Due to different uses, each product has different processing techniques and raw material quality requirements. Generally speaking, different stainless steel products require different raw material thickness tolerances. For example, Class II tableware and thermos cups generally require a higher thickness tolerance of -3~5%, while Class I tableware generally requires a thickness tolerance of - 5%, steel pipes require -10%, hotel freezer materials require a thickness tolerance of -8%, dealers' thickness tolerance requirements are generally between -4% and 6%. At the same time, the difference in domestic and foreign sales of products will also lead to different customer requirements for raw material thickness tolerances. Generally, export product customers have higher thickness tolerance requirements, while domestic sales companies have relatively low thickness tolerance requirements (mostly due to cost considerations), and some customers even require -15%.
①DDQ (deep drawing quality) material: refers to the material used for deep drawing (punching), which is what everyone calls soft material. The main characteristics of this material are high elongation (≧53%) and relatively high hardness. Low (≦170%), the internal grain grade is between 7.0~8.0, and the deep drawing performance is excellent. Many companies that produce thermos bottles and pots generally have relatively high processing ratios (BLANKING SIZE/product diameter), reaching 3.0, 1.96, 2.13, and 1.98 respectively. SUS304DDQ material is mainly used for products that require a higher processing ratio. Of course, products with a processing ratio exceeding 2.0 generally require several passes of stretching to be completed. If the raw material elongation is not met, the product will easily produce cracks and pull-throughs when processing deep-drawn products, which will affect the qualification rate of the finished product and of course increase the manufacturer's cost;
② General materials: Mainly used for materials other than DDQ purposes. This material is characterized by relatively low elongation (≧45%), relatively high hardness (≦180HB), and an internal grain size grade of 8.0~9.0 Compared with DDQ material, its deep drawing performance is relatively poor. It is mainly used for products that can be obtained without stretching, such as spoons, spoons, forks for tableware, electrical appliances, steel pipes, etc. But it has one advantage compared with DDQ material, that is, its BQ properties are relatively better, which is mainly due to its slightly higher hardness.
Stainless steel sheet is an inexpensive material, but customers have very high requirements for its surface quality. Stainless steel sheets will inevitably have various defects during the production process, such as scratches, pitting, sand holes, dark lines, creases, contamination, etc. Therefore, their surface quality, such as scratches, creases, etc., are high-grade materials. Defects such as pitting and sand holes are not allowed when making spoons, spoons, and forks, because they are difficult to throw away during polishing. The surface quality level needs to be determined based on the degree and frequency of various surface defects to determine the product grade.
