Production technology and quality control of galvanized sheet

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First, modern production line process analysis

1. Pre-treatment of key processes

Alkali wash degreasing: The NaOH solution of pH12.5 is used to remove 5-8g/m² of rolling oil

Reduction annealing: Heating to 720-850 ° C in H₂+N₂ atmosphere to eliminate work hardening

Zinc liquid composition: Modern production line adopts Zn-0.2% al-0.03mg formula, which improves fluidity by 15%

2. Coating control technology

The air knife system accurately controls the zinc layer thickness through 0.3-0.5MPa air pressure, and the error is controlled within ±3g/m². Wisco CGL production line adopts double air knife design to achieve single-sided differential thickness coating (such as 20/10g/m²).

2. Prevention and control of common quality defects

1. Surface defect map

%E6%A0%B9%E6%8D%AE%5B6%5D(@ref)%E6%8F%8F%E8%BF%B0%E7%BB%98%E5%88%B6

Zinc scar: Zinc slag particle size > 0.5mm need to replace the zinc pan

White rust: When the storage humidity is > 70%, the ZnO oxide layer is produced within 72 hours

2. Mechanical properties control

Automobile plate requires yield strength ≥140MPa, elongation ≥34%. Edge wave defects are eliminated by in-line tension straightening (elongation 0.5-1.5%). The 1200MPa galvanized sheet developed by Hangang has been commercialized.

Zhishang Steel has always been a pioneer in custom steel and special supplies, and has been recognized for its efforts in enhancing work efficiency and product quality. In addition to ISO9001:2015 certification, we also adhere to strict quality policies and proprietary procedures. If you have any questions, please contact us to provide the best type of product solution for your pre-painted, coil coating metal process, we will closely support after-sales service to ensure that your subsequent problems can be solved in a timely manner, if you have any questions, please send email to info@zhishangsteel.com, we look forward to serving you.