Stainless Steel Welding: Choosing the Best Types of Steel

What makes a stainless steel good for welding? The secret is in the alloy ratios.

All quality welding requires a high level of material weldability. Weldability is affected by the chemical composition of the metal. For example, steels with higher levels of carbon aren't as weldable due to their low ductility.

So, which types of stainless steel should you use when your application involves welding? Let's take a look.

Types of Stainless Steel for Welding

When choosing the right stainless steel for your project, you need to consider if it will be welded. Different types of stainless steel respond differently to welding. Some are better than others for this type of fabrication.

Here are the main types of stainless steel and their properties.

Austenitic

Austenitic stainless steels are the best option for welding. They contain a low ratio of carbon, which means they're more ductile. Higher ductility equals greater weldability.

They also have the highest levels of chromium, which makes them the shiniest and most durable. Austenitic steels are the most common stainless steels across all industries, and are the best for highly corrosive environments. This category includes the common and sturdy grades 304(L), 316(L), and 347. Here's a full list:

Martensitic

Martensitic steels are the second best option, though their composition may require pre- and post-weld treatment. Chemically, they fall between austenitic and ferritic steels in terms of carbon and chromium levels. Martensitics include the popular and shiny 400 series.

-403
-410
-416
-420/F
-440/A/C/F

Ferritic

Ferritic steels aren't as suitable for welding. They have higher levels of carbon, which causes low ductility, high grain growth, and sensitization. Ferritic steels aren't as shiny due to the higher amounts of carbon and lower ratio of chromium.

-405
-430/F
-439
-442
-446

Duplex

Duplex stainless steels are great for welding, and have been growing in popularity over recent years. Duplexes are a combination of ferritic and austenitic steels. They're closer chemically to austenitics, though with a higher yield strength and greater stress resistance.

Choose Your Stainless Steel Wisely!

That's the skinny on how to choose your material for stainless steel welding. If your application involves a lot of welding, choose a stainless steel with a high chromium to carbon ratio. The austenitic series are your best bet.