Stainless steel is an alloy made up of iron and chromium, with other elements such as nickel, molybdenum, and manganese added in varying amounts. The chromium gives the steel its resistance to staining and corrosion. The higher the chromium content, the better the corrosion resistance. The addition of other elements gives the steel unique properties such as increased strength, improved resistance to heat, and improved magnetism.
The main advantage of stainless steel is its corrosion resistance. It does not corrode easily and does not rust like other metals. It is also stain resistant and easy to clean. This is why it is so widely used in many applications, especially those that involve exposure to moisture, chemicals, and other corrosive substances.
Another advantage of stainless steel is its durability. It is strong and can withstand a variety of conditions. It is also resistant to wear and tear, making it ideal for items that are used frequently, such as kitchen appliances and automotive parts.
Stainless steel is also non-magnetic, which makes it a great choice for medical instruments, such as scalpels and other surgical tools. It can also be used in applications where magnetism needs to be avoided, such as in computers and electronics.
Finally, stainless steel is an attractive material. It can be polished or brushed for a sleek, modern look. It is also available in a variety of colors and finishes, making it easy to match with other materials and colors in a design.
Stainless steel is an incredibly versatile material that can be used in a variety of applications. From kitchen appliances to medical instruments and automotive parts, stainless steel is an excellent choice for its superior resistance to corrosion, staining, and wear and tear. With its attractive look and range of colors and finishes, stainless steel can be used to create beautiful designs and products.
The Different Grades of Stainless Steel
In many industries, two of the most common types of stainless steel are 304 and 316. With 304 being the standard “18/8” stainless, it is considered the most durable and easy to form into various shapes such as stainless steel sheet, plate, bar, and tube. 316 steel’s resistance to chemicals and marine environments make it a popular choice among manufacturers.
The five classes of stainless steel are organized based on their crystalline structure. 304 and 316 stainless steel are within the austenitic grade class which makes them non-magnetic and prevents them from being hardenable by heat treatment.
304 Stainless Steel Properties
The chemical composition of Grade 304 is composed of the following elements: Carbon (0.08%), Manganese (2.00%), Silicon (0.75%), Phosphorus (0.045%), Sulfur (0.03%), Chromium (18.0%-20.0%), Nickel (8.0%-10.6%), and Nitrogen (0.1%). Its physical properties include a melting point of 1450°C, density of 8.00 g/cm^3, a thermal expansion of 17.2 x10^-6/K, and a modulus of elasticity of 193 GPa. Its mechanical properties include a tensile strength of 500-700 Mpa, elongation of A50 mm at 45 min %, and hardness of 215 Max HB.
Common applications of 304 SS include the medical industry due to its ability to withstand strong cleaning chemicals without corroding, and the food industry due to its ability to meet the FDA’s sanitary regulations. Other applications include fryers, food prep tables, kitchen equipment, cookware, silverware, siding, elevators, bathroom stalls, trays, and surgical tools.
316 Stainless Steel Properties
The chemical composition of Grade 316 is composed of the following elements: Carbon (0.08%), Manganese (2.00%), Silicon (0.75%), Phosphorus (0.045%), Sulfur (0.03%), Chromium (16.0%), Nickel (10.0%), and Molybdenum (2.0%). Its physical properties include a melting point of 1400°C, density of 8.00 g/cm^3, a thermal expansion of 15.9 x 10^-6, and a modulus of elasticity of 193 GPa. Its mechanical properties include a tensile strength of 400-620 Mpa, elongation of A50 mm at 45% min, and a hardness of 149 max HB.
Common applications of 316 SS include water-handling equipment such as boilers and water heaters, marine parts such as boat rails, wire rope, and boat ladders, medical equipment, and chemical processing equipment. The addition of Molybdenum makes it more resistant to corrosion than 304, making it ideal for marine environments and hospitals.
When comparing the heat resistance of 304 and 316, the melting range of 304 is about 50 to 100 degrees Fahrenheit higher than 316. However, they both have good resistance to oxidization in intermittent service up to 870°C (1500℉) and in continuous service at 925°C (1697℉). 304 handles high heat well, but continuous use at 425-860 °C (797-1580 °F) may cause corrosion. 316 performs best in temperatures above 843 ℃ (1550 ℉) and below 454 ℃ (850°F).
The addition of Molybdenum and the increase of nickel content makes 316 more expensive than 304. On average, the price of 316 stainless steel is 40% higher than the price of 304 SS.
Which is Better?
When deciding which one to use for different applications, it is important to consider the pros and cons of each. For instance, 316 stainless steel is more resistant than 304 to salt and other corrosives, making it ideal for marine environments and hospitals. However, if a product does not need strong corrosion resistance, 304 is a practical and economical choice. For many applications, 304 and 316 are interchangeable.