Stainless steel grades are classified into four major categories, and one of the most important categories is austenitic stainless steel, which is further put into several groups based on its chemical composition. The 300 series is one of the most highlighted steel grades, which is very versatile, and its utility covers several areas. Under this series, grade 316 is the most widely used alloy. When checking the cost of 316 stainless steel tube, you may come across the term 316l stainless steel tubes. To choose the right one for your application, you need to know the differences between the two types.
The main difference between 316 and 316l stainless steel is their carbon content. 316 stainless steel has a significantly high amount of carbon compared to 316L material. However, both materials are used interchangeably in various industrial applications. Both materials have 18% chromium, 8% nickel, and 4% molybdenum content, which allows them to show excellent resistance against seawater and chloride-rich environments.
Though there are elemental changes between the two grades, their cost difference is very mild as the composition is similar with slight modifications. The material could be dual-certified because the changes tend to be at a very minimal level. Hence the cost of a 316 stainless steel tube will be almost the same as that of a 316L pipe.
Differences In Properties
In the 316L grade of steel, the carbon content is limited to a maximum of 0.03% of the total composition. Both materials can handle certain levels of corrosion and strength and are also highly capable of high-temperature applications. Since 316L has a lower carbon content, it is widely used for welding applications as it does not allow grain structure formation during welding as part of the chloride precipitation. This property is highly valued in heavy welding applications as the welding needs to last longer and be strong even at the developing joints. The low carbon content also allows 316L stainless steel to have high toughness to the products, thus helping in abrasion resistance of the materials made of 316L grade stainless steel.
Comparing 316 and 316L allows the customer to select the right product types. While both materials are used in the production of nuts, bolts, pipe fittings, flanges, pipes and other products, 316L is preferred for building applications. However, there is not much difference between 316 and 316L corrosion resistance since both materials have the same amounts of chromium, molybdenum, nickel, manganese, silicon and sulfur. But the lower carbon content in 316L allows it to have slightly higher corrosion resistance.
The mechanical properties of 316 and 316L vary slightly due to their composition. 316 material has a yield strength of 30 ksi, while 316L has 25 ksi. Also, the tensile strength of both the materials has a difference of 5ksi, but the elongation rate and max hardness remain the same. Although both materials can be used at elevated temperatures, 316 is used more in such situations because only certain specific applications require the 316L variant. Since 316L material has a little toughness added to its mechanical properties due to less carbide precipitation during welding, it is highly preferred for medical implants over 316 stainless steel.
Both 316 and 316L stainless steel alloys are marine-grade steels, but some key differences must be noted. The first is that 316L has a lower proportion of carbon in its composition, which decreases the risk of carbon precipitation. In contrast, the 316 steel grade has a mid-range level of carbon and 2-3% molybdenum, which increases resistance to corrosion, high temperatures, and acidic elements. However, both materials have great malleability, making them suitable for bending, stretching, spinning and deep drawing.
How To Choose Between The Two?
- Corrosion Resistance
This is an important factor to consider when choosing between 316 and 316L grades of steel. Due to its low carbon content, 316L would be the superior choice for high corrosion and high-temperature applications. Thus, its welds will not decay as they have better intergranular corrosion resistance.
- Magnetic Properties
When purchasing 316 or 316L products, keep in mind that the former has very low responsiveness to magnetic fields. However, it can undergo processes like cold forming and welding, where the austenitic crystal structure is transformed into ferromagnetic martensite. On the other hand, 316L steel is more susceptible to gaining some degree of magnetism.
- Practical Applications
Though both grades of stainless steel can be used in a wide variety of industries, 316 is primarily used in construction and infrastructure because it is strong, resistant to pitting, and corrosion-resistant in most cases. 316L is more popular for pharmaceutical and photographic equipment as it can withstand welding and corrosive chemicals.
If you want to make the right choice, contact a supplier that can help you by providing an inventory of stainless steel products. Learn more about the difference and choose as per your requirements.