Strain Hardened 304 Stainless Steel High-Strength Continuous & Double-End Studs
ASTM A320 Grade B8 Class 2 undergo cold strain hardening to achieve significantly elevated mechanical properties for demanding bolting applications. These 304 stainless steel studs deliver 125 ksi tensile strength and 100 ksi yield strength in diameters up to 3/4 inch, providing superior clamping force in flanged connections. Minimums fall with size: 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), and strain-hardened material may not show uniform properties through the cross section above 3/4 in. [20 mm]. B8 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 | |
|---|---|---|---|---|---|---|---|---|---|
| ASTM A320 B8 | S30400(304) | Range,% | 0.08 | 2.00 | 0.045 | 0.030 | 1.00 | 8.0-11.0 | 18.0 - 20.0 |
| 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 |
|---|---|---|---|---|---|---|---|
| ASTM A320 B8 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 |
