As we all know, steel plate is easy to rust after being placed outside and oxidized by air for a long time, which not only affects the appearance, but also affects the price of steel plate. In particular, the requirements for laser plate surface are quite strict. As long as there are rust spots, production cannot be carried out. The uncertainty of operation risk will greatly increase. In case of cutter breakage, the raised rust spots will cause wear of laser head. So what should we do with rusty steel plates?
1. Original manual derusting
The so-called original derusting refers to manual derusting. This is a long and hard process. Although the heat can be used in this process with the help of blade, hammer and other tools, the rust removal effect of steel plate is not very ideal.
2. Derusting of power tools
Power tool derusting refers to the method of using compressed air or electric energy to drive the derusting tool to produce circular or reciprocating motion. When contacting with the surface of steel plate, use its friction and impact force to remove rust, oxide skin, etc. The derusting efficiency and quality of power tools are several streets away from pure manual work, which is also the common derusting method in general coating engineering.
In case of rain, snow, fog or wet weather, the surface of steel plate shall be coated with primer to prevent back rust. If the rust has returned before the primer is applied, the rust shall be removed again and the primer shall be applied in time.
3. Spray derusting
The purpose of rust removal by jetting is to achieve high-speed impact and increase friction force by using the effect of abrasives drawn in the impeller center of the jetting machine and jetting abrasives at the blade tip.
4. Spray derusting
The spray rust removal method is to use compressed air to spray the abrasive on the surface of the steel plate at high speed and remove the oxide scale, rust and dirt through the impact force and friction force of the abrasive, so that the surface roughness of the steel plate can be obtained, and the adhesion force of the paint film will be enhanced.
5. Chemical derusting
Chemical derusting is also called pickling derusting. Through the reaction of acid and metal oxide in acid wash solution, the metal oxide is dissolved to remove the oxide and rust on the steel plate surface.
There are two general pickling methods: common pickling and comprehensive pickling. Steel is easy to be oxidized by air after pickling, so passivation must be carried out to improve its antirust ability.
Passivation treatment refers to a means used to form a protective film on the surface of steel plate after pickling in order to prolong the time of rust return, so as to improve its rust resistance.
According to the specific construction conditions, different treatment methods can be adopted. After acid pickling, the steel plate shall be rinsed to neutral with hot water immediately and then passivated. In addition, the steel can also be cleaned with water immediately after pickling, and then neutralized by adding 5% sodium carbonate solution. The alkali solution can be cleaned with water, and finally passivated.
6. Flame derusting
Flame rust removal of steel plate refers to the removal of rust on the surface of steel plate after heating by wire brush after flame heating operation. Before derusting the steel plate surface, the thick rust layer attached to the steel plate surface shall be removed first, and then the rust shall be removed by flame heating.
