Differences between Alloy 800, 800H and 800HT
Alloy 800, 800H and 800HT are all belong to Incoloy Alloy Series, and the below shows the differences of them.
What is Incoloy material?
INCOLOY is a registered trademark of The International Nickel Co.(INCO was purchased by the Brazilian mining company Vale in 2006).
INCOLOY is a nickel-chromium alloy, Solid solution high-strength austenitic nickel-iron-chromium alloy.
The alloy is designed to antioxidize and carbonize at temperatures. There are many grades, including Incoloy800, Incoloy800h, Incoloy800HT, Incoloy825, Incoloy840, Incoloy901, Incoloy925, INCOLOY20, INCOLOY330, INCOLOY 25-6MO etc.
The ASME/ASTM grade of Incoloy materials: UNS N08800, N08810, N08811.
I. Element Differences
II. Working Temperature
For alloy800, the temperature is recommended to be under 1100°F (593°C). As for 800HT (N08811), the temperature usually is recommended to be over 1100°F (593°C).
Since high content of carbon, aluminum and titanium can greatly improve the creep resistance at high temperature, different contents of aluminum and titanium make 800, 800H and 800HT be applied differently in their working temperature.
III. Mechanical Property Difference
IV. Grain and Hardness Requirements
The average grain size of UNS N08810 and UNS N08811 is 5.0 or above.
In the early days, Alloy 800, 800H and 800HT are all classified as nickel-base alloy series, and their standard were ASTM B409 and ASME SB409.
Due to their low nickel content (Standard one shall contain 30 to 35% nickel, and the typical content is 30%), they have been removed from the nickel-based alloy category. For those who want to know more about these three alloys, you are suggested to read ASTM A240 and ASME SA240.
And please note that the export and import tax of above three materials follow with stainless-steel standard.