fatigue strength and impact fatigue strength at a relatively low cost, and a method of producing the same. The case hardening steel has a chemical composition containing, by mass %, C, Si, Mn, P, S, Cr, Mo, B, Ti, N, and O within a range satisfying a predetermined relationship, and Al in at least a predetermined amount in relation to the B, N, and Ti contents, with the balance being Fe and inevitable impurities, wherein I80 is satisfied, where I represents an area in m.sup.2 of an oxide-based inclusion located at the center of a fish-eye on a fracture surface of the case hardening steel after being subjected to carburizing-quenching and tempering and subsequently to a rotating bending fatigue test.

A sucker rod for use in a subterranean well can include a martensitic stainless steel material with a chromium content in the range of 11.5 to 13%, and a carbon content in the range of 0.08 to 0.15%, and a length of the sucker rod being at least 60 meters. A method of producing a sucker rod for use in a subterranean well can include producing a martensitic stainless steel material of the sucker rod, the material including chromium in the range of 11.5 to 13%, and carbon in the range of 0.08 to 0.15%, heat treating the material, and winding the material for storage.

A sucker rod for use in a subterranean well and a method of producing same, in which the method can include air quenching a martensitic stainless steel material of the sucker rod. An artificial lift system and a method of flowing a fluid from a well, in which the method can include connecting multiple air quenched and tempered sucker rods in a rod string connected to a downhole pump, and operating the downhole pump, thereby flowing the fluid from the well. A sucker rod can include a stainless steel sucker rod composition in which a carbon content is restricted to the range of 0.08% to 0.15%, and in which the sucker rod composition includes up to 0.20% vanadium content, up to 0.10% niobium content, up to 0.05% titanium content, up to 0.99% nickel content and/or up to 1.0% molybdenum content.

A sucker rod steel, a heat treatment process therefor, and a manufacturing method comprising the heat treatment process are provided. The sucker rod steel comprises, in mass percent, the following chemical elements: C: 0.100.20%, Si: 0.400.80%, Mn: 0.200.60%, Mo: 0.360.46%, Cr: 6.157.10%, Al: 0.0150.035%, Nb: 0.020.06%, and N: 0.0080.015%, with the balance being Fe and other inevitable impurities. The microstructure of the sucker rod steel is tempered martensite and nanoscale precipitates. The grain size is higher than grade 10, the tensile strength is 9201320 Mpa, and the AKU2 impact energy is greater than or equal to 180 J.

Disclosed is a martensitic stainless steel material for a hydrogen gas environment, having a composition consisting of: 0.03 mass %?C?1.20 mass %, Si?1.00 mass %, Mn?1.50 mass %, P?0.060 mass %, S?0.250 mass %, Cu?0.50 mass %, 8.0 mass %?Cr?22.0 mass %, Ni?1.00 mass %, and N?0.40 mass %, and optionally at least one selected from the group consisting of: Mo?3.00 mass %, V?1.50 mass %, Nb?1.00 mass %, Pb?0.30 mass %, and B?0.0500 mass %, with the balance being Fe and inevitable impurities; having: a content of a precipitate of 1.50 mass % or more, a crystal grain size number of prior austenite grains of 2.0 or more, a metal structure including a martensite structure, a tensile strength of 1,800 MPa or less, and satisfying D.sub.H2(0.7)/D.sub.air?0.8.

A system for the thermomechanical rolling of long semi-finished steel products includes a first rolling unit; a second rolling unit, arranged downstream of the first rolling unit; a first thermomechanical sizing block, arranged downstream of the second rolling unit; a second cooling device, arranged between the second rolling unit and the first thermomechanical sizing block; a cooling-bed, ring-laying and/or coil-winding device, arranged downstream of the first thermomechanical sizing block; a third cooling device, arranged between the first thermomechanical sizing block and the cooling-bed, ring-laying and/or coil-winding device; and a structure-sensor device, which is arranged between the first thermomechanical sizing block and the cooling-bed, ring-laying and/or coil-winding device, and can be used for determining directly in the ongoing process a martensitic structure, in particular a proportion of martensite in percent by area, in the thermomechanically rolled long semi-finished steel product or in the steel product.

A high manganese content deformed reinforcing bar having an austenite single phase microstructure has excellent bending workability. A deformed reinforcing bar includes a chemical composition containing, in mass %, C: 0.7% or more and 1.2% or less, Si: 1.0% or less, Mn: 9% or more and 15% or less, Cr: 1.0% or less, P: 0.03% or less, and S: 0.05% or less, the balance consisting of Fe and inevitable impurities; and a microstructure comprising an austenite single phase. The ratio of the difference between the maximum and minimum hardness at a periphery of a cross-section perpendicular to the longitudinal direction with respect to a central average hardness is 15% or less. Two or more ribs extend in the longitudinal direction at equal intervals in a cross-sectional circumferential direction. The ratio of the difference between the maximum and minimum width of the ribs to the minimum width is 50% or less.

A pin assembly for use in a planetary gear including a pin including a cylindrical side wall defining a central bore that extends from a first end to a second end of the pin along its longitudinal center axis, an inlet bore, and a first annular groove that extends radially outwardly into the side wall of the pin adjacent the first end. A first cylindrical plate includes a first side wall, a second side wall, and a cylindrical outer wall extending therebetween, the first plate being disposed within the first annular groove of the pin, wherein a width of the first plate in a direction parallel to the longitudinal center axis is less than a width of the first annular groove in the direction parallel to the longitudinal center axis so that the first plate is axially slidable within the first annular groove.

A steel material contains, in mass %, C: 0.30 to 0.50%, Si: 0.40% or less, Mn: 0.10 to 0.60%, P: 0.030% or less, S: 0.030% or less, Cr: 0.90 to 1.80%, Mo: 0.30 to 1.00%, Al: 0.005 to 0.100%, and N: 0.003 to 0.030%, with the balance comprising Fe and impurities. When a Cr concentration in an extraction residue obtained by electrolyzing and removing a region from a surface of the steel material to a depth position of 100?20 ?m by performing a preliminary constant current electrolysis and thereafter further electrolyzing a region from a surface of the steel material to a depth position of 100?20 ?m by performing a main constant current electrolysis is defined as [Cr] (mass %), and a Mo concentration in the extraction residue is defined as [Mo] (mass %), the steel material satisfies Formula (1).

[00001]$\begin{array}{cc}10.?\left[\mathrm{Cr}\right]+\left[\mathrm{Mo}\right]?30.& \left(1\right)\end{array}$

Disclosed is a non-heat treated wire rod, comprising, as percentage by weight: C: 0.3-0.4%; Si: 0.05-0.3%; Mn: 0.8-1.8%; Cr: 0.5% or less; P: 0.02% or less; S: 0.02% or less; sol.Al: 0.01-0.05%; N: 0.01% or less; O: 0.0001-0.003%; at least one of Nb: 0.005-0.03% and V: 0.05-0.3%; and the balance being Fe and unavoidable impurities, wherein the non-heat treated wire rod includes ferrite and pearlite microstructures, and wherein the phase fraction of the pearlite satisfies the following relational expressions 1 and 2, and the average lamellar spacing of the pearlite satisfies the following relational expressions 3 and 4.

VP.sub.2/VP.sub.11.4 [Relational expression 1]

50(15VP.sub.1+VP.sub.2)/1670 [Relational expression 2]

DL.sub.1/DL.sub.21.4 [Relational expression 3]

0.1(15DL.sub.1+DL.sub.2)/160.3 [Relational expression 4]