Soft tin-plate and its making process

Abstract

The soft tin-plate consists of C not more than 0.006 wt%, Mn 0.10-0.20 wt%, Al 0.025-0.075 wt%, Si not more than 0.03 wt%, Ti 0.03-0.08 wt%, P not more than 0.015 wt%, S not more than 0.015 wt%, N not more than 0.003 wt%, and O not more than 0.004 wt%, except Fe and inevitable impurities. Its production process includes the following steps: smelting steel, continuous casting and rolling, hot rolling, acid pickling and rolling, continuous annealing, flattening and tin plating.

Description

technical field [0001] The present invention relates to soft tinplate and its manufacturing method, in particular to soft tinplate with HR30T of 49±3 (hereinafter referred to as T-1CA) and soft tinplate with HR30T of 53±3 (hereinafter referred to as T-1CA) -2CA) and its manufacturing method. The soft tin plate is produced by continuous annealing of titanium-IF steel, and is mainly used for the production of flower basket barrels with enlarged diameters, can lids with complicated deformation and stamped and deformed cans. Background technique [0002] According to the Japanese Industrial Standard JIS G 3303, the range of hardness (HR30T) of tinplate with different quenching and tempering grades is shown in Table 1. Among them, T-1 to T-3 are soft tinplates, and T-4 to T-6 are hard tinplates. [0003] level HR30T hardness range T-1 46～52 T-2 50～56 T-2.5 52～58 T-3 54～60 T-4 58～64 T...

AI Technical Summary

Problems solved by technology

Since niobium-IF steel is sensitive to production process parameters, especially to hot rolling process parameters, the performance of the product is unstable, and its recrystallization temperature is high, and the required annealing temperature is high. When organizing the production of this product, it is necessary to use More transition material and longer transition time, especially in the continuous annealing furnace, it is easy to produce buckling or even broken belt, so the performance of the plate is poor, and the heat energy consumption is large, and the alloy element niobium is expensive, so its production relatively high cost

In addition, niobium-IF steel has poor plasticity, although the anisotropy is not large, its overall mechanical properties are worse than titanium-IF steel

Finally, niobium is radioactive to a certain extent when it is mined and smelted, and it is still controversial whether the tinplate with niobium added (mainly used in the food industry) is harmful to the human body

[0008] At the same time, although the patent discloses that hot rolling coiling is carried out between 600°C and 800°C, the coiling temperature is too high, especially the upper limit temperature is obviously too high, and practical operation cannot be carried out. The coiling temperature protected by this patent The temperature range is obviously unreasonable, because when coiling close to 800°C, the steel plate is seriously oxidized, and even if it is above 630°C, the oxide scale will obviously thicken, which will not only affect the pickling speed of the subsequent process, but also affect the surface of the final product quality

In addition, although the patent discloses the use of annealing between 670°C and 800°C, since the patent uses niobium IF steel to produce soft tinplate, the annealing temperature is close to 670°C within the annealing temperature range specified in the patent (for example, 670°C to 740°C), it is difficult for the steel plate to complete recrystallization at the normal unit speed, that is, it is impossible to produce qualified soft tinplate. Therefore, the annealing temperature range protected by this patent is obviously unreasonable