There are many ways to write stainless steel material codes (grades), among which 304, 304L, 316L, etc. refer to American standard stainless steel grades.
For common American standard stainless steel material composition standards, refer to ASTM A240/A240M-15a Standard Specification for Chromium and Chromium Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and General Applications
[Remarks] ASTM A240/A240M-15a is consistent with ASTM A240/A240M-18 for the composition of stainless steel materials listed in this document.
The composition specifications of 304, 304L, 316L, 321 and 301, 309S, 310S, 2205 and 2507 stainless steels are listed below:
American Standard Stainless Steel Material Composition Table
| UNS No | Grade | C | Mn | P | S | Si | Cr | Ni | N | Mo | Ti |
| S30400 | 304 | 0.07 | 2 | 0.045 | 0.03 | 0.75 | 17.5-19.5 | 8.0-10.5 | 0.10 | ||
| S30403 | 304L | 0.03 | 2 | 0.045 | 0.03 | 0.75 | 17.5-19.5 | 8.0-12.0 | 0.10 | ||
| S31603 | 316L | 0.03 | 2 | 0.045 | 0.03 | 0.75 | 16.0-18.0 | 10.0-14.0 | 0.10 | 2-3 | |
| S32100 | 321 | 0.08 | 2 | 0.045 | 0.03 | 0.75 | 17.0-19.0 | 9.0-12.0 | 0.10 | 0.63-0.9 |
Note:
- 1. The unit is percentage, i.e. “%”;
- 2. Except for the indicated range, the components listed in the table are the maximum values.
American Standard Stainless Steel Material Composition Table
Source: ASTM A240/A240M-15a
| UNS No | Grade | C | Mn | P | S | Si | Cr | Ni | N | Mo | Ti |
| S30100 | 301 | 0.15 | 2 | 0.045 | 0.03 | 1 | 16.0-18.0 | 6.0-8.0 | 0.10 | ||
| S30908 | 309S | 0.08 | 2 | 0.045 | 0.03 | 0.75 | 22.0-24.0 | 12.0-15.0 | – | ||
| S31008 | 310S | 0.08 | 2 | 0.045 | 0.03 | 1.5 | 24.0-26.0 | 19.0-22.0 | – | ||
| S32205 | 2205 | 0.03 | 2 | 0.03 | 0.02 | 1 | 22.0-23.0 | 4.5-6.5 | 0.14-0.2 | 3-3.5 | |
| S32750 | 2507 | 0.03 | 1.2 | 0.035 | 0.02 | 0.8 | 24.0-26.0 | 6.0-8.0 | 0.24-0.32 | 3-5 |
Note:
- 1. The unit is percentage, i.e. “%”;
- 2. Except for the indicated range, the components listed in the table are the maximum values.
It can be seen from the above table that the chemical element content of American standard 304 is similar to that of national standard 06Cr19Ni10 (unified number code: S30408) and Japanese standard SUS304;
The chemical composition of American standard 316L stainless steel is similar to that of national standard 022Cr17Ni12Mo2 (unified number code: S31,603) and Japanese standard SUS316L.
