Difference between 304 stainless steel pipe and 316 stainless steel pipe

What is stainless steel pipe?

Stainless steel pipe is a hollow steel pipe that is not easy to rust. It is non-magnetic and is usually used as a pipeline for conveying fluids. As an important building material, stainless steel pipes are widely used in the construction and industrial fields. Its corrosion resistance, strength and processing performance make it an ideal choice.

Classification of stainless steel pipes:
According to the production process, stainless steel pipes can be divided into two basic categories: Stainless steel seamless pipes and Stainless steel welded pipes.  According to the outer diameter shape of the steel pipe, it can be divided into round pipes and special-shaped pipes. Round steel pipes are widely used. Seamless stainless steel pipes, also known as stainless steel seamless pipes, are made of steel ingots or solid tubes through perforation into rough pipes, and then hot rolled, cold rolled or cold drawn.

When buying stainless steel pipes, the words stainless steel are often followed by 304 or 316 numbers. These two numbers refer to the model of stainless steel. However, it is difficult for people to tell the difference between stainless steel 304 and  stainless steel 316. Today we will distinguish the two in detail from the perspectives of chemical composition, density, performance, price, and application areas. After reading this, I believe you will have a clear understanding of these two types of stainless steel.

1. Chemical composition

304 stainless steel pipe and 316 stainless steel are both austenitic stainless steel. The difference between the two in chemical composition is: 316 stainless steel increases nickel (Ni) by reducing the chromium (Cr) content, and increases molybdenum (Mo) by 2%-3%. This structural organization greatly improves the corrosion resistance and wear resistance of stainless steel, so the performance of 316 stainless steel is better than 304 stainless steel.

304 stainless steel: C≤0.08, Si≤0.75, Mn≤2.0, P≤0.04, S≤0.03, Ni: 8.0~11.0, Cr: 18.0~20.0
316 stainless steel: C≤0.08, Si≤0.75, Mn≤2.0, P≤0.04, S≤0.03, Ni: 10.0~14.0, Cr: 16.0~18.0, Mo: 2.0~3.0

2. Density

The density of 304 stainless steel is 7.93g/cm³, and the density of 316 stainless steel is 7.98g/cm³. The density of 316 stainless steel is higher than that of 304 stainless steel.

3. Performance characteristics
In addition to having better wear resistance and corrosion resistance than 304 stainless steel, 316 stainless steel also has better heat resistance, because the carbide formed by the molybdenum (Mo) element in 316 stainless steel is extremely stable, which can prevent the grain growth when austenite is heated and reduce the overheating sensitivity of steel.

304 stainless steel is acid-resistant, alkali-resistant, high density, polished without bubbles, high toughness, and good processing performance; 316 stainless steel not only has the performance characteristics of 304 stainless steel, but also resists corrosion from special media, can improve corrosion resistance to chemical hydrochloric acid and the ocean, and improve corrosion resistance to salt water halogen solutions.

4. Price
316 stainless steel has added molybdenum and nickel, while 304 stainless steel does not, so the price of 316 stainless steel will be slightly higher than that of 304.

What are the common stainless steel materials?

1. 201 stainless steel is one of the 300 series stainless steels, with relatively high acid resistance, alkali resistance, and density.
2. 202 stainless steel is a low-nickel, high-manganese stainless steel material, commonly used in shopping malls or municipal projects.
3. 301 stainless steel is a metastable austenitic stainless steel with relatively good rust resistance and a relatively complete austenitic structure.
4. 303 stainless steel is a stainless, acid-resistant steel that is easy to cut and can be used for the production of automatic beds, bolts, and nuts.
5. 304 stainless steel has relatively good processing performance and relatively high comprehensive performance. It is a general type of stainless steel.
6. 304L stainless steel is called low-carbon stainless steel. It has relatively superior comprehensive performance.
7. 316 stainless steel is austenitic stainless steel, which contains Mo element inside. It has good high temperature resistance and corrosion resistance, and can be used in pipelines and dyeing equipment.

The difference between the application of 304 and 316 stainless steel:

The application range of 304 stainless steel is very wide. The pots, pans, cups, tableware, and food equipment commonly used in households all use 304 stainless steel, while 316 stainless steel is often used in food, machinery, petroleum and other fields, and is more common in the manufacturing industry.

Article source: https://article-realm.com/article/Business/67888-Difference-between-304-stainless-steel-pipe-and-316-stainless-steel-pipe.html