303 Stainless is typically not recommended for welding.

But there are times when we need to weld it

303 stainless steel is a free-machining austenitic stainless steel, specifically designed to offer excellent machinability.

It’s essentially a modified version of 304, with sulfur added to improve chip formation during machining. That’s great for turning, milling, or drilling—but not so much for welding.

Situations Where TIG Welding 303 May Be Considered

Low-Stress, Non-Critical Applications

You might weld 303 in situations where:

• The weld isn’t load-bearing
• Building up worn metal to restore dimensions.

In all cases, welding should be done with full knowledge of the risks.

Filler Metal Selection for Welding 303 Stainless

ER308L Filler Metal

The most commonly used filler for 303 is ER308L—the low-carbon version designed to match 304 stainless. It works adequately, though it won’t completely eliminate cracking risks.

Both ER309L and ER312 are Alternatives and ER312 has very high crack resistance

ER309L and ER312 have a higher alloy content, making them  more crack-resistant and suitable when welding dissimilar metals or questionable base materials like 303.