A production method for 270MPa grade hot-dip galvanized deep-drawing steel strip

By employing hot-dip galvanizing and Ti microalloying technology, the problems of poor formability and high cost of thick hot-dip galvanized steel sheets have been solved, resulting in the production of high-plasticity, corrosion-resistant 270MPa-grade hot-dip galvanized deep-drawing steel strips that meet the needs of automobile manufacturing.

CN119614826BActive Publication Date: 2026-01-30PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
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Patent Information

Application Number
CN202411836397.8
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2024-12-13
Publication Date
2026-01-30
Estimated Expiration
2044-12-13

AI Technical Summary

Technical Problem

Existing technologies cannot produce thick hot-dip galvanized steel sheets with a yield strength of 270 MPa, and the traditional pickling-rolling-hot-dip galvanizing process cannot meet the requirements for thick specifications, thick coatings, and low cost, resulting in low plasticity and poor formability of the finished product.

Method used

The hot-dip galvanizing process is adopted, which involves smelting, LF refining, RH treatment, continuous casting, hot rolling, pickling and hot-dip galvanizing. The chemical composition and hot rolling process conditions are controlled. Combined with Ti microalloying and refinement of hot-rolled microstructure, the cold rolling process is omitted. The refinement of ferrite grains and TiC and Ti(C,N) particles is used to inhibit the growth of annealed grains.

Benefits of technology

We produce 270MPa grade hot-dip galvanized deep-drawing steel strips with excellent mechanical properties, improved plasticity, good formability, excellent corrosion resistance, and lower cost, meeting the needs of the automotive manufacturing industry.

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Abstract

This invention provides a method for producing 270MPa grade hot-dip galvanized deep-drawing steel strip. The method controls the chemical composition, the hot rolling process (including soaking temperature, final rolling temperature, and coiling temperature), and the hot-dip galvanizing process (including annealing temperature, galvanizing temperature, finishing, and tension leveling). This results in hot-dip galvanized steel strip with excellent mechanical properties (Rp0.2 = 185–255 MPa, Rm ≥ 270 MPa, A50mm ≥ 42%, n90 ≥ 0.17). It effectively overcomes the problems of mixed crystals and performance deterioration in the pickling-hot-dip galvanizing technology during annealing due to lack of deformation recovery, recrystallization, and grain growth. The product's microstructure is 100% ferrite with a ferrite grain size of 8.0–10.5. Furthermore, the pickling-direct hot-dip galvanizing process used in this invention omits the conventional cold rolling step, reducing process costs.
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