Patent classifications
C21D1/185
Method for producing a press-hardened laser welded steel part and press-hardened laser welded steel part
A method for producing a part includes providing a first and a second precoated sheet (1,2), butt welding the first and second precoated sheets (1) to obtain a blank (15), and heating the blank (15) to a heat treatment temperature at least 10 C. lower than the full austenitization temperature of the weld joint (22) and at least 15 C. higher than a minimum temperature T
METHOD OF SHAPING AN ARTICLE FROM A ZINC OR ZINC ALLOY COATED STEEL BLANK
A method of shaping an article from a zinc or zinc alloy coated steel blank, including the steps of: a) providing a blank of the zinc or zinc alloy coated steel; b) reheating of the blank obtained in step a) to a reheating temperature T.sub.RH in the range Ac3-200 C. of the steel; c) soaking the blank for a time up to 3 minutes at the reheating temperature T.sub.RH; d) shaping the article in a press; and e) cooling the article.
The steel includes (in wt. %) C: 0.01-0.2; Mn: 3.1-9.0; Al: 0.5-3.0; and optionally further alloying elements selected from Si, Cr, V, Nb, Ti and Mo; inevitable impurities and the balance is Fe.
METHOD FOR PRODUCING MACHINE COMPONENT
A method for producing a machine component excellent in pitting resistance characteristics and toughness includes a carburizing step, performed on a steel material containing 0.13-0.30% C and 0.90-2.00% Cr in mass % and at least one of Si, Mn, Ni, Mo, Nb, V, Ti, B, Al, and N, balance Fe and unavoidable impurities; heating the material to 850-1030 C. to attain carbon concentration in a surface of 0.8-1.5%; cooling the material at an average rate of 5 C./sec or lower from a temperature higher than the A.sub.cm point of a surface layer to a cooling end temperature that is at least 50 C. lower than the A.sub.1 point to cause the surface layer to have a pearlite or bainite structure with dispersion; spheroidizing annealing at a temperature not higher than the A.sub.cm point at the surface layer; heating the material to not higher than the A.sub.cm point at the surface layer; and performing tempering.
STEEL FOR HOT STAMPING, HOT STAMPING PROCESS AND HOT STAMPED COMPONENT
The present invention presents a steel for hot stamping, a hot stamping process and a hot stamped component. The steel for hot stamping in weight percentage contains C: 0.2-0.4%, Si: 0-0.8%, Al: 0-1.0%, B: 0-0.005%, Mn: 0.5-3.0%, Mo: 0-1%, Cr: 0-2%, Ni: 0-5%, V: 0-0.4%, Nb: 0-0.2%, Ti: 0.01%, and impurity elements such as P, S, N unavoidable during smelting, wherein 29*Mo+16*Mn+14*Cr+5.3*Ni30% is satisfied when B0.0005%, and 0.4-1.0% Al is contained when 0.0005%<B0.005%.
RAW MATERIAL FOR COLD-ROLLED STAINLESS STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME
A raw material for a steel sheet, the raw material being suitable for manufacturing a cold-rolled ferritic stainless steel sheet having excellent corrosion resistance, formability, and ridging resistance, and a manufacturing method therefor are provided.
A raw material for a cold-rolled stainless steel sheet has a chemical composition containing, in terms of mass %, C: 0.005 to 0.030%, Si: 0.05 to 1.00%, Mn: 0.05 to 1.00%, P: 0.040% or less, S: 0.030% or less, Al: 0.001 to 0.150%, Cr: 10.8 to 14.4%, Ni: 0.01 to 2.50%, and N: 0.005 to 0.060%, with the balance being Fe and incidental impurities, in which the raw material has a structure containing 10 to 90% of a martensite phase in terms of area ratio with the balance being a ferrite phase.
ULTRA-HIGH-STRENGTH HOT-ROLLED STEEL SHEET, STEEL PIPE, MEMBER, AND MANUFACTURING METHODS THEREFOR
A preferable aspect of the present invention provides: an ultra-high-strength hot-rolled steel sheet containing, by weight, one or two of 0.40-0.60% of C, 0.7-1.5% of Mn, 0.3% or less (excluding 0%) of Si, 0.03% or less (including 0%) of P, 0.004% or less (including 0%) of S, 0.04% or less (excluding 0%) of Al, 0.3% or less (excluding 0%) of Cr, 0.3% or less (excluding 0%) of Mo, 0.9-1.5% of Ni, and 0.9-1.5% of Cu, 1.1% or more of Cu+Ni, 0.04% or less (excluding 0%) of Ti, 0.005% or less (excluding 0%) of B, 0.006% or less (excluding 0%) of N, and the balance Fe and other impurities, the alloy elements satisfying relational formulas 1 and 2 below, wherein a microstructure of the hot-rolled steel sheet comprises, by volume, 7% or more of ferrite and 93% or less of perlite; a steel pipe and a member each using the same; and manufacturing methods therefor. [Relational formula 1] (Mn/Si) #3 (weight ratio) [Relational formula 2] (Ni/Si) #1 (weight ratio)
HOT-PRESSED MEMBER AND METHOD FOR MANUFACTURING SAME, AND COLD-ROLLED STEEL SHEET FOR HOT PRESSING AND METHOD FOR MANUFACTURING SAME
Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, excellent resistance to resistance welding cracking, and excellent delayed fracture resistance after resistance welding by having a specific chemical composition, and a microstructure such that a prior austenite average grain size is 7 m or less, a volume fraction of martensite is 90% or more, and at least 5 Nb-based precipitates having a grain size of less than 0.08 m are present on average per 100 m.sup.2 of a cross section parallel to a thickness direction of the member within a range of 100 m in the thickness direction from a surface of the member, and such that a Ni diffusion region having a thickness of 0.5 m or more is present in a surface layer of the member.
STEEL SHEET
A steel sheet includes, as a chemical composition, by mass %: C: 0.05% to 0.30%; Si: 0.2% to 2.0%; Mn: 2.0% to 4.0%; Al: 0.001% to 2.000%; P: 0.100% or less; S: 0.010% or less; N: 0.010% or less; Ti: 0% to 0.100%; Nb: 0% to 0.100%; V: 0% to 0.100%; Cu: 0% to 1.00%; Ni: 0% to 1.00%; Mo: 0% to 1.00%; Cr: 0% to 1.00%; W: 0% to 0.005%; Ca: 0% to 0.005%; Mg: 0% to 0.005%; a rare earth element (REM): 0% to 0.010%; B: 0% to 0.0030%; and a remainder of Fe and impurities, in which a metallographic structure contains, by area ratio, 95% or more of a hard structure and 0% to 5% of residual austenite, by mass % in a cross section in a thickness direction, C1/C2 which is a ratio of an upper limit C1 of a Mn content to a lower limit C2 of the Mn content is 1.5 or less, and a bake-hardening amount BH is 150 MPa or less.
HIGH ELONGATION PRESS HARDENED STEEL AND MANUFACTURE OF THE SAME
The residual ductility of currently available press hardened steel is approximately six percent. This characteristic of the material is primarily due to the fully martensitic microstructure in the hot stamped condition. The present alloys and processing improve the residual ductility of steels for use in press hardening applications. A series of specialized heat treatments were applied to a variety of new alloys to obtain higher residual ductility and a significant volume fraction of retained austenite in the as-hot stamped microstructure.
Hot Rolled Precipitation Strengthened and Grain Refined High Strength Dual Phase Steel Sheet Possessing 600 MPa Minimum Tensile Strength and a Process Thereof
A process for producing dual phase steel sheet including steps of making a liquid steel having a chemical composition in wt % of C: 0.03-0.12. Mn: 0.8-1.5. Si: <0.1, Cr: 0.3-0.7, S: 0.008 maximum, P: 0.025 maximum, Al: 0.01 to 0.1, N: 0.007 maximum. Nb: 0.005-0.035. and V: 0.06 maximum, remainder Fe; continuous casting the liquid steel into a slab; hot rolling the slab into a hot rolled sheet at finish rolling temperature (FRT) 84030 C.; cooling the hot rolled sheet on the run out table at a cooling rate 40 70 C./s to an intermediate temperature (Tint) of 720 C.Tint650 C.; natural cooling the hot rolled sheet for a duration of 5-7 seconds and rapidly cooling the hot rolled sheet to transform remaining carbon enriched austenite to martensite, at cooling rate of 40-70 C./s to a coiling temperature below 400 C.