Titanium tells you how well it was welded. Titanium weld color is a direct readout of how much air reached the hot metal while it cooled, and it’s the first thing an inspector looks at. This guide explains what each color means, which ones are usually acceptable, and what causes the bad ones.
Need titanium welded properly? Weld Creations is an AWS D17.1 certified shop in Glendora, California, TIG welding titanium with trailing shields and full back purging. See titanium welding or request a quote.
Why titanium changes color
Above roughly 800°F (425°C), titanium reacts eagerly with oxygen and nitrogen in the air. If shielding gas doesn’t cover the weld and the hot metal behind it until it cools, an oxide layer forms. Thin oxide layers produce interference colors, the same effect that makes oil on water look rainbow-colored. The thicker the oxide, the further the color shifts, and the more oxygen and nitrogen have dissolved into the metal underneath.
That’s the key point: the color isn’t a cosmetic issue, it’s evidence. Oxygen and nitrogen in solution make titanium harder and more brittle, and that happens in the metal, not just on it.
The color chart
Acceptance criteria come from your specification, not from a chart. AWS D17.1 and customer specifications set out which colors are acceptable for each weld class, and they don’t all agree. Put the acceptance criteria on the drawing so the shop and the inspector are judging against the same standard. For what D17.1 covers, see our AWS D17.1 guide.
What causes bad color
When a titanium weld comes out blue or gray, the cause is almost always shielding or cleanliness:
Shielding problems
- Gas flow too low, or so high it becomes turbulent and pulls in air.
- No trailing shield. The torch moves on, and the metal behind it is still hot enough to react.
- No back purge, so the root side oxidizes even when the face looks right.
- Post-flow cut short. Gas must keep flowing after the arc stops until the metal cools.
- A standard nozzle instead of a gas lens, giving a smaller, more turbulent envelope.
- Leaks in the torch, hoses or fittings, which draw air into the gas stream. Ordinary rubber hose can also let air permeate, which is why dedicated argon-rated hose matters.
- Moisture or contamination in the gas line, or a cylinder that’s run too low.
Cleanliness problems
- Oil, grease, fingerprints or cutting fluid left on the joint.
- Surface oxide not removed before welding.
- Tools shared with steel, leaving iron contamination.
- Filler wire that has been handled with bare hands or stored uncovered.
How to get silver welds
- Prepare the joint properly. Degrease with a clean solvent such as acetone, remove surface oxide with carbide tooling or stainless brushes used only on titanium, and weld soon after cleaning.
- Handle with clean gloves. Fingerprints are contamination.
- Use a gas lens and the right cup size to create a broad, laminar gas envelope.
- Add a trailing shield sized for the joint, so the cooling weld stays covered.
- Back purge every full-penetration joint and closed section.
- Set generous post-flow and leave the torch over the weld until it cools.
- Check the gas system for leaks, and use hose intended for shielding gas.
- For complex parts, weld in a purge chamber, where the whole part sits in an inert atmosphere.
What to do about a discolored weld
- Light straw within your specification: usually acceptable as is.
- Darker straw or purple on non-critical welds: check the specification. Some allow removal of the discoloration and re-inspection.
- Blue, gray or white: the metal has absorbed oxygen and nitrogen. Polishing changes the appearance without restoring the properties. The affected weld is removed and rewelded, with the shielding problem fixed first.
If a supplier offers to “clean up” a gray weld, that’s a sign to look elsewhere.
Getting titanium welded right
Weld Creations TIG welds commercially pure titanium and Ti-6Al-4V with torch, trailing and back-purge shielding, dedicated titanium tooling and clean-handling discipline. We’re AWS D17.1 certified, which covers titanium alloys. Tell us the grade, the weld class and the acceptance criteria on your drawing, and we’ll weld and inspect to it. See titanium welding, aerospace welding or our capabilities.