Abstract:
A vanadium alloyed steel comprising carbon and vanadium is provided, wherein the steel microstructure comprises coherent interphase precipitates comprising vanadium. Further, a method for producing such a vanadium alloyed steel is provided, comprising providing a starting steel, heating the starting steel to at least partially austenitise the starting steel; holding the temperature at 650°C ± 200°C for about 25 mins or less.
Abstract:
A cold rolled and coated steel sheet having a composition comprising of the following elements, 0.12%≤Carbon≤0.2%, 1.7%≤Manganese≤2.10%, 0.1% ≤Silicon≤ 0.5 %, 0.1%≤Aluminum≤ 0.8%, 0.1% ≤ Chromium ≤ 0.5 %, 0 % ≤ Phosphorus ≤ 0.09 %, 0 % ≤ Sulfur ≤ 0.09 %, 0 % ≤ Nitrogen ≤ 0.09%, Nickel ≤ 3%, Niobium ≤ 0.1%, Titanium ≤0.1%, Calcium≤0.005%, Copper≤2%, Molybdenum≤0.5%, Vanadium≤0.1%, Boron≤0.003%, Cerium≤0.1%, Magnesium ≦ 0.010%, Zirconium≦0.010% the remainder composition being composed of iron and unavoidable impurities caused by processing, the microstructure of said steel sheet comprising in area fraction, 10 to 60% Bainite, 25 to 55% Ferrite, 5% to 15% Residual Austenite wherein carbon content in residual austenite is between 0.7% and 1% and 5% to 18% Martensite, wherein the cumulated amount of Bainite and Ferrite is at least 70%.
Abstract:
A bar or wire product for use in cold forging, characterized in that it comprises a steel having the chemical composition, in mass %: C: 0.1 to 0.65 %, Si: 0.01 to 0.5 %, Mn: 0.2 to 1.7 %, S: 0.001 to 0.15 %, Al: 0.015 to 0.1 %, B: 0.0005 to 0.007%, P: 0.035 % or less, N: 0.01 % or less, O: 0.003 % or less and balance: Fe and inevitable impurities, and it has, in the region from the surface thereof to the depth of the radius thereof x 0.15, a structure wherein ferrite accounts for 10 area % or less and the balance is substantially one or more of martensite, bainite and pearlite, and the average hardness in the region from the depth of the radius thereof x 0.5 to the center thereof is less than that of the surface layer thereof by 20 or more of HV; and a method for producing the bar or wire product. The bar or wire product is excellent in the ductility after spheroidizing and thus allows the prevention of occurrence of cracks in a steel product during cold forging, which has conventionally been a problem in manufacturing structural parts for a machine by cold forging.
Abstract:
A bearing material for cold rolling forming shown in the figure, which consists of high carbon chromium bearing steel ring-like blank, has a hardness adjusted to not higher than HRB102 by spheroidizing annealing or by cold working and annealing after spheroidizing, is free from a fine surface defect at a crack starting point to otherwise be caused by general cutting or grinding, has a surface ferrite decarburized depth of 0.005 to 0.05 mm and has its total decarburized layer depth controlled to 0.15 mm or smaller, whereby providing a steel pipe blank adapted to prevent the development of fine cracks at cold rolling forming (CRF), reduce or omit cutting after CRF and before quenching and enable low-cost CRF work and blanking, permitting an excellent finishing roughness of a product and improving a sealing performance drastically.