The process of making a steel component from a hot-rolled steel strip by pressing, comprises cutting the sheet to obtain a sheet blank, subjecting the coated sheet blank to high temperature to form a component in heat, carrying out pressing of the sheet blank to obtain the component, preparing an intermetallic alloy compound on surface before or after pressing, providing protection against corrosion and decarburization of steel, and cooling the formed component to provide the mechanical characteristics of high hardness to the steel and high surface hardness to the coating. The process of making a steel component from a hot-rolled steel strip by pressing, comprises cutting the sheet to obtain a sheet blank, subjecting the coated sheet blank to high temperature to form a component in heat, carrying out pressing of the sheet blank to obtain the component, preparing an intermetallic alloy compound on surface before or after pressing, providing protection against corrosion and decarburization of steel, cooling the formed component to provide the mechanical characteristics of high hardness to the steel and high surface hardness to the coating, and removing by cutting the excess sheet necessary for the pressing operation. The intermetallic compound provides a lubrication function. The coated sheet is subjected to a high temperature of greater than 700[deg] C prior to heat treatment. The component obtained by pressing is cooled for undergoing hardening at a speed greater than the hardening critical speed.

Method for manufacturing a body featuring very high mechanical properties, forming by drawing from a rolled steel sheet, in particular hot rolled and coated sheet

PURPOSE:To improve the powdering resistance of the title steel sheet by forming, in numerous numbers, the rugged parts, each of which consists of a plateau part and a valley part surrounding the above plateau part and in each of which the relationship between the groove width and depth of the valley part is specified, on the surface of a base steel sheet and then forming a Zn-Fe alloy galvanizing layer on the above steel sheet. CONSTITUTION:The rugged parts, each of which is composed of a nearly circular plateau part 1a and a valley part 2a surrounding the foot of the plateau part 1a, are formed in numerous numbers on the surface of a base steel plate by using a laser dull finish roll, etc. At this time, the depth (d) of the valley part 2a is regulated to 2-10mum, and also the relationship between the groove width (W) of the valley part 2a and the above depth (d) is regulated so that it satisfies 2<W/d<10, and further, the part other than the above-mentioned rugged parts is composed of a flat part 3. Then, Zn-Fe alloy galvanizing is applied to the surface of the above base steel by means of electroplating, etc., which is subjected to heat treatment to undergo the alloying of the galvanizing layer. By this method, the powdering resistance of the alloying galvanized steel sheet can be improved without lowering productivity.

Alloying galvanized steel sheet

PURPOSE:To make zinc-plated surface into alloy, by zinc plating and heat treating a steel hoop which has been dull finished. CONSTITUTION:Steel hoop finished by cold rolling is dull worked to 0.8-2.5murms. Then the steel hoop is brought into a heating furnace, where its surface is cleaned, thereafter the steel hoop is plated with zinc on the surface in a hot dipping bath of zink. The amount of coated molten zinc is controlled to a constant value, and the hoop is heated to a temp. 450-1,000 deg.C to form a layer of Zn-Fe alloy. The plated alloy layer is excllent in weldability and adherability for coating medium.

Kohei Sato

Papers

Alloying method for zinc-plated steel sheet