Cutting Titanium, Inconel & Exotic Alloys
Exotic aerospace alloys — titanium, Inconel, Hastelloy, and other nickel-based superalloys — present unique challenges for laser cutting. Their high melting points, low thermal conductivity, and reactivity with oxygen demand specialized parameters, inert gas shielding, and careful HAZ management.
Quick Answer
Titanium (Ti-6Al-4V) cuts well with 4–8kW fiber lasers using argon assist gas at 15–20 bar. The critical concern is preventing alpha-case formation — an oxygen-enriched brittle layer that reduces fatigue life by up to 50%. Inconel 718 is slower to cut due to its extreme high-temperature strength, requiring higher power density and specialized parameter optimization.
Titanium Alloy Cutting Parameters
| Alloy | Thickness | Power | Speed | Gas / Pressure | Focus |
|---|---|---|---|---|---|
| Ti-6Al-4V | 1.0mm | 4kW | 8–12 m/min | Ar / 18 bar | -0.5mm |
| Ti-6Al-4V | 2.0mm | 6kW | 4–7 m/min | Ar / 20 bar | 0mm |
| Ti-6Al-4V | 3.0mm | 8kW | 2–4 m/min | Ar / 22 bar | +1mm |
| Ti-6Al-4V | 5.0mm | 10–12kW | 0.8–2 m/min | Ar / 25 bar | +2mm |
| CP Ti Grade 2 | 1.5mm | 4kW | 6–10 m/min | N₂ / 16 bar | -0.5mm |
Alpha-Case Prevention
Alpha-case is an oxygen-enriched layer that forms on titanium above 500°C. It is brittle and reduces fatigue life by 30–50%. Prevention requires:
- • Argon assist gas with purity ≥99.998% (Grade 4.8)
- • Trailing shield gas for parts thicker than 2mm
- • Post-cut inspection: check for blue/gray discoloration (indicator of alpha-case)
- • Chemical milling removal if alpha-case detected (0.025mm stock removal per side)
Nickel Superalloy Cutting Parameters
| Alloy | Thickness | Power | Speed | Gas / Pressure | Key Challenge |
|---|---|---|---|---|---|
| Inconel 718 | 1.0mm | 4kW | 5–8 m/min | N₂ / 18 bar | Dross adherence |
| Inconel 718 | 2.0mm | 6kW | 2.5–5 m/min | N₂ / 20 bar | Recast layer control |
| Inconel 625 | 1.5mm | 4–6kW | 4–7 m/min | N₂ / 18 bar | Edge oxidation |
| Hastelloy X | 1.0mm | 4kW | 4–6 m/min | Ar / 20 bar | Micro-crack in HAZ |
| Waspaloy | 2.0mm | 6kW | 2–4 m/min | Ar / 22 bar | Strain-age cracking |
Nickel superalloys retain strength at high temperatures, making them slower to cut than titanium at equivalent thickness. The recast layer (re-solidified metal at cut edge) must be controlled to <0.025mm for most aerospace specifications.
Assist Gas Selection & Shielding Strategy
Argon — Premium Inert Shield
- • When: Flight-critical titanium, Hastelloy, all nickel superalloys
- • Why: Heavier than air (1.38× density), better shielding coverage
- • Purity: ≥99.998% (Grade 4.8) for titanium
- • Pressure: 18–25 bar typical
- • Cost: 3–5× nitrogen, justified for aerospace parts
Nitrogen — Cost-Effective Option
- • When: CP titanium, stainless steels, non-flight-critical parts
- • Why: Lower cost, adequate for less reactive alloys
- • Purity: ≥99.999% (Grade 5.0) for aerospace
- • Pressure: 14–20 bar typical
- • Limitation: Can form titanium nitride on Ti alloys at high temp
Related Topics
Disclaimer: Parameters for exotic alloys are highly sensitive to specific heat treatment condition, grain size, and surface finish. These are starting points based on published data. Formal process qualification per your customer's specification is mandatory for flight hardware.