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Chemical Compositions & Mechanical Properties of SS 304 Pipes
Jul 23, 2021
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The full name of SS 304 pipes is SUS304 stainless steel pipes. SUS304 stainless steel pipes belong to the stainless steel pipes of American grade materials. The stainless steel pipes of domestic grade materials are equivalent to 0Cr19Ni9 stainless steel pipes, which are usually replaced by 0Cr18Ni9. The rust prevention mechanism of stainless steel is the formation of alloy elements of dense oxide film, which can isolate oxygen contact and prevent continuous oxidation. Therefore, stainless steel is not actually "stainless".
There may be the following reasons for the rust phenomenon of 304 materials.
1. Chloride ion exists in the operational environment.
Chloride ion can be found in a wide range of substances, such as salt, sweat, seawater, sea breeze and soil. The stainless steel in the presence of chloride ions in the environment can be corroded quickly. The speed of the corrosion is even more than that of ordinary low-carbon steel.
Therefore, there are requirements for the operational environment of stainless steel pipes. The stainless steel pipes often need to be wiped to remove dust and keep them clean and dry. There is an example in the United States: an enterprise uses an oak container to hold a solution containing chlorine ions. The container has been used for more than 100 years. In the 1990s, it was planned to be replaced. As the oak material was not modern enough, the container leaked due to corrosion 16 days after the stainless steel replacement.
2. No solid solution treatment.
Alloying elements do not dissolve into the matrix, resulting in low alloy content in the matrix and poor corrosion resistance.
3. This titanium and niobium - free material have a natural tendency to intergranular corrosion. The addition of titanium and niobium can reduce the intergranular corrosion with stabilization treatment.
In the air or chemical corrosion medium, stainless steel can resist a kind of high alloy steel. The stainless steel has a beautiful surface and good corrosion resistance. It does not have to go through the plating color and other surface treatment. It plays the inherent surface performance of stainless steel which is used in a variety of steels. We usually call it stainless steel. The representative ones are 13 chromium steel, 18-8 chromium nickel steel and other high alloy steels.
From the perspective of metallography analysis, as the stainless steel contains chromium and the surface of the formation of a very thin chromium film, the film separates from the invasion of oxygen in the steel playing a role in corrosion resistance.
In order to maintain the inherent corrosion resistance of stainless steel, the steel must contain more than 12% chromium. 304 is a kind of universal stainless steel, which is widely used in the production of equipment and parts requiring good comprehensive properties (corrosion resistance and durability). Stainless steel 304 is a grade of stainless steel produced according to the American ASTM standard. 304 is equivalent to China's 0Cr19Ni9 (0Cr18Ni9) stainless steel. 304 contains 19% chromium and 9% nickel. 304 is the most widely used stainless steel and heat resistant steel. It can be used for food production equipment, ordinary chemical equipment, nuclear energy, etc.
The chemical composition of stainless steel 304:
C≤0.08
Si ≤1.00
Mn ≤2.00
P ≤0.045
S≤0.03
Cr18.00-20.00
Ni8.00~10.00
The SS 304 is 1Cr18Ni9.
There may be the following reasons for the rust phenomenon of 304 materials.
1. Chloride ion exists in the operational environment.
Chloride ion can be found in a wide range of substances, such as salt, sweat, seawater, sea breeze and soil. The stainless steel in the presence of chloride ions in the environment can be corroded quickly. The speed of the corrosion is even more than that of ordinary low-carbon steel.
Therefore, there are requirements for the operational environment of stainless steel pipes. The stainless steel pipes often need to be wiped to remove dust and keep them clean and dry. There is an example in the United States: an enterprise uses an oak container to hold a solution containing chlorine ions. The container has been used for more than 100 years. In the 1990s, it was planned to be replaced. As the oak material was not modern enough, the container leaked due to corrosion 16 days after the stainless steel replacement.
2. No solid solution treatment.
Alloying elements do not dissolve into the matrix, resulting in low alloy content in the matrix and poor corrosion resistance.
3. This titanium and niobium - free material have a natural tendency to intergranular corrosion. The addition of titanium and niobium can reduce the intergranular corrosion with stabilization treatment.
In the air or chemical corrosion medium, stainless steel can resist a kind of high alloy steel. The stainless steel has a beautiful surface and good corrosion resistance. It does not have to go through the plating color and other surface treatment. It plays the inherent surface performance of stainless steel which is used in a variety of steels. We usually call it stainless steel. The representative ones are 13 chromium steel, 18-8 chromium nickel steel and other high alloy steels.
From the perspective of metallography analysis, as the stainless steel contains chromium and the surface of the formation of a very thin chromium film, the film separates from the invasion of oxygen in the steel playing a role in corrosion resistance.
In order to maintain the inherent corrosion resistance of stainless steel, the steel must contain more than 12% chromium. 304 is a kind of universal stainless steel, which is widely used in the production of equipment and parts requiring good comprehensive properties (corrosion resistance and durability). Stainless steel 304 is a grade of stainless steel produced according to the American ASTM standard. 304 is equivalent to China's 0Cr19Ni9 (0Cr18Ni9) stainless steel. 304 contains 19% chromium and 9% nickel. 304 is the most widely used stainless steel and heat resistant steel. It can be used for food production equipment, ordinary chemical equipment, nuclear energy, etc.
The chemical composition of stainless steel 304:
C≤0.08
Si ≤1.00
Mn ≤2.00
P ≤0.045
S≤0.03
Cr18.00-20.00
Ni8.00~10.00
The SS 304 is 1Cr18Ni9.
