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