Strength grades of stainless steel combination screws and screws
Have you ever learned about the strength grade of combination screws? Different combination screws have different strength levels. There are many national standards for combination screws, and there will be a distinction between strength levels. Combination screws are no exception. The strength grade of the combined screw is distinguished according to the raw material of the screw wire and the hardness target of the screw wire. The general combination screw materials are divided into stainless steel and iron, and stainless steel is divided into stainless steel 201, stainless steel 304 and stainless steel 316. Iron is divided into three types: low carbon steel, medium carbon steel, and high carbon steel.
Carbon steel combination screws refer to iron combination screws. Generally, iron combination screws are classified into grades 4.8, 8.8, 10.9 and 12.9. However, the combination screws of grade 10.9 and grade 12.9 are rarely used in the market, so we will not talk about them here. And the combination screws on the market are more commonly used combination screws of grade 4.8 and 8.8.
4.8 grade combination screws are generally made of 1010A screw wire rods. After the screw wire rods are beaten into screws, they are combined with spring flat washers. After production, this 4.8 grade combination screw does not need to be hardened. Its hardness can reach 4.8.
8.8 grade combination screws are generally made of screw wire 10B21 piers. After the screw and wire piers are made into screws, they are equipped with spring washers and flat washers. They can pass through the automatic elastic flat washer machine to rub the three pieces together. Fasten the spring-flat washer combination on the screw, and the spring-flat washer will not fall off. After the combination screw is produced, it needs to be hardened to make the hardness reach 8.8. After the hardness reaches 8.8, we need to take it for electroplating. In order to avoid hydrogen embrittlement of the spring washer in the 8.8-level combination screw with added hardness, it is easy to break. In this way, we have to perform hydrogen removal treatment on the hardened combined screws, which can be electroplated just after the hydrogen removal.
In a word, there are many kinds of standard grade strengths of combination screws, but generally only two types are used in the market, one is the 4.8-level combination screw strength, and the other is the 8.8-level combination screw strength. 4.8-level combination screws are the most used in the market and customer needs, and the scale of application is extensive. As for the standard strength of 8.8-level combination screws, we generally refer to 8.8-level hexagon socket head combination screws, 8.8-level pan head combination screws, and 8.8-level external hexagon combination screws. These three are more commonly used.
