GTAW process of Carpenter 20cb3
GTAW process of Carpenter 20cb3
(OP)
I am welding 3/4" up tp 2" schedule 10 Carpenter 20 cb3 with ER320. Does anyone have idea what the black specs of trash that form in the weld puddle and are left on top of the solidified weld are and how they form?
RE: GTAW process of Carpenter 20cb3
A few items to check:
- What gas is being used? Generally, 100% Argon is used with GTAW of Alloy20 (20Cb3)
- Eliminate any contamination from grinders, i.e., get new grinding wheels (Aluminum Oxide not Silicon Carbide).
- Use a large cup to dispense the gas over the area.
- Use an Argon Purge on the backside of the weld.
- Consider using E320LR (Low Residuals).
- Cleanliness is important, do not use crayons to mark.
Here is a link to the Technical Data BLUE SHEET from Allegheny Ludlum Corporation Pittsburgh, PA for Alloy 20 http://www.alleghenyludlum.com/ludlum/pages/products/pdf/al20.pdf
RE: GTAW process of Carpenter 20cb3
RE: GTAW process of Carpenter 20cb3
- Nickel Oxide is black in color. Could the welder be using too much Gas and creating turbulence, hence pulling oxygen into the weld pool?
- Does the Black material react to Nitric acid? (Check for Iron)
- Have you carefully ground out the defect. Is it all on the surface is dispersed throughout?
- If you can get a sample of the black material is it magnetic?
- Take a sample of the black material and put in in a small vial add household ammonia (small amount), shake, doe the ammonia change color? what color? If it turns blue (Royal Blue)it is probally a copper compound.
I wish I had a better answer. It concerns me that it is forming in the weld puddle.
Rich
RE: GTAW process of Carpenter 20cb3
If it forms while welding I'd think it is foreign material.
3/4" Schedule 10 would be pretty tough to weld and control heat input.
Have a good day
G Austin
RE: GTAW process of Carpenter 20cb3
Sincerely
Walt
RE: GTAW process of Carpenter 20cb3
G Austin
RE: GTAW process of Carpenter 20cb3
Seldom
"There's no such thing as a welding problem, just welding puzzles of assorted sizes!"
RE: GTAW process of Carpenter 20cb3
Your description of "black" specks could be construed as a chrome oxide that exhibits itself on the puddle surface in the P4x's when using too high of heat input. I've observed & experienced this phenomenon and have been actually able to move the oxide around on the molten puddle similar to a jumble of sticks with the tip of my filler rod. Though when the puddle is solidified, I personally can't describe the condition as exactly "black specks" but I could understand why somebody might describe them as such.
Seldom
"There's no such thing as a welding problem, just welding puzzles of assorted sizes!"