1.Can water-based rust inhibitors be used on cold-rolled coils?
It is feasible, but with strict conditions. Water-based rust inhibitors (also known as rust preventatives or water-based rust inhibitors) can be used for short-term inter-process rust prevention of cold-rolled coils or temporary protection in specific enclosed environments. However, compared to oil-based rust inhibitors, their rust prevention period is shorter (usually a few days to a few weeks), and they have higher requirements for application processes, water quality, and drying conditions. They are not recommended for long-term storage or sealing of finished products for export by sea.
2.What are the advantages and disadvantages of water-based rust inhibitors compared to displacement-type rust inhibitors?
Short rust prevention period (several days to several weeks)
Low unit cost
Non-flammable and poses no fire hazard
Easy to clean, some products are biodegradable
Most can be directly subjected to electrophoresis, coating, etc. (good compatibility)
3.What are the main risks of using water-based rust inhibitors on cold-rolled coils?
The core risk lies in the paradox of "using water to prevent rust"-if the water-based rust inhibitor is not completely dry or is applied unevenly, residual moisture is trapped between the sheet surface and the rust-inhibiting film, which can lead to localized electrochemical corrosion, causing the rust to spread faster than if no treatment were applied. Furthermore, cold-rolled coils have extremely small interlayer gaps when stacked in coils; if the water-based rust inhibitor is not completely dry, the moisture is difficult to evaporate, easily causing large areas of rust spots on the sheet surface.
4.In what scenarios is it appropriate to use water-based rust inhibitors on cold-rolled coils?
Rust prevention between short-cycle processes-For example, cold-rolled coils need to be stored for several days to two weeks after leveling, shearing, and stamping, before subsequent cleaning, phosphating, or coating.
Sheet protection after uncoiling-After steel sheets are cut into individual sheets, spraying or immersion with water-based rust inhibitors can prevent short-term corrosion caused by hand sweat and environmental moisture.
Temporary indoor storage-Used in well-ventilated, humidity-controlled indoor warehouses for the protection of semi-finished products with clearly defined turnover cycles.
5.What are the key points to keep in mind when using water-based rust inhibitors?
Water Quality Requirements – Deionized or purified water must be used for preparation; chloride ions in tap water will severely weaken the rust-preventive effect.
Complete Drying – Forced hot air drying is required after coating (board temperature typically needs to be ≥60℃) to ensure complete evaporation of moisture before winding or stacking.
Uniform Coating – Use roller coating or spraying methods to ensure continuous film formation and avoid missed areas.
Process Validation – It is recommended to conduct stacking simulation tests before mass production to simulate the interlayer humidity environment under winding conditions and confirm that there is no risk of rust before widespread application.