The chemical composition of the seamless steel pipe contains Cr 15.00 to 18.00% in mass % and satisfies Formulae (1) and (2). Furthermore, in the microstructure, (I) a total volume ratio of ferrite and martensite is 80% or more, with the balance being retained austenite of a volume ratio of 20% or less, (II) the number of intersections NT.sub.L in the L-direction observation field of view is 38 or more and NT.sub.L/NL is 1.80 or more, and further (III) the number of intersections NT.sub.C in the C-direction observation field of view is 30 or more and NT.sub.C/NC is 1.70 or more.

156Al+18Ti+12Nb+11Mn+5V+328.125N+243.75C+12.5S≤12.5  (1)

Ca/S≥≥4.0  (2)

An upholstery spring comprises a steel spring wire made of a microalloyed steel and a color indicator arranged thereon at least in some regions, the microalloyed steel containing between 0.004 to 0.015 wt.-% of one or more alloy elements. The invention further relates to a method for producing an upholstery spring, a mattress or a piece of upholstered furniture having such an upholstery spring.

A rolled wire rod wherein the contents of Ti, N, and S (mass %) are respectively [Ti], [N], and [S], and, if [S]≤0.0010, [Ti] is (4.5×[S]+3.4×[N]) or more and (0.008+3.4×[N]) or less, while if [S]≥0.0010, [Ti] is (4.5×[S]+3.4×[N]) or more and (8.0×[S]+3.4×[N]) or less, the internal structure is a mixed structure of ferrite and pearlite with an area ratio of a ferrite fraction of 40% or more, and a mean area of sulfides present in a range from a surface of the wire rod to a depth position D/8 from the surface of the wire rod is 6 μm.sup.2 or less, wherein D represents a diameter, in mm, in a cross-section of the wire rod at a plane including the axis of the wire rod, and a mean aspect ratio of the sulfides is 5 or less.

The present invention relates to a ferritic stainless steel welding wire, including, in terms of mass %: C: ≤0.050%; Si: ≤1.00%; Mn: 2.50% to 5.00%; P: ≤0.040%; S: ≤0.010%; Cu: ≤0.50%; Ni: 0.01% to 1.00%; Cr: 12.0% to 20.0%; Mo: ≤0.50%; Ti: 0.20% to 2.00%; Nb: 0.10% to 0.80%; Al: 0.020% to 0.200%; Mg: ≤0.020%; O: ≤0.020%; and N: 0.001% to 0.050%, with the balance being Fe and unavoidable impurities, and having a Ni equivalent represented by Equation (1) of 1.0 to 3.0, Ni equivalent=[Ni]+0.5×[Mn]+30×[C]+30×([N]−0.06) Equation (1), in Equation (1), [X] represents a content (mass %) of an element X, and relates to a welded part.

A method for manufacturing a high-strength steel bar can include the steps of: reheating a steel slab at a temperature ranging from 1000° C. to 1100° C., the steel slab including a certain amount of carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), chromium (Cr), copper (Cu), nickel (Ni), molybdenum (Mo), aluminum (Al), vanadium (V), nitrogen (N), antimony (Sb), tin (Sn), and iron (Fe) and other inevitable impurities, The method can further include finish hot-rolling the reheated steel slab at a temperature of 850° C. to 1000° C., and cooling the hot-rolled steel to a martensite transformation start temperature (Ms (° C.)) through a tempcore process.

An austenitic stainless steel is provided which has a chemical composition that consists, by mass %, of: C: 0.015% or less, Si: 1.00% or less, Mn: 2.00% or less, P: 0.05% or less, S: 0.030% or less, Cr: 16.0% or more and less than 22.0%, Ni: 11.0 to 16.0%, Mo: 2.5 to 5.0%, N: 0.07% or more and less than 0.15%, Nb: 0.20 to 0.50%, Al: 0.005 to 0.040%, Sn: 0 to 0.080%, Zn: 0 to 0.0060%, Pb: 0 to 0.030%, and the balance: Fe and impurities, and that satisfies the formula [Mo.sub.SS/Mo≥0.98] (Mo.sub.SS: Mo amount dissolved in the steel).

An NPR non-magnetic steel material for rock bolt and a production method thereof are disclosed. The NPR non-magnetic steel material for rock bolt has a composition, in weight percent, consisting of: C: 0.4-0.7%, Mn: 15-20%, Cr: 1-18%, Si: 0.3-3%, Ca: 0.05-0.15%, Cu: ≤0.03%, Ni: ≤0.02%, S: ≤0.001%, P: ≤0.001%, and the rest being Fe and unavoidable impurity elements. The NPR non-magnetic steel material for rock bolt and the production method thereof effectively solve the problems of steel materials for rock bolt in the prior art such as strong magnetism, low tensile strength and low effective elongation. The NPR non-magnetic steel material for rock bolt has a fully-austenitized structure and is non-magnetic, its yield strength is adjustable in the range of 600-1000 MPa, and its elongation is adjustable in the range of 20-60%.

A wire rod for springs with improved toughness and corrosion fatigue properties is disclosed. The disclosed wire rod comprises by weight percent, carbon (C): 0.4 to 0.7%, silicon (Si): 1.2 to 2.3%, manganese (Mn): 0.2 to 0.8%, chromium (Cr): 0.2 to 0.8%, and a balance of Fe and inevitable impurities, and a grain size is 13.2 μm or less, and a Charpy impact energy value is 38 J/cm.sup.2 or more.

Disclosed are a metal wire, a manufacturing method therefor, and a tire. The metal wire is made by twisting a filament; an outer peripheral surface of the filament is covered with a Cu-M-Zn alloy coating; the outer peripheral surface of the filament is also covered with a Cu—Zn alloy coating; the metal wire is made of at least one filament; an area covered by the Cu-M-Zn alloy coating is 10%-90% of an area of the outer peripheral surface of the filament, and the rest is the Cu—Zn alloy coating; M in the Cu-M-Zn alloy coating is selected from one or two of Co, Ni, Mn, or Mo; the mass fraction of Cu in the Cu-M-Zn alloy coating is 58%-72%, the mass fraction of M in the Cu-M-Zn alloy coating is 0.5%-5%, and the balance in the Cu-M-Zn alloy coating is Zn and inevitable impurities.

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.