ASTM A354 covers bolts, studs, and other externally threaded fasteners up to 4” diameter. There are two different grades of bolting strength within A354, Grade BC and Grade BD.
While both grades BC and BD are medium-carbon alloy, quenched and tempered materials, grade BD has a higher yield and tensile strength. The chart below shows the mechanical properties of both materials.
| Grade | Size (in.) | Yield, KSI, min | Tensile, KSI, min | Elong %, min | RA %, min | HRC |
|---|---|---|---|---|---|---|
| BC | 1⁄4" - 21⁄2" | 109 | 125 | 16 | 50 | C26 min C35 max |
| 25⁄8" - 4" | 94 | 115 | 16 | 45 | C22 min C33 max | |
| BD | 1⁄4" - 21⁄2" | 130 | 150 | 14 | 40 | C33 min C39 max |
| 25⁄8" - 4" | 115 | 140 | 14 | 40 | C31 min C39 max |
One key difference between the two grades is that grade BC bolts may be hot-dip galvanized, while ASTM warns against hot-dip galvanizing grade BD bolts.