by Jason Becker
Depending on the type of work you do, there may come a time when you have to weld dissimilar metals together. In this episode we discuss welding 304 Stainless Steel to A36 Mild Steel using SMAW.
This process is very common in structural applications where a steel connection needs to be joined to stainless steel. I used this application quite frequently when I worked at Disney. We had to make steel to stainless connections in many of the attractions that used water as an effect. Due to the heavy chlorine in the water to prevent the spread of bacteria, stainless steel was used in place of steel wherever it would interact with the water.
For this demonstration we used an E309 rod and used the SMAW process. The rod runs similar to any other drag rod but the work angel has to be exaggerated just a bit. Due to the fact that stainless steel has a lower thermal conductive than steel, it takes a bit more attention to tie in properly. In the video we had 304 stainless as our bottom plate and an A36 mild steel plate on the top. This is a typical fillet weld in a t-joint configuration. In order to get a good tie-in to the stainless plate we run the work angle at roughly 65°-70° angle so that more heat is being placed on the stainless steel. This will help prevent lack of fusion as well as slag inclusions. The electrode runs pretty fluid and travel speeds are similar to an E7018.
We also demonstrate what happens if you use a 45° work angle as if we were running a regular mild steel drag rod such as an E7018. You'll notice that we end up with both lack of fusion and some slag inclusion. It is worth noting that is the configuration had been reversed and the stainless was on top and the mild steel piece was on the bottom, we would then use a work angle of 25° or so and favor the vertical leg tying into the stainless plate.
With a little practice and patience you shouldn't have any problem running this electrode. As with any welding process, make sure you have adequate ventilation. Stainless steel contains hexavalent chromium and can potentially cause health issues. Always make safety the first priority of every job. Until next time, Make Every Weld Better Than Your Last.