A kind of dual-phase steel plate and its manufacturing method

Abstract

The invention provides a double-phase steel plate which comprises 0.07-0.098 of C, 0.1-0.4 of Si, 1.95-2.2 of Mn, 0.3-0.6 of Cr, less than or equal to 0.015 of P, less than or equal to 0.004 of S, less than or equal to 0.005 of N, 0.015-0.04 of Nb, 0.015-0.04 of Ti, 0.015-0.045 of Al, and 0.002-0.004 of B or 0.2-0.4 or Mo, wherein Pcm equals to C+Si / 30+Mn / 20+2P+4S which is less than or equals to 0.24; and the double-phase steel plate also comprises the balance of Fe and unavoidable impurities. The invention also provides a manufacturing method of the double-phase steel plate. The high-strength uniform-performance double-phase steel plate can be obtained by the proper composition design and manufacturing technology, and the manufacturing requirements on parts of a high-strength automobile body can be better met.

Description

technical field [0001] The invention relates to a dual-phase steel plate and a manufacturing method thereof, in particular to a performance-balanced cold-rolled 980MPa dual-phase steel plate and a manufacturing method thereof. Performance-balanced dual-phase steel refers to cold-rolled high-strength dual-phase strip steel with low carbon equivalent, high elongation and hole expansion rate. Background technique [0002] The automotive industry requires the use of higher strength steel plates for weight reduction. Among them, ultra-high-strength dual-phase steel with a tensile strength of 980Mpa and above has increasingly become the first choice for the automobile manufacturing industry, because steel of this strength level can effectively reduce the weight of the automobile body and improve safety. In the automobile manufacturing process, high-strength steel plates not only require good elongation, but also have high requirements for local formability, that is, high requirem...

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Problems solved by technology

[0010] The above patents involving 980Mpa dual-phase steel, although some involve higher hole expansion rate, all adopt high carbon content and high Si content, which is not conducive to weldability, surface quality and phosphating performance

In addition, some high-Si steels have a high hole expansion rate, but the yield ratio is high, and the stamping performance decreases

Although it has advantages in the manufacture of parts with higher single requirements for hole expansion rate, it cannot adapt to the manufacture of parts with higher requirements for drawing and hole expansion, and most of the safety structural parts of automobile bodies belong to this category

The design of the above-mentioned invention failed to take into account the balance of carbon equivalent, drawing performance and hole expansion rate, and also failed to take into account good surface and phosphating performance

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