Selecting the right filler metal - Part 5 SMAW E 7018
The E7018 is probably the most revered welding rod in the industry. With the reverence it commands, a lot of people jump at the chance to use it. It's a master of structural steel welding and makes a near perfect weld in skilled hands. The problem is that while it offers the potential of a strong, high quality weld, special care must be taken to preserve its low hydrogen properties that give it the qualities it has. Many of the new people interested in learning to weld are not aware of the storage and handling requirements it has to get the most out of the rods. The low hydrogen properties that prevent weld problems like under bead cracking are lost if moisture enters the rod. Moisture ingresses fairly rapidly into the iron powder and titania flux so the rods must be perpetually heated to hold moisture at bay. All 7018 rods should be kept in a special oven to keep them dry. They also should be purchased in a vacuum sealed container. Many companies will sell them in cardboard boxes or in plastic containers. Unless the welding electrodes are baked at 600 degrees F for several hours, they are not considered safe for critical work. E7018 have several suffix designations which indicate the varying degrees of moisture resistance. Regular non suffix rods are considered acceptable for use out of the oven for only 4 hours. Welding rods that see more time than that out of the oven should be discarded or rebaked at 600 degrees (depending upon exact manufacturer and code requirements). The suffix designation of HR4 allows the stick electrodes to be held out up to 8 hours, again depending upon exact code requirements. Either way, the rods should be stored in an airtight container while away from the oven. 7018 rods can be used with AC “buzz” boxes, though arc starting is much more difficult, and sticking can become an issue. Additionally, higher amperage is required. Reverse polarity (DCEP) is best. A special rod is produced with the designation of 7018 AC that works much better with the cheap transformer welders. However storage requirements are not changed, and it’s unlikely that most people with “buzz” boxes will have the storage ovens required to keep the 7018 at its best. There is not much advantage to using a moisture rich 7018 over another rod like the 7014. Ductility may be a little better, but underbead cracking becomes a problem. For the added cost and additional storage requirements, the 7018 is typically not the best rod choice for most hobbyists and small repair shops. Larger shops do have rod ovens and can buy large, 50lb sealed containers which make it a more economical choice. However for the average user, not doing code work in the construction or pipe industry, the 7014 may be a better choice.