Research on the process principle and microscopic mechanism of stainless steel surface treatment sandblasting
1. Overview of sandblasting process principle
Stainless steel surface treatment sandblasting is a process that uses a high-speed jet of sand to impact the surface of stainless steel. Sandblasting equipment uses compressed air or other power sources to give sand particles enough kinetic energy to hit the stainless steel surface at a certain speed and angle. In this process, the sand particles are like tiny "projectiles" that continuously hit the stainless steel material. For example, when compressed air accelerates the sand particles to a speed of tens or even hundreds of meters per second, the sand particles collide violently with the stainless steel surface. This collision force can remove the oxide layer, pollutants, rust and some surface defects on the stainless steel surface, giving the stainless steel surface a new microscopic morphology.
2. Material removal of microscopic mechanism
At the microscopic level, the material removal of sand particles on the stainless steel surface is mainly based on two mechanisms. One is the micro-cutting effect. When the sharp sand particles hit the stainless steel at a high speed, the front end of the sand particles cuts into the stainless steel surface like a knife, and the surface material is shaved off bit by bit. This effect is more obvious when the sand particles are hard and the angle is appropriate. The second is impact deformation and fracture. The impact of sand particles causes local plastic deformation on the surface of stainless steel. When the deformation accumulates to a certain extent, the stress inside the material exceeds its strength limit, which will cause tiny cracks to be generated and expanded, and eventually the material will be detached from the surface in the form of fragments or particles. For example, for some stainless steels with relatively low hardness, under the impact of sand particles with greater impact force, the impact deformation and fracture mechanism may play a leading role, causing the surface material to be quickly removed.
3. Surface morphology shaping of microscopic action mechanism
As the sandblasting process continues, the microscopic morphology of the stainless steel surface is gradually changed. The impact of sand particles forms countless tiny pits on the surface. The size, depth and distribution of these pits depend on factors such as the particle size, speed, injection angle and sandblasting time of the sand particles. Smaller sand particles will form denser pits, while larger sand particles will produce larger and deeper pits. At the same time, due to the randomness of sand particle impact, the distribution of pits also shows a certain disorder. This unique microscopic pit structure increases the roughness of the stainless steel surface, increases the specific surface area of the surface, provides a better adhesion basis for subsequent coating, electroplating and other processes, and also changes the optical properties and feel of the stainless steel surface to a certain extent.
4. Changes in surface properties of microscopic action mechanisms
The performance of the stainless steel surface has also changed after sandblasting treatment. From the perspective of mechanical properties, the surface hardness will be improved due to the impact strengthening effect of sand particles, and the wear resistance of the surface will be improved to a certain extent. For example, on some stainless steel parts that need to withstand friction and wear, the surface treated with sandblasting can better resist wear. From the perspective of chemical properties, due to the removal of oxide layers and pollutants and the increase in surface roughness, the corrosion resistance of stainless steel may change in some cases. In some cases where the corrosive environment is weak, appropriate sandblasting treatment can form a uniform passivation film on the stainless steel surface and improve its corrosion resistance; but in a strong corrosive environment, an overly rough surface may reduce corrosion resistance due to the easy accumulation of corrosive media, and further protective treatment is required.
