1, stainless steel in the presence of chloride ion environment, corrosion quickly, even more than ordinary low carbon steel.
Chloride ion exists widely, such as salt/sweat/seawater/sea breeze/soil and so on. In the presence of chloride ion, stainless steel corrodes quickly, even exceeding ordinary low carbon steel. Therefore, there is a requirement for the use environment of stainless steel, which needs to be wiped frequently to remove dust and keep it clean and dry.
There is an example in the United States: an enterprise uses oak containers to hold solutions containing chloride ions. The container has been used for nearly a hundred years, and it was planned to be replaced in the 1990s. Because the oak material is not modern enough, the container leaked due to corrosion 16 days after it was replaced with stainless steel.
2. The solution treatment is not in place
The alloy elements are not dissolved in the matrix, which leads to low alloy content and poor corrosion resistance in the matrix.
3, intergranular corrosion
This material without titanium and niobium has a tendency of intergranular corrosion. Adding titanium and niobium and stabilizing treatment can reduce intergranular corrosion. A high alloy steel resistant to air or chemical corrosive medium. Stainless steel is a kind of steel with beautiful surface and good corrosion resistance. It does not need surface treatment, such as color electroplating, but exerts its inherent surface properties. It is widely used and is usually called stainless steel.
High alloy steels such as 13 Cr steel and 18-8 Cr-Ni steel are its representative properties. From the metallographic point of view, because stainless steel contains chromium, a very thin chromium film is formed on the surface, which isolates the oxygen invading the steel and plays a role in corrosion resistance. In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 12% chromium. Used where welding is needed.
The low carbon content minimizes carbide precipitation in the heat affected zone near the weld, which may lead to intergranular corrosion (welding corrosion) of stainless steel in some environments.
4. Surface mark refers to the linear or point dent defect on the surface of 304 stainless steel after deep processing or grinding of processed products.
Cause: There are foreign bodies on the surface and die surface, and there are scars on the surface of blank holder.
Countermeasures: remove foreign bodies and scars before processing, or remove orange peel by full grinding.
5. Orange peel phenomenon refers to the phenomenon of orange peel on the surface of 304 stainless steel molded products under grinding or other conditions.
Reason: insufficient grinding, the bigger the processing, the more serious the orange peel, the coarse particle size of raw materials and the softening of heat treatment.
Countermeasures: Fully grind the deep-processed products, select suitable heat treatment conditions and control the particle size of raw materials.
Extended data:
SUS304 generally refers to 304 stainless steel.
304 stainless steel is a common material in stainless steel, with a density of 7.93 g/cm? , also known as 18/8 stainless steel in the industry. High temperature resistance of 800℃, good processability and high toughness, widely used in industry, furniture decoration industry and food and medical industry.
Common marking methods in the market are 06Cr 19Ni 10 and SUS304, in which 06Cr 19Ni 10 generally represents national standard production, 304 generally represents ASTM standard production and SUS 304 represents Japanese standard production.
304 is a general-purpose stainless steel, which is widely used to manufacture equipment and parts that require good comprehensive performance (corrosion resistance and formability). In order to maintain the inherent corrosion resistance of stainless steel, steel must contain more than 18% chromium and more than 8% nickel. 304 stainless steel is a stainless steel brand produced according to American ASTM standard.
Baidu Baike -304 Stainless Steel