Stainless steel is great for many different metal applications, particularly if you need great corrosion resistance. It’s great for many projects, but because there are so many different types, it varies in how weldable it is between types – some are excellent, while others are not easy to weld and may not even be weldable at all depending on who you ask.
At Wasatch Steel, we can help you identify the best grades of stainless steel if you require welding processes. Let’s get started on what will be a two-part blog.
In many areas, ferritic stainless steels are considered the best overall grade to weld. Some grades of ferritic steel do still have chromium or other alloying elements, but these amounts are significantly lower than austenitic steel (which we’ll go over below) – this means they’re more weldable. Corrosion is not a concern, meaning you don’t have to worry quite as much about maintaining corrosion resistance.
In addition, risks of hot cracking during the welding process are very low. Ferritic stainless steels can sometimes be subject to excessive grain growth if they’re exposed to excessive heat, causing a loss in toughness in ductility. However, grades like 407 and 430 are excellent and tend to avoid this.
Austenitic stainless steels come with a variety of potential welding processes, and a variety of grades that are good for these. Grades like 304, 308, 316, 321 and 347 are generally best for welding.
Note, though, that intergranular corrosion is a risk with these grades. They have high amounts of carbon, which combines with chromium to create a protective chromium oxide layer. Chromium carbides will then open up the area around the weld to corrosion over time. Luckily, you can fight this – allows like 304, 308 and 316 come in low-carbon formats as well, designated by an L at the end of the grade. In addition, grades 321 or 347 are stabilized, meaning extra titanium or niobium are used to combine with carbon before it has a chance to combine with chromium.