How to Weld 321 Stainless With E309

Grade 321 stainless steel should be heated slightly before welding.

E309 welding wire is used to weld both stainless steel and carbon or low-alloy steels. As an all-around material, E309 has good fill properties and produces a clean weld with strong penetration. Grade 321 stainless steel contains much more titanium than other steels in an effort to offset chromium carbide precipitation, a situation that occurs during the welding process of some steels that can lead to part failure. As 321 stainless steel is most commonly used on aircraft parts, such as jet engines and exhaust manifolds, strength of the part and the weld are critical, and can be obtained with E309 welding wire.

Things You'll Need

• Welding clamps
• MIG welder
• Welding helmet
• Propane torch

Instructions

1. Clamp the 321 stainless steel parts together in the manner in which they are to be welded using the welding clamps. Place them on a solid work surface, such as a work bench or a concrete floor.

2. Open the side cover of the MIG welder and insert the spool of E309 wire in place of the existing welding wire. Turn on the welder and feed the E309 wire through the welding gun so that the wire extends approximately 1/4 of an inch from the tip of the welding gun.

3. Set the feed speed for the welder to its middle range with the feed speed dial, and then set the amperage at 1/4 full power. Attach the negative ground clamp from the MIG welder to the 321 stainless steel.

4. Heat the joint where the 321 stainless steel will be fused with the propane torch. It only has to reach 150 degrees, so you don't have to get the metal red-hot. This is done to pull any liquid impurities out of the weld area so that they cannot interfere with proper weld adhesion.

5. Position the tip of the welding gun approximately 1/4 of an inch from the joint to be welded, and then lower your welding helmet. Pull the trigger on the welding gun to begin to form the weld puddle. When it has reached a diameter of approximately 1/4 of an inch, begin pushing the weld puddle across the joint being welded.

6. Push the weld puddle across the joint being welded, moving the welding tip in small circles as you do. By pushing the puddle rather than pulling it, you will find that you will achieve better weld penetration, and as a consequence, a stronger part. When the weld is complete, release the trigger for the welder and allow the part to cool naturally. Quenching the part could result in micro fissures to form in the steel compromising the strength of the part.

7. Clean the excess slag off of the weld with a wire brush to complete the welding operation.

Tips & Warnings

• Always wear safety equipment, such as a welding helmet, when you are welding. The spark created by the welding process is extremely bright and can permanently damage your eyesight.

References

• "Welding Complete: Techniques, Project Plans & Instructions"; Editors of CPi; 2009
• "Welder's Handbook, Revised: A Guide to Plasma Cutting, Oxyacetylene, ARC, MIG and TIG Welding"; Richard Finch; 2007
• "Welding Fundamentals"; Roger Jellison; 1995