Production Process

The tin plate consists of five parts, from the inside to the outside, they are the steel substrate, the tin-iron alloy layer, the tin layer, the oxide film and the oil film.

The production process of tin plate mainly includes electroplating tin, reflow, cathode passivation and oiling. The electroplating tin plating process deposits a layer of metallic tin on the cold-rolled plate. The reflow process forms a thin tin-iron alloy layer between the cold-rolled substrate and the pure tin layer. The cathodic passivation treatment and oiling process form passivation respectively. chemical film and oil film.

Classification

1. Equal-thickness tinplate: a cold-rolled electroplated tinplate with the same amount of tin plating on both sides.

2. Differential thickness tin plate: Cold-rolled electroplated tin plate with different amounts of tin plating on both sides.

3. First-grade tin-plated plate: The electroplated tin-plated plate that has been inspected online is suitable for conventional painting and printing on the surface of the entire steel plate under normal storage conditions. It must not have the following defects: ① Pinholes penetrating the thickness of the steel plate; ② The thickness exceeds the deviation specified in the standard; ③ Surface defects such as scars, pits, wrinkles, rust, etc. that have an impact on the use; ④ Shape defects that have an impact on the use.

4. Second-level tin-plated sheet: The surface quality is lower than that of first-level tin-plated sheet. Small-area and obvious surface defects or shape defects such as inclusions, wrinkles, scratches, oil stains, indentations, burrs, and burnt spots are allowed. No Ensure that the entire steel plate can be conventionally painted and printed.

Process

Tin plate is generally manufactured according to the following processes:

1. Hot rolling: In a continuous hot-rolling mill, the slab is hot-rolled at a higher rolling temperature to produce sheared hot-rolled steel plates and continuous coils;

2. Pickling: The pickling operation line is used to remove the oxide scale on the surface of the strip before cold rolling. This type of large reduction cold rolling is needed to produce the thin tin plate required by the market. Good pickling effect will also help improve the surface quality and cleanliness of the steel plate to meet the needs of the subsequent electroplating tin plating process;

3. Cold rolling: The pickled coils are cold rolled on a cold rolling mill to reach the specified thickness. To ensure product quality during the cold rolling process, it is important to ensure uniform thickness of the cold rolled strip, obtain good surface quality, and meet flatness requirements. These quality characteristics will be reflected in the final product quality of tin plate;

4. Annealing: Cold rolling will elongate the grain structure of the strip along the cold rolling direction, making the strip hard and brittle. However, during the annealing process, the cold-rolled strip is reheated and kept at a certain temperature in a reducing atmosphere for a period of time to form new non-deformed grains so that the material properties meet the specified use requirements. There are two annealing methods: bell annealing (batch annealing) and continuous;

5. Flat rolling or secondary rolling: Flat rolling or secondary rolling is usually the final processing. This rolling process can produce a slight cold work hardening phenomenon in the strip, while also increasing some toughness and eliminating the yield plateau phenomenon. Moreover, cold rolling and or secondary rolling can also make the strip meet the specified surface finish requirements and improve the plate quality and flatness.