Choosing Base Enamel for Cold- vs. Hot-Rolled Steel

The base material properties of cold-rolled steel sheets and hot-rolled steel sheets differ significantly, and the selection logic for enamel base coats for the two is completely different.

Cold-rolled steel sheets undergo cold rolling and annealing finishing, resulting in a smooth and clean surface with minimal oxide scale and low impurity content. The substrate exhibits good stability, produces very few defects during enameling, and has relaxed requirements for base glaze compatibility, allowing for a wide range of selection. The core considerations for base glaze selection are substrate adhesion, surface smoothness, and compatibility with the firing process.

During production, enamel glazes are usually selected based on the firing temperature and product type. It is necessary to ensure that the glaze layer adheres firmly and the porcelain surface is delicate and uniform, making it suitable for various civilian enamel products such as home appliances and kitchen and bathroom products. The process has a high tolerance for error.

Hot-rolled steel sheets are formed at high temperatures, resulting in substrates with micropores, residual impurities, and numerous hydrogen trap structures. During high-temperature enameling, hydrogen easily accumulates and precipitates within the substrate, readily causing defects such as scaling, bubbling, and porcelain cracking. Therefore, the primary principle for selecting a base glaze is explosion-proof and anti-scaling. General-purpose base glazes cannot be used on this type of steel sheet; a specialized, breathable, explosion-proof base glaze must be selected. This base glaze relies on its porous structure to dissipate hydrogen, preventing porcelain cracking defects at their source. Simultaneously, the glaze and firing schedule must be matched to the steel sheet thickness and pretreatment quality, prioritizing production stability. The appearance of the porcelain surface is a secondary optimization goal, making it suitable for industrial enameled equipment, pipes, and other similar products.

In short, cold-rolled steel sheet base glaze is important for quality compatibility and has a wide range of selections; hot-rolled steel sheet base glaze is important for explosion-proof and defect-resistant and has specific selections. The two cannot be used interchangeably and must be strictly matched with the base material process plan.