Quality characteristics and requirements of stainless steel

Because of the different uses of the products, the processing technology and the quality requirements of raw materials are different
(1) material:
DDQ (deep drawing quality) material which are used in deep drawing (wash) use of materials, which is everyone talking about soft materials, the main feature of this material is the extension rate is high (more than 53%), low hardness (less than 170%), the internal grain grade between 7.0~8.0, deep drawing good. At present, many enterprises producing thermos bottles and pans have higher processing ratio (BLANKING SIZE/ product diameter), and their processing ratio reaches 3, 1.96, 2.13 and 1.98 respectively. SUS304 DDQ timber is mainly used for these requirements higher processing ratio of products, of course, processing more than 2 of the products generally need to go through a few times stretch to complete. If the extension of raw materials can not reach, in the processing of deep drawing products, products are easy to produce cracks, pull through phenomenon, affecting the qualified rate of finished products, of course, also increases the cost of the manufacturers;
The general material: mainly used in DDQ in addition to the use of outside material, the material is relatively low elongation (more than 45%), and the higher hardness (less than 180), the internal levels of grain size between 8.0~9.0, compared with DDQ material, its deep drawing performance is worse, it is mainly used for products no stretch can be obtained, as a kind of tableware spoon, spoon, fork, electrical appliances, steel etc.. But compared with DDQ material, it has one advantage, that is, BQ is relatively good, mainly because of its slightly higher hardness.
(2) surface quality:
Stainless steel sheet is a very high price material, the customer's surface quality requirements are also very high. But the stainless sheet in the production process inevitably there will be various defects, such as scratches, pits, creases, pollution, and its surface quality, like scratch, creases etc. these defects whether senior or junior materials are not allowed, and the pitting defects in the spoon, spoon, fork, is never allowed because, when polishing is difficult to sell it. According to the degree and frequency of various defects on the surface, we can determine the grade of the quality of the surface so as to determine the grade of the product.
(3) thickness tolerance:
In general, stainless steel products, the requirements of material thickness tolerances are different, like two kinds of tableware and insulation Cup, thickness tolerances for general higher requirements for -3~5%, and a class of general requirements -5% tableware thickness tolerances, steel requirements -10%, the hotel with timber thickness tolerance requirements for -8% refrigerator, distributors of thickness tolerance the general requirements in -4%~6%. At the same time, the export of different products will also lead to customer requirements for raw material thickness tolerance. The demand for thickness tolerance of general export customers is high, while domestic enterprises require relatively low thickness tolerances (mostly for cost considerations), and some customers even require -15%.
(4) weldability:
The requirements of welding performance vary with the use of different products. A class of tableware generally does not require welding performance, and even including some pot enterprises. But the vast majority of products need raw material welding performance, like two kinds of tableware, thermos cup, steel pipe, water heater, water dispenser, etc..
(5) corrosion resistance:
The vast majority of stainless steel products for the good corrosion resistance, like one or two kinds of tableware, kitchenware, water heater, water dispenser, some foreign businessmen also do the corrosion resistance test of the product: NACL water solution is heated to boiling, pour the solution after a period of time, washing and drying, the weight loss is determined by the extent of corrosion (Note: product for polishing, abrasive cloth or paper containing the composition of Fe will lead to surface rust test)
(6) polishing performance (BQ property):
At present, stainless steel products are generally polished in production process, only a small number of products such as water heaters, water dispensers, such as the tank does not need polishing. Therefore, the polishing performance of the raw materials is very good. The main factors affecting the polishing performance are the following:
Surface defects of raw materials. Such as scratches, pits, pickling etc..
Material quality problem. Hardness is too low, polishing is not easy to shine (BQ is not good), and the hardness is too low, in the deep stretch of the surface orange peel phenomenon, thus affecting the BQ. BQ with high hardness is relatively good.
(3) after deep drawing, the surface area of the area with large deformation will also have small black spots and RIDGING, which will affect the BQ property.