A thin-gauge hot-rolled dual-phase steel with a tensile strength of 600mpa and its manufacturing method

Abstract

A thin specification hot-rolled dual-phase steel with a tensile strength of 600MPa and a manufacturing method thereof, belonging to the field of metallurgical technology; the chemical composition of the dual-phase steel in mass percentage is: C: 0.04~0.065%, Si: 0.05~0.14%, Mn : 0.85~1.05%, Cr: 0.20~0.30%, S: ≤0.015%, P: ≤0.015%, Als: 0.02~0.04%, the balance is Fe and inevitable impurities. Manufacturing method of dual-phase steel: Manufacturing method of dual-phase steel: 1) Pouring molten steel into ingot; 2) Direct rolling of the ingot; 3) Three-stage cooling of water-air cooling-water cooling for the strip; this method The invention adopts the direct rolling process of cast slabs to reduce the heating process before rolling, give full play to the role of large deformation in refining grains, reduce the usage of manganese, chromium and silicon, without adding other precious micro-alloy elements, and significantly reduce the production cost. The production efficiency is reduced, the production efficiency is improved, the steel plate has a uniform structure and good surface quality, realizing the use of heat instead of cold in dual-phase steel.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, and in particular relates to a thin-gauge hot-rolled dual-phase steel with a tensile strength of 600 MPa and a manufacturing method thereof. Background technique [0002] In order to achieve vehicle weight reduction and improve fuel efficiency, the application of high-strength steel sheets in the field of automobile manufacturing is gradually increasing. Among these high-strength steel plates, dual-phase steel has a good combination of strength and toughness, and a lower yield ratio (R p0.2 / R m ), high elongation and work hardening rate, and continuous yielding, stamping components are easy to form, have small springback, and stamping die wear is also small, which can meet the application conditions of various parts of automobiles, among which the tensile strength is 540 ~ 600MPa Hot-rolled dual-phase steel is the most widely used, but the thickness of this type of steel plate is mostly abo...

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Problems solved by technology

[0003] Patent CN200610047553.8 discloses a medium-thin slab continuous casting and rolling dual-phase steel plate with a tensile strength of 600MPa and its manufacturing method. 0.10-0.80% chromium (Cr), can also add an appropriate amount of molybdenum (Mo), niobium (Nb) and titanium (Ti), the cost is relatively high, due to the high content of silicon (Si) (0.20-1.14%), it is easy to The formation of red oxide scales leads to poor surface quality of the steel plate. At the same time, the casting slab needs to be heated before rolling, and the production efficiency is low; the patent CN200610098392.5 discloses a thin slab continuous casting and rolling production of hot-rolled double slabs with a tensile strength above 600MPa. Compared with the steel process, the thickness of the steel plate is 4-8mm, and 1.5-2.0% of manganese (Mn), 0.4-0.6% of chromium (Cr) and 0.02-0.14% of vanadium (V) are added in the composition design, and the production cost is relatively low. High silicon (Si) content of 0.6 to 1.0%, easy to form red oxide scales, resulting in poor surface quality of the steel plate, while the billet needs to be heated before rolling, and the production efficiency is low; patent CN200610045846.2 discloses a tensile Strength 600MPa dual-phase steel plate and its manufacturing method, the thickness of the steel plate is 2.5-6.0mm, and 1.30-1.60% manganese (Mn) is added in its composition design, the cost is relatively high, and the silicon (Si) content is 0.20-0.40%, but rolling The casting slab still needs to be heated before making, and the production efficiency is low; the patent CN201010212597.8 discloses a method for manufacturing hot-rolled dual-phase steel with a tensile strength of 590MPa based on the CSP process. Add 1.20-1.55% manganese (Mn), silicon (Si) content is 0.45-0.55%, easy to form red oxide scale, resulting in poor surface quality of the steel plate, and at the same time, the cast slab needs to be heated before rolling, and the production efficiency is low; patent CN200680051836.8 discloses a hot-rolled dual-phase steel strip with characteristics of cold-rolled strip, the thickness of the steel plate is 1.0-8.0mm, and 1.0-2.0% manganese (Mn) and ≤0.30% nickel are added in the composition design (Ni) and ≤0.03% molybdenum (Mo), the cost is high, and the silicon (Si) content is ≤0.80%, which is easy to form red oxide scale, resulting in poor surface quality of the steel plate. Insulation in a furnace with an internal mandrel, less productive

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