Strain Hardened 303 Free-Machining High-Strength Continuous & Double-End Studs
ASTM A320 Grade B8F Class 2 are made from solution-treated free-machining 303 material that has been strain hardened (Table 1 footnote C), typically by cold drawing the bar (X1.1). These cold-worked 303 studs deliver 125 ksi tensile strength with 100 ksi yield in sizes 3/4 in. [20 mm] and under; minimums fall to 115/80 ksi over 3/4 to 1 in., 105/65 ksi over 1 to 1-1/4 in., and 100/50 ksi over 1-1/4 to 1-1/2 in. (Table 1). B8F Class 2 are marked with a line under the grade symbol (13.1) and are exempt from impact testing only above -325°F [-200°C] (6.2.1.1).
| Grade Symbol | UNS Designation | C, max | Mn, max | P, max | S, max | Si, max | Ni | Cr | Se | |
|---|---|---|---|---|---|---|---|---|---|---|
| ASTM A320 B8F | S30300(303) | Range,% | 0.15 | 2.00 | 0.20 | 00.15, min | 1.00 | 8.0 - 10.0 | 17.0- 19.0 | 0.15-0.35 |
| Product Variation, % Over or Under | 0.01 over | 0.04 over | 0.010 over | 0.20 | 0.05 over | 0.10 | 0.20 | ... | ||
| Grade and Class | Diameter, in. [mm] | Heat Treatment | Tensile Strength, min, ksi [MPa] | Yield Strength, min, ksi [MPa] (0.2 % offset) | Elongation in 2 in. or 50 mm, min, % | Reduction of Area, min, % | Hardness, max |
|---|---|---|---|---|---|---|---|
| B8F : Class 2 | 3/4 [20] and under | carbide solution treated and strain hardened | 125 [860] | 100 [690] | 12 | 35 | 321 HBW or 35 HRC |
| over 3/4 to 1 [20 to 25], incl | 115 [795] | 80 [550] | 15 | 30 | 321 HBW or 35 HRC | ||
| over 1 to 11/4 [25 to 32], incl | 105 [725] | 65 [450] | 20 | 35 | 321 HBW or 35 HRC | ||
| over 11/4 to 11/2 [32 to 40], inclA | 100 [690] | 50 [345] | 28 | 45 | 321 HBW or 35 HRC |
