A kind of iron-zinc coated steel plate with a yield strength of 250mpa and its production method

Abstract

An iron-zinc-plated steel plate with the yield strength of the 250-MPa level comprises, by weight percentage, 0.041-0.06% of C, 0.01-0.03% of Si, 0.34-0.50% of Mn, not larger than 0.02% of P, not larger than 0.015% of S, 0.015-0.05% of Als and not larger than 0.005% of N. A production method of the iron-zinc-plated steel plate with the yield strength of the 250-MPa level comprises the production steps that continuous hot dip galvanizing is conducted on the cold-rolled steel plate; the steel plate is conveyed to a zinc-iron diffusion treatment heating furnace under the heat preservation means; the zinc-plated steel plate is subjected to zinc-iron diffusion treatment at high temperature firstly and thereafter at low temperature; and the steel plate is naturally cooled to the room temperature for standby application. According to the iron-zinc-plated steel plate, on the premise of guaranteeing the use mechanics of the steel plate, the surface of a galvannealed coating is compact in structure and free of obvious micro-crack defects, zinc-iron grains on the surface of the coating are wee and evenly distributed in size, the coating is firmly combined with a steel base plate, and the pulverization and falling-off phenomena of the coating are not likely to happen in the stamping forming process.

Description

technical field [0001] The invention relates to a galvanized steel plate and a production method thereof, in particular to an iron-zinc coated steel plate with a yield strength of 250 MPa and a production method thereof, and is suitable for a steel plate with a thickness of 0.7-1.2 mm. Background technique [0002] Zinc-iron coated steel sheet (GA) has excellent corrosion resistance, paintability, weldability and anti-gravel performance, and is widely used in automobile panels. However, zinc slag and zinc ash are prone to appear on the surface of the coating, and the iron content and phase structure of the coating cross-section are unevenly distributed. Defects such as shedding and pulverization of the coating are prone to occur during stamping and forming, which will affect the surface quality of stamping parts and production molds. Negative Effects. [0003] After patent search, a production method of non-powdering thick-gauge zinc-iron alloyed plate was found. The strip ...

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Problems solved by technology

If a fully enclosed alloying furnace is used, the one-step heating method can be used, but the investment of this equipment is high, the equipment is complicated, and the cost of maintenance and accessories is also high

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