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 BD 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. Heavy anchor rods and high-strength studs above the structural bolt range.
Grade BD matches SAE Grade 8 and ASTM A490 on strength in the smaller sizes and keeps going to 4 in.
One of the charts cross-checked here prints the Grade BC figures under the Grade BD heading - a copy-and-paste error in that source. The figures above are the ones the other sources carry.
Frequently asked questions
How strong is a ASTM A354 Grade BD bolt?
Over 1/4 in through 2-1/2 in, ASTM A354 Grade BD requires a minimum tensile strength of 150 ksi (1034 MPa), a minimum yield of 130 ksi (896 MPa) and a proof load of 120 ksi (827 MPa). The requirement changes in the larger sizes - 2 diameter bands are published in all.
What does a ASTM A354 Grade BD head marking look like?
Marked BD on the head.
What is a ASTM A354 Grade BD bolt made of?
Alloy steel, quenched and tempered. Heavy anchor rods and high-strength studs above the structural bolt range.
Does ASTM A354 Grade BD get weaker in larger sizes?
The requirement changes with diameter. 1/4 in through 2-1/2 in: 120 ksi (827 MPa) proof; Over 2-1/2 in through 4 in: 105 ksi (724 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: