Incoloy 800 Welding Procedure
1. Preparation:
Clean base metal thoroughly to remove contaminants such as oil, grease, and oxides.
Preheat is usually not required, but for thick sections (>25 mm), preheating to around 150°C (300°F) can help reduce thermal stress.
2. Welding Methods:
Suitable welding methods: TIG (GTAW), MIG (GMAW), SMAW (Stick), and Plasma welding.
Use filler metals compatible with Incoloy 800, such as ERNiCr-3 (Inconel 82) or ERNiCr-4 (Inconel 625) for optimal corrosion and mechanical properties.
3. Interpass Temperature:
Keep interpass temperature below 260°C (500°F) to avoid carbide precipitation and maintain corrosion resistance.
4. Heat Input:
Use moderate heat input to avoid grain growth and cracking.
5. Post-Weld Heat Treatment (PWHT):
Generally, PWHT is not required for Incoloy 800.
If PWHT is applied, typical stress relief is at 870–950°C (1600–1740°F) for 1–2 hours.
6. Shielding Gas:
Use high-purity argon or argon-helium mixtures to protect the weld pool.
Additional Tips
Avoid rapid cooling to minimize residual stresses.
Control welding parameters to prevent hot cracking.
For critical applications, perform welding procedure qualification testing.
