980mpa grade cold-rolled composite phase steel with good hole expansion performance and its preparation method

Abstract

The invention discloses 980MPa-level cold-rolling complex-phase steel with good hole-expanding property and a preparation method thereof and belongs to the technical field of steel. The complex-phasesteel is prepared from the following chemical components in percent by mass: 0.15-0.20% of C, 0.30-0.80% of Si, 1.7-2.3% of Mn, less than or equal to 0.015% of P, less than or equal to 0.008% of S, less than or equal to 0.08 of Al, 0.02-0.08% of Nb, 0.4-0.8% of Cr, 0.02-0.06% of Ti and the balance of Fe and inevitable impurities. Then by a hot-rolling process and a cold-rolling process, in the cold-rolling process, the temperature of acid liquid in acid pickling of strip steel is controlled to be 70-90 DEG C, the total reduction ratio of cold rolling is 56-72%, and the thickness of the strip steel after cold rolling is controlled to be 1.0-2.0mm. The steel plate after cold rolling adopts a continuous annealing process, the soaking temperature is 800-850 DEG C, the ending temperature at a slow cooling stage is 650-720 DEG C, the ending temperature at a rapid cooling stage is 350-480 DEG C, the overaging temperature is 300-450 DEG C, and the temperature at a final cooling stage is 100-180 DEG C. The 980MPa-level cold-rolling complex-phase steel with good hole-expanding property and the preparation method disclosed by the invention have the beneficial effects that a steel plate is ensured to have higher strength and meanwhile have better shaping and anti-flanging properties.

Description

technical field [0001] The invention relates to a composite phase steel, which belongs to the technical field of iron and steel, in particular to a 980MPa grade cold-rolled composite phase steel with good hole expansion performance and a preparation method thereof. Background technique [0002] The automobile industry is a pillar industry in industrially developed countries, and it is also the largest user of steel companies. Under the requirements of energy saving, environmental protection, safety and sustainable development, high-strength and ultra-high-strength steels have become the mainstream of steel for automobile bodies, thus reaching the automotive industry. In order to develop high-strength steel plates for automobiles and promote the lightweight of automobiles, a large number of researches on related automobile lightweight projects have been started in the world in recent years. The common point of their research is to reduce the weight of automobiles. 20% to 40%....

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Problems solved by technology

In the same way, although this application involves the problem of hole expansion rate of multiphase steel, it does not give specific performance parameters, so it is not possible to judge whether the product performance of this application is good or bad.

[0008] Another example is European patent EP2011074251 which discloses "hot-rolled steel plate products made of multi-phase steel and its manufacturing method". Consider hole expansion performance, etc.

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