Why Titanium Demands Exceptional Shielding
Above 400C, titanium begins absorbing oxygen and nitrogen. Above 700C, it reacts violently with nitrogen. Even small amounts of gas absorption (0.1%) can reduce weld ductility by 50% or more. The entire weld zone must be protected until temperature drops below 260C.
Shielding Gas Selection
Primary: 100% Argon (Grade A or better)
- Purity: 99.998% minimum
- Dew point: -51C or lower (max 20 ppm moisture)
- Oxygen: 20 ppm maximum
- Nitrogen: 30 ppm maximum
Never use CO2, nitrogen, oxygen, or hydrogen-containing mixtures for titanium welding.
Trailing Shield Design and Setup
The trailing shield extends argon coverage behind the torch to protect cooling weld metal (260-700C range). Minimum 150mm behind torch centerline. Flow rate: 10-15 L/min. Must cover full weld width plus 25mm on each side.
Back Purge Requirements
Back side must receive equal protection. Methods: sealed chamber, local purge box, purge gas dams, or continuous back purge. Minimum 5 minutes pre-purge. Verify with oxygen analyzer below 20 ppm.
Weld Color as Quality Indicator
| Weld Color | Quality | Interpretation |
|---|---|---|
| Bright silver / straw yellow | Excellent | Minimal oxygen pickup |
| Light gold / pale straw | Acceptable | Very minor pickup |
| Dark gold / bronze / purple | Marginal | Review shielding setup |
| Dark blue | Reject | Re-weld required |
| Gray / white powder | Severe | Gross contamination |
GTAW Parameters for Titanium
| Thickness (mm) | Current (A) | Tungsten (mm) | Filler (mm) | Gas Flow (L/min) |
|---|---|---|---|---|
| 0.5-1.5 | 30-80 | 1.6 | 1.0-1.6 | 8-12 |
| 1.5-3.0 | 80-140 | 2.4 | 1.6-2.4 | 10-15 |
| 3.0-6.0 | 140-220 | 3.2 | 2.4-3.2 | 12-18 |
| 6.0-12.0 | 180-300 | 3.2-4.0 | 3.2 | 15-20 |
Sourcing Titanium Products
CoreMetal Steel supplies titanium pipe, tube, sheet, plate, and welding consumables in all common grades (Grade 1, 2, 5, 7, 9, 12, 23) with full mill certification.
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