Grade 304L, the low carbon version of 304, prevents carbide precipitation which could act as an inroad to corrosion. Of these, Grade 304 is the most versatile and most widely used, with excellent forming and welding characteristics. The most common type of stainless steels are the chromium-nickel austenitic alloys (300 series), including 304 and 316 stainless. Even different alloys within groups require different welding procedures. Each of these types has a different internal microstructure, which affects their welding properties. The five basic types of stainless include austenitic, ferritic, duplex, martensitic, and precision hardening. Each of these affect the weldability of the alloy. Welding Different Types of Stainless Steelĭifferent types of stainless steel contain different alloying materials in different proportions. Keep in mind that any wire brushes or other tools that have been used on regular carbon steel should never be used on stainless, because particles of carbon will react with the chromium. When preparing a stainless steel workpiece for welding, use a stainless steel wool or a stainless wire brush to remove any oxides on the surface. In addition to these measures, using the correct settings on the welding machine and moving the welding torch along at a good pace will help prevent overheating and warping. If the workpiece is a small-diameter tube or an enclosed piece with no outside access, an argon gas purge can be used to cool it down. The aluminum has a much faster heat absorption rate, so will tend to draw heat quickly away from the stainless. One way to prevent overheating is lining the work pieces by clamping an aluminum or copper “chill bar” along both lengths. It also helps to choose a low-carbon stainless grade, such as 304L. For this reason, it’s important to keep the temperature of the workpiece within the recommended range. During the welding process, this can cause warping – affecting both the shape and strength of the final piece. Stainless steel has a low thermal conductivity, which means that a lot of heat can build up quickly in one spot. This can leave areas more susceptible to rust, and no longer “stainless.” But instead of reforming, chromium in the stainless will combine with carbon. These oxidized chromium molecules form a thin, tight film, called a passivation layer that acts as a barrier against the surrounding air, preventing any further oxidation of the steel.ĭuring the welding process, the passivation layer is breached. The chromium on the surface of a piece of stainless oxidizes (rusts) quickly in the presence of oxygen or water molecules in the atmosphere. Stainless steel includes a minimum of 10% chromium, a highly reactive metal. With an understanding of the specific application and the alloy to be welded, stainless steel actually can be one of the best metals for welding. Yet stainless has a reputation for being tricky to weld. Stainless steel is widely used in many industries and applications, due to its corrosion resistance, strength, and ability to be sanitized.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |