Cold-rolled 1300MPa-stage martensitic steel and production method thereof

Abstract

The invention discloses cold-rolled 1300MPa-stage martensitic steel and a production method thereof. The cold-rolled 1300MPa-stage martensitic steel comprises 0.19%-0.25% of C, 1.0%-1.5% of Si, 1.8%-2.5% of Mn, 0.02%-0.07% of Al, not larger than 0.02% of P, not larger than 0.005% of S, not larger than 0.005% of N and the balance Fe and inevitable impurities. The heating temperature of a plate blank ranges from 1230 DEG C to 1280 DEG C, and heat preservation is carried out by 180 min or above; the start rolling temperature of hot rolling is larger than 1100 DEG C, and the finish rolling temperature ranges from 900 DEG C to 1000 DEG C; the coiling temperature ranges from 650 DEG C to 700 DEG C; the cold rolling reduction rate is controlled to range from 40% to 50%; and the heating temperature ranges from 839 DEG C to 880 DEG C, the heat preservation time ranges from 90 s to 120 s, water quenching is carried out, the water entering temperature ranges from 700 DEG C to 750 DEG C, the cooling speed ranges from 300 DEG C / s to 500 DEG C / s, tempering is carried out, the tempering temperature ranges from 300 DEG C to 350 DEG C, the aging time ranges from 370 s to 400 s, and then air coolingis carried out to achieve room temperature.

Description

technical field [0001] The invention belongs to the field of cold-rolled automobile steel manufacturing, and relates to an economical cold-rolled martensitic steel plate with a tensile strength greater than 1300 MPa and a production method thereof. Background technique [0002] In recent years, with the rapid development of automobile lightweight trend, the application of advanced high-strength steel products and advanced forming technology in the automobile industry has increased significantly. Martensitic steel (MS—Martensitic Steel) is the steel with the highest strength level among commercial high-strength steel plates. It is mainly transformed into lath martensitic structure through rapid quenching at high temperature. rolling to achieve. The high strength of martensite is due to the high density of dislocations, fine twins, carbon segregation, and interstitial solid solution of the squareness of martensite. The morphology of low-carbon martensite is basically lath, a...

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Problems solved by technology

In the alloy composition, although it fully considers the role of cheap trace elements and reduces the amount of rare alloy elements, it still adds alloy elements such as Cr, Ni, Ti, Nb to varying degrees; the preparation methods include smelting, casting, forging or Rolling, water quenching, tempering, and electroslag continuous casting and remelting after casting, serious environmental pollution and large cost increase

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