Customers often inquire about 316 stainless steel bellows, but they get confused when we recommend 316L stainless steel bellows. We have identified two main reasons for this confusion. First, misinformation. The end customers actually want 316L stainless steel bellows, but during the communication process, there may be a typographical error where the letter “L” is omitted, or 316L stainless steel is mistakenly equated with 316 stainless steel. Second, differences in the application market. In the United States, 316 stainless steel is also a common material for metal bellows. Therefore, we have prepared the following article to help you better understand the differences between these two types of stainless steel.
The 316 series is a popular austenitic stainless steel and a commonly used material for metal bellows. It is highly favored for its superior corrosion resistance compared to 304 and 321 stainless steel. The primary types within this series are 316 stainless steel and 316L stainless steel, along with several variants such as 316H and 316Ti. The chemical composition of 316 stainless steel and 316L stainless steel is almost identical, with the key difference being the carbon content. 316L stainless steel has a lower carbon content than 316 stainless steel. The “L” in 316L stands for “low carbon.” The carbon content in 316L stainless steel does not exceed 0.03%, whereas it is 0.08% in 316 stainless steel. This difference in carbon content affects the weldability and corrosion resistance.
Weldability
316L stainless steel does not require annealing after welding, eliminating concerns about stress issues in bellows material caused by high-temperature welding. This helps reduce processing procedures and lowers production costs for bellows manufacturers. For some custom bellows, the cost of annealing after welding might not be significant. However, for mass-produced standard bellows, this is crucial to the manufacturer’s profit margin. In China, the vast majority of bellows manufacturers prefer to use 316L stainless steel, which is also the default option when not otherwise specified.
Corrosion resistance
The 316 series stainless steel has better corrosion resistance than 304 stainless steel and is commonly used in various applications in marine environments. Due to its lower carbon content, 316L stainless steel has better intergranular corrosion resistance to 316 stainless steel.
Cost
Although the carbon content of 316 and 316L stainless steel is different, there is basically no difference in the cost that customers are concerned about.
