First, Iron Now on the market with iron production of more screws, it is very cheap, processing is relatively rough. But we all know that iron has one of the biggest flaws. That is, in the air is easier to rust, once the rust iron screws of the connection performance will be greatly reduced. Therefore, in the instrumentation industry, if the use of iron screws, in addition to its processing accuracy requirements are relatively high, but also need to deal with its comparison. Common treatment methods are mainly blackened and galvanized. Either way, the treatment is designed to block contact between the screws and the air, which prevents it from rust. Of course, after these surface treatment, the price of screws also need to increase a lot, the general situation of the same kind of screws, iron blackening of the finished screw price and 304 of the price is similar. Therefore, in some cases, the price of Dongguan screws can not be judged only by the material.
Second, carbon steel Carbon steel is also very common to use, in the material market, carbon steel is not just a type, it has low carbon steel, medium carbon steel, high carbon steel and alloy steel Four, this classification is mainly based on the carbon content of carbon steel to score. In the case of carbon steel screws, high steel screws are rare, and medium carbon steel is used most frequently.
Third, stainless steel screws. Stainless steel materials are also divided into a variety of, one is austenitic, this material is relatively high heat resistance, but also corrosion resistance, the other is martensite, martensite material corrosion resistance is much worse than austenite, but it also has many advantages, such as its wear resistance is very good.
IV, Brass Brass is also used to process Dongguan screws, because the price of brass is significantly higher than carbon steel and stainless steel, so the general price of copper screws are relatively high.