Aluminum-plated steel sheet for hot pressing with rapid heating, process for producing same, and method of hot-pressing same with rapid heating

Abstract

An aluminum-plated steel sheet for hot pressing is provided which is free from the conventional problem that an aluminum-plated steel sheet, when applied to hot pressing, suffers aluminum melting during preheating for the hot pressing. The steel sheet is further free from the problem concerning delayed fracture caused by residual hydrogen. Also provided are: a process for producing the aluminum-plated steel sheet; and a method of hot pressing with rapid heating in which the aluminum-plated steel sheet is used. The aluminum-plated steel sheet for hot pressing is produced by annealing an aluminum-plated steel sheet in a coiled state in an annealing box furnace under holding-time and temperature conditions which are within the range shown in Fig 5, whereby the aluminum deposit is alloyed with the steel sheet. The method of hot pressing with rapid heating is characterized in that a blank cut out of the aluminum-plated steel sheet for hot pressing is preheated at a heating rate of 40 DEG C / sec or higher on the average so that the time period over which the blank is exposed to an environment of 700 DEG C or higher is 20 seconds or shorter, and the preheated blank is hot-pressed.

Description

technical field

[0001] The present invention relates to an aluminized steel sheet for rapid heating and hot pressing, a method for producing the same, and a method for rapid heating and hot pressing using the same , and excellent productivity. Background technique

[0002] In recent years, applications of steel sheets for automobiles (for example, automobile pillars, door impact beams, bumper beams, etc.) have been expected to have both high strength and high formability. As one of the steel sheets satisfying the demand, there is TRIP (Transformation Induced Plasticity) steel utilizing martensitic transformation of retained austenite. From the above-mentioned TRIP steel, a high-strength steel sheet having excellent formability and a strength on the order of 1000 MPa can be obtained, whereby the above-mentioned automobile parts can be manufactured. However, it is currently difficult to ensure formability when using ultra-high-strength steel with higher strength, for example...

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