November 16, 2023
1. Different carbon content
What the SS and L marks represent is that there is a difference in the carbon content of steel. SS has a high carbon content, and L represents ultra-low carbon. Taking 316L and 316SS as examples, the carbon content of 316SS is less than or equal to 0.08, and the carbon content of 316L is less than or equal to 0.03.
The carbon content of 316 is less than or equal to 0.08, the tensile strength is greater than or equal to 515MPa, and the yield strength is greater than or equal to 205MPa; while the carbon content of 316L is less than or equal to 0.03, the tensile strength is greater than or equal to 485MPa, and the yield strength is greater than or equal to 170MPa.
2. Different physical properties
316SS stainless steel is stronger than 316L, but 316L stainless steel has lower carbon content, so it is more resistant to corrosion. 316L is widely used in the chemical industry because of its excellent corrosion resistance. 316L is also a derivative of 18-8 austenitic stainless steel, with 2 to 3% Mo added.
On the basis of 316L, many steel types are derived. For example, 316Ti is derived by adding a small amount of Ti, 316N is derived by adding a small amount of N, and 317L is derived by increasing the Ni and Mo content.
The Mo content of 316L makes this steel type have excellent resistance to pitting corrosion and can be safely used in environments containing halogen ions such as Cl-. Since 316L is mainly used for its chemical properties, steel mills have slightly lower surface inspection requirements for 316L (compared to 304). Customers with higher surface requirements should strengthen surface inspection.
3. Different prices
Removing carbon from stainless steel requires a huge amount of energy, so even though the carbon content has dropped from 0.08% of 316 to 0.03% of 316L, the price is much higher.