A Comprehensive Guide to Nickel-Based Superalloys: Incoloy 800 (UNS N08800/W.Nr. 1.4876)
In the world of advanced materials, nickel-based superalloys have carved out a significant niche due to their exceptional properties and wide range of applications. One such exceptional alloy is Incoloy 800, renowned for its outstanding resistance to high temperatures, corrosion, and pressure. This comprehensive guide will delve into the fascinating world of Incoloy 800, exploring its composition, properties, applications, and benefits.
What is Incoloy 800?
Designated as UNS N08800 or DIN W.Nr. 1.4876, Incoloy 800 (also known as "Alloy 800") is an iron-nickel-chromium alloy that offers good strength and excellent resistance to oxidation and carburization in high temperature atmospheres. It also exhibits excellent resistance to corrosion in a variety of aqueous environments and resistance to chloride stress corrosion cracking. Incoloy 800 alloy can maintain a stable austenite structure when exposed to high temperature for a long time, because it does not form brittle sigma phase after long exposure at 1200°F [649°C]. It is mainly used in petrochemical process pipelines, heat exchangers, carburizing equipment, heating element sheaths, nuclear steam generator pipelines, etc.
Incoloy 800 (UNS N08800) has a high chromium content and sufficient nickel content, so it has high high temperature corrosion resistance and is widely used in industry. It has excellent resistance to stress corrosion cracking in chlorides, low concentration NaOH aqueous solutions and high temperature and high pressure water, so it is used to manufacture stress corrosion cracking resistant equipment. The corrosion resistance is better than that of general austenitic stainless steel and Inconel 600 alloy; in the manufacture of corrosion-resistant stress cracking equipment, it is better than Inconel 600 and Monel 400.
Hot working of Incoloy 800 (N08800) alloy:
(1) The temperature range is 1200℃-950℃, and the cooling method is water quenching or rapid air cooling.
(2) In order to obtain the best performance and creep resistance, solid solution treatment should be carried out after hot working.
(3) The material can be directly sent into a furnace heated to 1200℃. After sufficient insulation time, it can be quickly discharged and heat treated within the specified temperature range. When the material temperature drops below the heat treatment temperature, it needs to be reheated.
Cold working of Incoloy 800 (N08800) alloy:
(1) The work hardening rate is greater than that of austenitic stainless steel, so it is necessary to select processing equipment. The cold-worked material should be in a solid solution heat treatment state, and intermediate annealing should be carried out when the cold working amount is large.
(2) If the amount of cold working is greater than 10%, the workpiece needs to be treated with secondary solution.
Incoloy 800 (N08800) alloy welding process:
Suitable for welding with the same metal material or other metal metals using any traditional welding process, such as tungsten inert gas shielded welding, plasma arc welding, manual sub-arc welding, metal inert gas shielded welding arc welding, MIG welding, pulse arc welding is the first choice. If manual arc welding is used, it is recommended to use (Ar+He+H2+CO2) as the shielding gas.
