AISI/SAE Designation

Add one script tag to your page:

<div data-alloyfyi="glossary" data-slug="aisi-sae-designation"></div>
<script src="https://cdn.jsdelivr.net/npm/alloyfyi-embed@1/dist/embed.min.js" defer></script>

Embed as an iframe:

<iframe src="https://alloyfyi.com/iframe/glossary/aisi-sae-designation/?style=modern&theme=light" width="420" height="400" frameborder="0" loading="lazy" style="border:0;border-radius:10px;max-width:100%"></iframe>

Paste the URL in WordPress, Medium, or Ghost:

https://alloyfyi.com/hi/glossary/aisi-sae-designation/

Web Component:

<alloyfyi-glossary slug="aisi-sae-designation"></alloyfyi-glossary>
<script src="https://cdn.jsdelivr.net/npm/alloyfyi-embed@1/dist/embed.min.js" defer></script>

Testing & Standards

Definition

A four-digit numbering system developed by the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE) to classify carbon and alloy steels by composition. The first two digits indicate the alloy family and the last two (or three) digits the nominal carbon content in hundredths of a percent.

Detailed Explanation

For example, AISI 1045 is a plain carbon steel (10xx series) with 0.45 wt% carbon; AISI 4140 is a chromium-molybdenum alloy steel (41xx series) with 0.40 wt% carbon. The system provides a shorthand understood throughout North American industry for specifying steel grade, simplifying material procurement and comparison. Stainless steels use a separate three-digit AISI numbering (e.g., 304, 316, 410), though EN/ISO designations are increasingly used internationally.