Selecting the right filler - GTAW ER70S-6
A good choice for almost any mild steel TIG application is the ER 70S-6 filler rod. It's reputation is well deserved thanks to the high deoxidizer content of the filler metal. The overall melting and wetting characteristics are unparalleled, especially on less than ideal metal, where rust or other contamination may be a concern. The first thing you'll notice is how easily the metal “wicks” to the sides of the puddle and joins itself to the parent metal. As the rod moves along the ripple pattern or "stack of dimes" look is very easy to achieve, whether you are free-handing or walking the cup. Unless chrome moly is being welded, most people never deviate from using the 70S-6. It is also resistant to undercutting because of its filling and wetting characteristics. This makes welding out of position much easier even though the puddle may seem to be more fluid. When compared directly to the ER 70S-2, results are very similar. However, the surface of the weld may have a slightly glazed look at points where the deoxidizers have done their job and floated the contaminants out on top to form a spotty glass like slag. The primary component of this slag is silicone, so it removes easy. Upon wire brushing, the metal will be shiny as a new nickel. However, if left untouched and another pass is made, the slag can be trapped under the metal and an defective weld can result. Whenever working with the ER 70S-2, make sure all traces of the glass like slag have been removed. It’s simple enough to do, and takes very little time to make a perfect weld.