Welding of SS 321 and SS 304

Stainless steel is a popular choice for various industrial applications due to its corrosion resistance and durability.

When two different grades of austenitic stainless steel, such as SS 321 and SS 304, need to be welded together, it is important to understand the specific challenges and selection of the right filler wire.

Welding SS 321 and SS 304 requires careful consideration of factors such as their metallurgical differences, potential for intergranular corrosion, and the heat input required for successful fusion.

In this blog, we will explore the welding process for SS 321 and SS 304 and discuss the best practices to weld SS304 to SS321 grade.

Filler wire for welding SS304 to SS321

When welding SS304 to SS321, there are several filler wire options available that conform to the AWS A5.9 specification.

You can use ER321, ER347, and ER308 classification filler wires for welding SS304 to SS321. The characteristics of these wires are:

ER321: This filler wire is specifically designed for welding SS321 to itself or to other stainless steels such as SS304. It contains titanium, which stabilizes the carbon and prevents intergranular corrosion. ER321 is recommended for welding applications where high-temperature strength and corrosion resistance are required.

ER347: This filler wire is also suitable for welding SS321 to SS304, as well as other stainless steels. It contains columbium (also called Niobium-Nb), which stabilizes the carbon and prevents intergranular corrosion. ER347 is recommended for welding applications where high-temperature strength and corrosion resistance are required, as well as for applications where the welded joint may be exposed to high-stress conditions.

ER308L: This filler wire is similar to ER308 but contains a lower carbon content to prevent intergranular corrosion. It is also suitable for welding SS304 to SS321 or other stainless steels. ER308L is recommended for welding applications where high-temperature strength and corrosion resistance are required, and where intergranular corrosion must be avoided.