304 Stainless Steel sheet is widely used in many fields due to its excellent corrosion resistance. However, its corrosion resistance is affected by many factors.
1. Alloy element content
Chromium and nickel are the key alloying elements of 304 Stainless Steel sheet. The chromium content needs to reach about 18% to form a stable and dense passivation film on the steel surface to prevent oxygen and water from reacting with the steel. When the chromium content is insufficient, the passivation film is difficult to form completely and the corrosion resistance will be reduced. Nickel can enhance the corrosion resistance of stainless steel, make the alloy's crystal structure more stable, and improve its resistance to media such as acids and alkalis. The nickel content is generally around 8%.
2. Surface state
The surface quality of 304 Stainless Steel sheet has a significant impact on corrosion resistance. Plates with high surface finish are difficult for media to adhere to and the probability of corrosion is lower. If there are scratches or pits on the surface, these defects will destroy the integrity of the passivation film, form corrosion sources, and accelerate the corrosion process. The surface treatment method is also critical. The corrosion resistance of polished and passivated plates is better than that of untreated plates.
3. Usage Environment
Medium type: In different chemical media, the corrosion resistance of 304 Stainless Steel sheet varies significantly. It has good corrosion resistance in the atmosphere and water, but its corrosion resistance will drop significantly in strong oxidizing acids (such as nitric acid) and strong reducing acids (such as hydrochloric acid). In an environment containing chloride ions, chloride ions will destroy the passivation film and cause pitting and crevice corrosion.
Temperature and humidity: As the temperature rises, the rate of corrosion reaction accelerates. In a high temperature and high humidity environment, 304 Stainless Steel sheet is more susceptible to corrosion.
4. Processing technology
Cold working will change the internal structure of 304 Stainless Steel sheet and generate residual stress. These stress concentrated areas are easy to become the starting point of corrosion, reducing corrosion resistance. During the welding process, if the welding process is improper, the organization and composition of the weld will change, forming a chromium-poor area and reducing the corrosion resistance of the weld.
In order to give full play to the corrosion resistance of 304 Stainless Steel sheet, the above factors must be strictly controlled during production, processing and use. Through reasonable alloy design, surface treatment and correct use methods, the corrosion resistance of 304 Stainless Steel sheet can be improved and its service life can be extended.
If you are eager to learn more about hot rolled stainless steel plates, please do not hesitate to contact Jiangsu Tisco Metal for more consultation. We have an excellent professional team.
