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Stainless steel and welding Information
Types of Stainless Steel
ive types of steel, each with numerous variations, fall under the stainless steel umbrella. All are categorized based on their microstructure—the result of both chemistry and the way in which the steel is heated and worked. Microstructure has a large influence on steel’s strength, ductility, and other physical and chemical attributes.
Three types of stainless are most commonly found in standard fabrication shops. Austenitic stainless steel is probably the most widely used, especially in typical machining and fabrication applications. Hard martensitic stainless steel is frequently used in high-wear applications such as hardfacing. Ferritic stainless steel is less expensive than other forms of stainless, making it a favorite for such consumer products as automotive exhaust components.
A fourth type, duplex stainless steel, is a combination of austenite and ferrite microstructures, making it stronger than either of its components but also more difficult to work with. Finally, precipitation-hardening stainless steels include other alloying elements—niobium, for example—that increase both strength and cost. Both duplex and precipitation-hardening stainless are specialty types used primarily in high-performance applications, such as aerospace and process industries, and we will not go into detail about them.
prepare stainless steel weld so that the weld come out good and clean
The key to any good weld is clean metal, but what is the best way to clean metal before you start welding? Depending on the tools you have and the overall goal of the project there are a few ways to prep your metal to get a nice clean weld every time.
The best welds come from pure clean metal to metal contact, any foreign materials in the welding area can cause welding imperfections. Even brand new metal must be prepped before it can be welded because there is usually a coating put on new metal so it does not rust or oxidize during the shipping process. This is a factor that is often overlooked and will always result in a weak and ugly weld. Be mindful, once you remove this coating the metal is exposed to the elements, if left out unprotected steel will begin to rust, even indoors.
To start, the type of welding you are doing will determine how you prep the metal. Inherently MIG welding steel does not need the metal to be perfectly clean. On the other extreme, TIG welding aluminum requires contaminant free metal to create a strong clean weld. In all of the examples below you can see the difference the dull color of the “new metal” (left) compared to how it looks after it is properly prepped (right).
Why is it hard to make a stainless steel weld
Once thought of as a major challenge the welding of stainless steels and most other corrosion resistant alloys is more often described as ‘different’ in stead of ‘more difficult’ amongst welders today. The welding of stainless steels and the properties of the welds with regard to corrosion resistance and mechanical properties do involve a mixture of metallurgical, geometrical and surface finishing aspects.
Nickel (plus carbon, manganese and nitrogen) promotes the formation of austenite and chromium (plus silicon, molybdenum and niobium) encourages the formation of ferrite, so the structure of welds in stainless steels can be largely predicted on the basis of their chemical composition. Because of their different microstructures, the alloy groups have both different welding characteristics and susceptibility to defects.
What is the best way to weld stainless steel?
Welding is a way to combine pieces of stainless steel together for repair work and even craft projects. To begin a weld, set the steel in place over a welding table using clamps and jigs. Then, join the steel together through MIG or TIG welding. MIG welding is an inexpensive way to weld larger pieces together, while TIG welding is perfect for more delicate, stronger welds. No matter which type of torch you choose for your project, you can make the project a success with the right equipment and technique.
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