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Q: I am a welding instructor at the local technical college and have been welding for 30+ years. As part of the shielded metal arc welding (SMAW) courses, we teach welding with E309L stick electrodes in all positions.
I know that welding stringers are recommended whenever using stainless, and we do this for horizontal and overhead.
The problem comes with welding vertical up.
The students cannot seem to get the bead to lie down without spreading the bead wider with a weave technique. As the electrode gets hotter the shorter it gets, the beads start rolling excessively.
We have worked with the current, lowering it until it is entirely too cold. We use 1/8 in. electrodes. I have been using AC rather than DC+ to keep the heat down on the electrode somewhat, but that does not seem to help.
What suggestions do you have about current type, amperage, arc length, angles, speed, and technique?
A: Electrode selection is the first step in welding out of position successfully because not all stainless steel electrodes are designed to weld out of position.
For best operation out of position you should consider a -15 electrode or an appropriate -16 electrode for the alloy being joined.
Te use of AC output from your welding machine has a half positive and half negative cycle with the negative part of the cycle that will melt the electrode faster, resulting in a more convex weld shape.
When welding vertical up on plate use -15 coating and a small triangle weave on the first pass, when the students can produce a suitably flat weld, move them back to stringers.
If you are using 1/8 in. diameter 309-15, the amperage should be about 75 amps for vertical up and about 90 amps for overhead.
Q: Which GTAW filler metal is used to weld A335 P22 and P11 pipe to A387 Gr11 plate?
A: The A335 P22 is a 2 ¼ Cr – 1 Mo material and A335 P11 is 1 ¼ Cr – ½ Mo material being joined to the plate material that is also 1 ¼ Cr – ½ Mo material. With these alloys the rule of thumb is to match the lower alloy material as would be the case with the A335 P22 material to the A387 Gr 11 plate material. In both cases, you could use a “B2” filler metal. The next issue in filler metal selection is the use of post weld stress relief which is not mentioned. If the weld is going to be subjected to a post weld stress relief then use an ER80S-B2 and if there will be no post weld stress relief you should consider ER70S-B2L.
Q: I want to know if you can weld the type of cast aluminum that most Asian automobile wheels are made from. I want to cut a lip off the edge of one rim, and weld it to another. Is this possible? And, if so, what do I need to do this?
A: You should give up on this one. The wheel casting is heat treated to obtain higher strength and you have no way to do this.
That means your weld and its heat affected zone will be significantly weaker than the rest of the cast wheel, perhaps to the point of being dangerous.
If I were you, I’d buy a new wheel.
|This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: email@example.com.|