The difference between 304 and 316 stainless steel
Before understanding the difference between 304 and 316 stainless steel, let’s first understand the meaning of stainless steel.
“Stainless steel”, as its name implies: “Steel that will not rust”, then does stainless steel really not rust? Now let us learn about “stainless steel” through systematic learning.
Stainless steel (Stainless Steel) is the abbreviation of stainless and acid-resistant steel. It is called stainless steel that is resistant to weak corrosive media such as air, steam, and water, or is stainless steel; Corrosion steel is called acid-resistant steel.
Both 304 stainless steel and 316 stainless steel are often used in daily life as building materials. Different models of products must have different performances. What is the difference between 304 stainless steel and 316 stainless steel?
Simply put, 304 stainless steel and 316 stainless steel are austenitic stainless steels, stainless steel is often divided into martensitic steel, ferritic steel, austenitic steel, austenite-ferritic (duplex ) Stainless steel and precipitation hardening stainless steel, etc. In addition, it can be divided into chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel according to the composition. Among them, austenitic stainless steel has the best comprehensive performance and has no magnetism, so it is the most widely used in our daily life. Both 304 and 316 belong to austenitic stainless steel. 316 stainless steel is added with molybdenum on the basis of 304 stainless steel, which greatly improves the waterproof performance of 316 stainless steel.
In fact, different types of stainless steel only have different alloying elements added to them, so they have certain characteristics that we need, and 316 stainless steel is the same. When some properties of 304 stainless steel cannot meet our needs, 316 was developed.
1. Grade issue.
304 and 316 extend 304L and 316L respectively, and the respective grades are as follows:
304 is 0Cr18Ni9, 304L is 022Cr19Ni10;
316 is 0Cr17Ni12Mo2, 316L is 00Cr17Ni14Mo2.
| type | Serial number | SUS | Grade | chemical composition % | ||||||||||
| C | Si | Mn | P | S | Ni | Cr | Mo | Cu | N | Other | ||||
| 1 | 304 | 0Cr18Ni9 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.030 | 8.00-10.00 | 17.00-19.00 | – | – | – | – | |
| 2 | 304L | 022Cr19Ni10 | ≤0.030 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.030 | 8.00-10.00 | 18.00-20.00 | – | – | – | – | |
| 3 | 316 | 0Cr17Ni12Mo2 | ≤0.08 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.030 | 10.00-12.00 | 16.00-18.50 | 2.00-3.00 | – | – | – | |
| 4 | 316L | 00Cr17Ni14Mo2 | ≤0.030 | ≤1.00 | ≤2.00 | ≤0.035 | ≤0.030 | 10.00-12.00 | 16.00-18.00 | 2.00-3.00 | – | – | – | |
2. The problem of alloying elements.
It can be clearly seen from the table that the main difference between the chemical composition of 304 and 316 lies in Ni Cr Mo, and both Ni and Cr can increase the strength of steel. Mo can refine the grain of steel, improve hardenability and heat Strong performance, maintain sufficient strength and creep resistance at high temperatures.
3. Food grade issues.
Often people will ask if 304 is food grade? In fact, according to the material, the content of 304 material has reached food grade. There are about three common food grade materials in the market: 304, 316 and 430 stainless steel. 304 is commonly used in our small household appliances or water cups, 316 is some used in medical equipment, and 430 is often used as a stainless steel material for knives. However, we must clarify a concept here. It does not mean that the material is food-grade. It also includes whether the manufacturing process meets the food-grade standard. Just like Xiyouwo makes stainless steel pipes for decoration, it will In addition, the stainless steel pipe factory specializes in the production of food-grade stainless steel water pipes, and the required process steps are different.
4. Corrosion resistance issues.
316 stainless steel is the stainless steel produced by adding some molybdenum to the pitting corrosion resistance of 304 stainless steel. In various types of water (distilled water, drinking water, river water, boiler water, etc.), the corrosion resistance of 304 stainless steel and 316 stainless steel is almost the same, but when the content of chloride ions in the medium is very high, 316 stainless steel is more suitable.
5. Price issues.
Due to the molybdenum and nickel elements added to 316, 316 stainless steel is more expensive than 304 stainless steel.
The above is the difference between 304 and 316 stainless steel. All stainless steel materials have their specific functions and scope of use. Reasonable use of their advantages and disadvantages can create greater value for us.