Welded stainless steel pipe
applications can include anything from medical equipment to offshore drilling towers. Selecting the right alloy is one of the ways in which you can meet the specific requirements of your application and also guarantee job success. Depending on the elements of the alloy, you can improve the properties of your tube; from improving its ductility, to increasing its resistance to corrosion. Here is a summary of some of the most common alloy elements, including the ways in which their chemicals affect the properties of a tube:
Nickel improves the ductility of the alloy
Nickel is the backbone of the Incoloy, Inconel and Monel alloy families and is an additive in austenitic stainless steels. By creating a face-centered cubic crystal structure (FCC), nickel increases the ductility of the alloys and constitutes an important component in metals subjected to plastic deformation. In general, austenitic steels will exhibit impressive ductility properties with only 8% nickel. High nickel alloys, such as N200 and 52Ni, produce some of the most ductile tubes available.
Chromium and molybdenum increase corrosion resistance
Known for its corrosion resistance, chromium forms a thin layer of rust on the surface of the steel that acts as an outer shell that protects the metal inside. Most austenitic stainless steels require about 18% chromium to guarantee a basic level of resistance; However, some alloys have more.
Molybdenum is especially resistant to chloride attacks and is effective for preventing pitting corrosion in marine applications. You can add molybdenum to nickel alloys to increase its strength and resistance to deformation at high temperatures. Stainless steels, including 316, 317 and 904L, as well as Inconel 825 and 6Mo alloys, are well known for including molybdenum to increase corrosion resistance.
Carbon increases strength
When added to an alloy, carbon atoms are deposited at the intercalated sites of the crystal grids and alter the way the structure deforms under pressure. However, although adding carbon to alloys usually makes them more resistant, they can also become more fragile. Low carbon alloys are useful in applications where the pipe will work at high temperatures. Generally, austenitic stainless steels contain 0.02-0.08% carbon by weight. Steels such as 316, 317 and 304 contain low carbon variants in order to increase the functionality of the alloy and decrease susceptibility to corrosion through sensitization.