{"id":8841,"date":"2026-10-02T07:54:05","date_gmt":"2026-10-02T05:54:05","guid":{"rendered":"https:\/\/mfinox.com\/?p=8841"},"modified":"2026-09-25T09:51:14","modified_gmt":"2026-09-25T07:51:14","slug":"alloy-800-800h-and-800ht-which-one-to-choose-for-high-temperatures","status":"publish","type":"post","link":"https:\/\/mfinox.com\/en\/alloy-800-800h-and-800ht-which-one-to-choose-for-high-temperatures\/","title":{"rendered":"Alloy 800, 800H, and 800HT: Which One to Choose for High Temperatures"},"content":{"rendered":" \n

Three designations that differ by a single letter, and a purchasing mistake that comes back to haunt you during operation. Alloy 800, 800H, and 800HT are often treated as commercial variants of the same material, and in a request for quotation, one might see \u201cAlloy 800\u201d specified for an application operating at 750 \u00b0C\u2014where, as specified, that material is not the correct choice. <\/p> \n \n

The difference isn\u2019t a matter of marketing. It lies in three parameters that are controlled differently\u2014 carbon, grain size, aluminum, and titanium<\/strong> \u2014and pertains to a single property: creep<\/strong> resistance, that is, slow and permanent deformation under a constant load at high temperatures. Let\u2019s see what actually changes and how the material is specified in detail, including the standards for fasteners, where Alloy 800 holds a surprise. <\/p> \n \n

One family, three specifications<\/h2> \n \n

This refers to an iron-nickel-chromium<\/strong> alloy containing between 30 and 35% nickel, between 19 and 23% chromium, and no less than 39.5% iron. It is precisely this high iron content that makes it more economical than nickel alloys in the strict sense, while still maintaining resistance to oxidation and carburization at temperatures that austenitic stainless steels cannot withstand. <\/p> \n \n

\n \n \n \n \n \n \n \n
Name<\/th> \nUNS<\/th> \nMaterial<\/th> \n<\/tr> \n<\/thead> \n
Alloy 800<\/td> \nN08800<\/td> \n1.4876<\/td> \n<\/tr> \n
Alloy 800H<\/td> \nN08810<\/td> \n1.4958<\/td> \n<\/tr> \n
Alloy 800HT<\/td> \nN08811<\/td> \n1.4959<\/td> \n<\/tr> \n<\/tbody> \n<\/table> \n
The basic composition is the same; it is the controlled parameters that change.<\/figcaption> \n<\/figure> \n \n

What Really Changes<\/h2> \n \n
\n \n \n \n \n \n \n \n \n \n
<\/th> \nAlloy 800<\/th> \nAlloy 800H<\/th> \nAlloy 800HT<\/th> \n<\/tr> \n<\/thead> \n
Carbon (%)<\/td> \n\u2264 0.10<\/td> \n0.05 \u2013 0.10<\/td> \n0.06 \u2013 0.10<\/td> \n<\/tr> \n
Grain Size<\/td> \nnot expired<\/td> \nASTM 5 or coarser<\/td> \nASTM 5 or coarser<\/td> \n<\/tr> \n
Aluminum (%)<\/td> \n0.15 \u2013 0.60<\/td> \n0.15 \u2013 0.60<\/td> \n0.15 \u2013 0.60<\/td> \n<\/tr> \n
Titanium (%)<\/td> \n0.15 \u2013 0.60<\/td> \n0.15 \u2013 0.60<\/td> \n0.15 \u2013 0.60<\/td> \n<\/tr> \n
Sum of Al + Ti (%)<\/strong><\/td> \nnot expired<\/td> \nnot expired<\/td> \n0.85 \u2013 1.20<\/strong><\/td> \n<\/tr> \n<\/tbody> \n<\/table> \n
Typical specification values. Always verify these on the casting certificate. <\/figcaption> \n<\/figure> \n \n

The three lines that matter, listed in order of importance:<\/p> \n\r\n