Material Classification System
| Group | Class Numbers | Minimum Properties¹ | |
|---|---|---|---|
| % IACS² | Hardness³ | ||
| GROUP A | 1 | 80 | 65 HRB |
| 2 | 75 | 75 HRB | |
| 3 | 45 | 90 HRB | |
| 4 | 20 | 33 HRC | |
| GROUP B | 10 | 45 | 72 HRB |
| 11 | 40 | 94 HRB | |
| 12 | 35 | 98 HRB | |
| 13 | 30 | 69 HRA | |
| 14 | 30 | 85 HRB | |
| GROUP C | 20 | 75 | 75 HRB |
| 21 | 92 | 62 HRB | |
| 22 | 87 | 68 HRB | |
Notes:
1. Round rod fully heat treated and cold worked up to 1 in (25mm) diameter.
2. %IACS at 68°F (International Alloy Copper Standard).
3. HRB=Rockwell Hardness Scale B; HRC = Rockwell Hardness Scale C; HRA = Rockwell Hardness Scale A.
Reference:
American Welding Society Publication J1.3