A method for improving the formability of ultra-low carbon aluminum-killed steel galvanized products

Abstract

The invention discloses a method for improving the forming performance of a super-low-carbon aluminum killed steel galvanized product. The method comprises steps of hot rolling, cold rolling, cover annealing and galvanizing. A casting blank is prepared from the following alloy ingredients in percentage by weight: less than or equal to 0.010 percent of C, 0.15-0.35 percent of Mn, less than or equal to 0.010 percent of S, less than or equal to 0.015 percent of P, less than or equal to 0.030 percent of Si, 300-600ppm of Als, less than or equal to 30ppm of N and the balance of Fe and inevitable impurities. By adopting super-low-carbon steel beneficial to formation and regulating hot rolling, reeling, annealing and other processes, the prepared product is low in cost and excellent in surface quality, has excellent forming performance and aging resistance, and does not need overaging treatment in the galvanizing step.

Description

technical field [0001] The invention relates to the technical field of metallurgy, and relates to a method for improving the formability of an ultra-low-carbon aluminum-killed steel galvanized product. Background technique [0002] In order to improve the product yield and the appearance of stamped parts, for galvanized products, in addition to the surface quality requirements of the zinc layer, the home appliance and automobile industries have strict requirements for stamped galvanized sheets. For example, on the one hand, they must have good mechanical properties, especially It is good stamping performance, which is manifested as high elongation, work hardening index and plastic strain ratio; on the other hand, the material has a certain period of anti-aging characteristics, and it is strictly required to be more than 3 months. In order to meet the different needs of customers, interstitial atom-free steel is mostly used in the market, that is, IF steel, but the production...

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Problems solved by technology

In order to meet the different needs of customers, interstitial atom-free steel is mostly used in the market, that is, IF steel, but the production cost of this steel is high, and the production process is converter steelmaking→RH refining→continuous casting→hot rolling→cold rolling→plating Zinc, in the galvanizing process, the heating temperature, time and flat elongation of the strip have a great influence on the final performance of the product; in industries that do not require high product performance, low-carbon steel can also be used for production, and the process is a converter Steelmaking → LF refining → continuous casting → hot rolling → cold rolling → galvanizing, however, because steel contains interstitial atomic elements, such as C and N, overaging treatment is required in the galvanizing process to obtain excellent aging resistance However, no matter what metallurgical scheme is adopted, in order to fully recrystallize the deformed grains of cold rolling, a high heating temperature is required in the soaking section of galvanizing, generally higher than 800°C, even so, continuous When producing low-carbon steel by galvanizing, due to the fast production speed and short heating time, it is difficult for deformed grains to fully complete the process of recovery, recrystallization and grain growth, resulting in small grain size, high product strength, low elongation, and low yield. Moreover, for galvanizing production lines with no aging treatment section or short aging treatment section, the mechanical properties of low carbon steel finished steel sheets and strips will deteriorate with the prolongation of storage time, For example, the yield strength and tensile strength increase, the elongation after fracture decreases, the formability deteriorates, and forming defects such as tensile strain marks appear.

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