There are various grades of stainless steel, which can be divided into four main categories. One of the most important categories is austenitic stainless steel. Austenitic stainless steel alloys are further divided into several categories based on their chemical composition. One of the most popular grades of stainless steel is the 300 series. These grades are highly versatile and their uses cover a wide range of fields, including shipping, marine engineering, general engineering, the petrochemical industry, and the pharmaceutical and food industries. That said, grade 316 is the second most used alloy in the 300 series. As with most austenitic stainless steel alloys, Grade 316 can be modified. Modifications to stainless steels are often based on their application.
Typically, modifications are small additions or subtractions of elements for a specific chemical composition. For example, marine grade 316 stainless steel has a high carbon content in the alloy. Carbon forms carbide precipitates at high temperatures and causes sensitization at grain boundary precipitates. As a result of sensitization, the metal weakens during welding operations. Welding temperatures are usually high because they require molten metal in order to fuse it to another part or to fuse itself to form a complete part. As a result, the melted portion (i.e., the heat-affected weld area) tends to have weaker corrosion resistance compared to the rest of the component's surface. Since the other surface areas are not heated by the welding process, the corrosion resistance remains stable. This is a problem affecting welded parts made of Grade 316 stainless steel. To address this issue, manufacturers have designed lower carbon versions of this particular alloy.
316 and 316l Stainless Steel Price Differences
Although there are elemental variations in the alloy, the material can be double certified because the variations tend to be at very small levels. As a result, double certified alloys will be labeled 316/316L. as a result, both alloys are priced nearly the same.
316 and 316l Comparison
In addition to the lower carbon content in 316L stainless steel, manufacturers also add nitrogen to their alloys. There are several reasons for adding nitrogen to the alloy. First, as the carbon content decreases, the overall mechanical strength of 316 stainless steel decreases. Second, its heat resistance also decreases. However, it is the lower carbon content in its chemical composition that makes it possible to weld 316L stainless steel without being affected by intergranular corrosion.
Differences in corrosion resistance between 316 and 316L
As mentioned earlier, the 316 grade of stainless steel was introduced to the market with the goal of achieving excellent weldability. Reducing the carbon content effectively reduces the alloy's vulnerability to intergranular corrosion, especially in heat-affected weld zones. Similar to Grade 316, the low carbon version of the alloy can also be referred to as marine grade steel, as it is resistant to seawater and brine solutions. As such, the alloy is also dual certified to meet the needs of a wide range of applications. In addition, like Grade 316, it is resistant to atmospheric corrosion or also known as oxidation resistance. Dual certified alloys are also useful in applications containing halogenated compounds, including chlorine, fluorine and bromine. Because of their corrosion resistance, they are an integral part of the consumer goods industry.
