The process of steel structure can't do without the cooling step. The reason for cooling is not only to improve the quality of steel, but also to increase its toughness and extend its service life, so that it will be more smooth when welding. So, what should we pay attention to when we cool down? Let's get to know:
1. High temperature graded quenching shall be carried out in a neutral salt bath of 580-620 ℃.
2. For large and complex steel structure processing, in order to reduce deformation and cracking, pre cooling treatment can be carried out during quenching, but the time shall be controlled. Generally, it shall be controlled within a few seconds to dozens of seconds according to the shape of the processing, provided that the secondary carbide can not be precipitated to reduce the hardness and red hardness of the tool, and corrosion pitting is not allowed.
3. The undercooled austenite in processing is very stable and has high hardenability. Even if it is air-cooled, it can be subject to martensitic structure, but air cooling will cause the oxidation of the tool surface, and it is possible to precipitate eutectoid carbide, so air cooling is not used as much as possible.
The above is about the steel structure processing should pay attention to when cooling, its use in building materials is very extensive, its cooling is a kind of protection to it, improving its toughness can also increase its benefits. Therefore, before construction, we must do a good job in its cooling work, so as to facilitate its smooth construction.