Stainless steel is a broad category of steel alloys that contain some proportion of chromium that prevents the metal from corroding and causing any type of damage caused by corrosion. It is worth noting that the variation of stainless steel you are using will have a different amount of chromium and other metallic elements than the one you are working with in terms of the alloy.

316 stainless steel, one of the most popular alloys for stainless steel, contains molybdenum in its composition. As opposed to 304 stainless steel, which is the most common form of stainless steel, this material is characterized by higher resistance to corrosion caused by chloride and other acids. Due to this, it is perfect for outdoor uses in harsh environments such as marine environments or applications in which potential exposure to chlorides might be present. 

There are different kinds of 316 steel, including 316L, which can be used in different applications. Due to the lack of carbon and molybdenum that is present in 316L stainless steel, it is different from typical 316 stainless steel as it contains less carbon and molybdenum. It is the purpose of this article to explain the fundamental differences between the various alloys so that you can choose the one that is right for your application.

It is important to note that there are several grades of stainless steel, which can be classified into four major categories. There are several types of stainless steel, but austenitic stainless steel is one of the most important. According to their chemical composition, austenitic stainless steel alloys can be further subdivided into a number of groups. A stainless steel grade that is often highlighted belongs to the 300 series, which is one of the most popular grades. I believe that these grades are highly versatile and their applications cover a wide range of areas, including the shipping industry, marine engineering, general engineering, the petrochemical industry, and the pharma, and food industry. Among the 300 series alloys, grade 316 is the second most commonly used alloy among all of them. Stainless steel grade 316 has a high degree of modifiability, just like most austenitic stainless steel alloys. There are a lot of modifications that are made to stainless steel based on the applications they are used for.

The modifications consist of minor additions or subtractions to the elements of the specific chemical composition. In general, modifications are made by adding or subtracting a few elements. For instance, marine grade 316 stainless steel has a higher content of carbon in its alloy. The carbide precipitate formed by carbon at elevated temperatures causes sensitization at the grain boundary precipitates when carbon forms a carbide precipitate. The metal becomes weak during welding operations because of the sensitization that takes place during the process. There is a tendency for welding temperatures to be higher than normal as they often need to melt some metal before they can fuse it with the other part or fuse together to form a complete piece when welding. Due to this, the melted part of the weld zone, which is the heat-affected zone of the weld, tends to have lesser corrosion resistance properties when compared with the rest of the surface of the component. It is important to keep in mind that since the other surface area has not been heated due to the welding treatment, the corrosion resistance remains stable. Stainless steel components with grades 316 or 316L can experience this problem when they are welded together. This problem was eventually addressed by manufacturers by devising a low-carbon version of this alloy as a solution to this problem.

The difference between 316 and 316l stainless steel

316 and 316L are basically the same steel except for the fact that 316L has a higher carbon content. 316L has a content of less than 0.03%, while 316 has a content of less than 0.08%. A characteristic of austenitic stainless steels is the presence of carbon, which is a very easy element to cause intergranular corrosion between grains. Generally, the lower the carbon content of the material, the lower the tendency for intergranular corrosion to occur. Consequently, 316L has a stronger corrosion resistance than 316, and the price of 316L is higher than that of 316, due to the increased corrosion resistance.

Despite the fact that the alloy has elements that have changed, it may still be possible to dual-certify the material, because the changes tend to be very minimal. Thus, the stainless steel alloy that has been dual-certified is going to be labeled as 316/316L. Due to this, it would be almost the same price for both of these alloys if they were compared with one another.

316 and 316l comparison

As well as the fact that the carbon content in stainless steel grade 316L is lower than that in stainless steel grade 304, manufacturers also add nitrogen to the alloy in order to make it stronger. There are several reasons why nitrogen should be added to the alloy for a variety of reasons. As a result of the reduction of carbon in stainless steel grade 316, there is a decline in the overall mechanical strength of the material. Secondly, its ability to withstand heat is also on the decline, due to a decline in its tolerance. In spite of this, it is due to the fact that there is less carbon in the chemical composition of grade 316L that it is possible to weld it without any susceptibility to intergranular corrosion as a consequence of the low carbon content.

Difference between 316 and 316l corrosion resistance

As we have already mentioned, the objective of introducing grade 316 stainless steel in the market is to take advantage of its excellent weldability. Reducing the carbon content in the alloy, effectively reduces its vulnerability to intergranular corrosion, in particular in the heat-affected weld zone, which is one of the most vulnerable areas. This low-carbon version of grade 316, which is similar to grade 316, is also referred to as ‘marine grade steel’ because of its resistance to seawater and brine solutions, similar to grade 316. Due to this, the alloy has also been dual-certified in order to meet the needs of a variety of applications. The material also has the ability to withstand atmospheric corrosion or what is also called oxidation resistance, which is similar to grade 316. There are also applications in which dual-certified alloys could be useful, such as for the production of halogen compounds, such as chlorine, fluorine, and bromine. As a result of their resistance to corrosion, these products form an integral part of the consumer goods industry due to their durability.

The difference in the strength of stainless steel tubes

In comparison to 316L stainless steel pipe, the tensile strength of 316 stainless steel pipe is higher than that of 316L stainless steel pipe. In comparison to 520MPa, the tensile strength of 316 stainless steel pipe is higher than that of 316L stainless steel pipe. There is only a tensile strength of 480Mpa greater than 316 stainless steel pipe when it comes to tensile strength. Stainless steel pipes can gain a significant amount of strength thanks to carbon, which is a strong austenite-forming element that contributes to their strength.

Differences in practical applications

As far as the cost difference between 316L stainless steel and 316 stainless steel is concerned, it is not a significant one. It is obvious that the corrosion resistance and weldability of stainless steel 316L are much better than the corrosion resistance and weldability of stainless steel 316. The stainless steel factory’s perspective is that they are reluctant to produce because the demand for ordinary 316 stainless steel is very low, which makes them hesitant to produce. Therefore, it is actually the low-carbon versions of stainless steel 316 L that circulate in the market at the moment. 316 stainless steel is rarely sold unless there is a specific demand for it, and this is the case most of the time.

 Differences in welding

There is a negative effect of carbon on the corrosion resistance of stainless steel pipes, which can be attributed to its presence. As a result of the inherent low-carbon composition of 316L stainless steel, it exhibits a lower corrosion resistance after welding than, for example, 316 stainless steel, which is more common in stainless steels that need to be welded. In addition, 316L stainless steel has good corrosion resistance, and after welding 316 stainless steel, the weld section must be solution annealed to ensure that it is corrosion-resistant. In the case of 316L stainless steel, solution annealing is not needed after the welding of 316L stainless steel is used.

Differences in corrosion resistance

316L stainless steel pipe is characterized by greater corrosion resistance than 304 stainless steel pipe and is suitable for strong corrosion areas such as the seaside. In addition, it is recommended not to consider the previous conditions when considering the 316 stainless steel pipe.

The difference in the scope of use

There are many situations in which stainless steel pipe 304 is sufficient to satisfy the requirements of the application in most cases. As a result of the high price of the 316L stainless steel pipe, from the perspective of material cost, the amount of 316L stainless steel pipe that should be used is approximately 1.5 times that of 304 stainless steel pipe, so the amount of 316L steel pipe should be customized accordingly