Selecting the right filler metal - Part 6 SMAW AWS 309L
When welding stainless steel one of the finest rods to use is the AWS E 309L. The 309 is a versatile welding rod. Its capacity to join stainless to stainless, stainless to steel, or steel to steel makes the 309L a favorite rod the job site. The corrosion and wear resistance of the 309L is quite high. It’s often used in the pipe industry to join fittings and valves where corrosive or abrasive material might cause fast wear and damage to the joint. The 309L has considerable slag so it’s a little difficult to use. Attention must be paid to the rod angle or slag will tend to run ahead of the weld. The slide component that makes it difficult control is primarily lime and iron powder. When using a 309L, less amperage is required than other rods. Use approximately 20% less heat than you would with a rod like 7018. Too too much heat will result in a lot of problems, particularly an uncontrollable weld puddle. Many weldors use a stringer bead when welding with the 309L, because of the difficulty and problems the 309 presents. However, the 309L can make some of the most beautiful and aesthetically appealing welds you could possibly make because of the flow qualities of the stainless. Too much heat though will leave you with a molten mess. The tendency of the welding rod to get hotter as the weld progresses is another problem, even if you start within the right amp range. A lot of inexperienced welders will find that the rod gets too hot to weld after it burns about half way down. Stainless heats up rapidly because it has a higher resistance to the flow of heat than regular steel. It also has a habit of drawing the metal up around the weld seam. Prepositioning and restraining the parts is critical. A weld that is started between two pieces of metal that are laying flat on a table will usually result in a “V” shape. By beginning the weld with the two pieces of metal fitted so they make an inverterted “V”, will often offset the draw so that the two pieces of metal or perfectly in line with each other when the weld is finished. Though it is difficult to learn, after a while, the 309L becomes a favorite when toughness, and corrosion resistance is required.