Mechanical requirements by diameter
Inch grades are published in ksi and metric classes in MPa. The other column on every row is a conversion at 1 ksi = 6.894757 MPa, rounded to the nearest whole unit - it is arithmetic on the published figure, not a second published figure.
The head marking
Marked BC on the head.
The grade letters stamped in full.
Count the radial lines and add two. That rule identifies exactly two grades - SAE Grade 5 with three lines and SAE Grade 8 with six - and it fails everywhere else. Grades 1, 2 and 4 carry no marking at all, so an unmarked head is not evidence of Grade 2; it is evidence of nothing, and unmarked hardware that meets no standard looks exactly the same. ASTM grades are stamped with the specification (A325, A490, BC, BD, 307A) rather than lines, and metric classes are stamped with the class number. Four marking systems share one bin.
Material and where it is used
Alloy steel, quenched and tempered. Anchor rods, long studs, high-strength fasteners above the SAE size range.
Covers diameters up to 4 in, well beyond the 1-1/2 in ceiling of SAE J429, which is why anchor rods and long studs are specified to A354 rather than to a Grade number.
Frequently asked questions
How strong is a ASTM A354 Grade BC bolt?
Over 1/4 in through 2-1/2 in, ASTM A354 Grade BC requires a minimum tensile strength of 125 ksi (862 MPa), a minimum yield of 109 ksi (752 MPa) and a proof load of 105 ksi (724 MPa). The requirement changes in the larger sizes - 2 diameter bands are published in all.
What does a ASTM A354 Grade BC head marking look like?
Marked BC on the head.
What is a ASTM A354 Grade BC bolt made of?
Alloy steel, quenched and tempered. Anchor rods, long studs, high-strength fasteners above the SAE size range.
Does ASTM A354 Grade BC get weaker in larger sizes?
The requirement changes with diameter. 1/4 in through 2-1/2 in: 105 ksi (724 MPa) proof; Over 2-1/2 in through 4 in: 95 ksi (655 MPa) proof. Quoting one figure across the whole range gets part of it wrong.
What this section covers
Twenty-two grades and classes: the SAE J429 inch grades, five ASTM specifications and the ISO 898-1 property classes. It is not every grade in circulation. Stainless classes (ISO 3506 A2 and A4, ASTM F593), the ASTM A193 and A320 high and low temperature grades, ASTM F1554 anchor rod grades and SAE grades 3, 5.1 and 8.1 are not carried here.
Where these figures come from
Dimensions are as defined by ASTM A354. This site is an independent reference and is not affiliated with, endorsed by or approved by any standards body.
Every value on this page was cross-checked against 4 independent published sources:
ASTM A354 Grade BC yield strength above 2-1/2 in: 99 ksi (grades-anchorrods) against 99 ksi (grades-wikipedia) against 94 ksi (grades-allthreadrod). 99 ksi is printed - two of the three sources give it, and the third is otherwise identical to the second, which points to a typing error rather than a different specification.