Mechanical Properties of Inch Fasteners
Mechanical Properties of Internally Threaded Fasteners
SpecificationASTM A563-Grade 0ASTM A563-Grade AASTM A563-Grade A
Heavy Hex
Material
Nominal Size(in.)1/4 - 1 1/2
Proof Load Stress (psi)Plain
69,000*90,000*100,000*90,000**144,000
coating (1)52,000*68,000*75,000*68,000**
Hardness RockwellMin.B55B68B68
Max.C32C32C32
Grade Identification Marking
Carbon Steel
1/4 - 1 1/21/4 - 4
ASTM A563-Grade C may be
Heavy Hexquenched and
ASTM A563-Grade DH Heavy Hex
Carbon Steel, quenched and tempered
1/4 - 4B78C38
1/4 - 4175,000150,000C24C38
Medium
Heavy HexCarbon Steel
1/4 – 1 1/2
175,000
Over 1 1/21/4 – 5/8
C24C35C35
FNL Grade 9 Thick Hex Nut
C32
180,000
C35
C38C40
Carbon Steel
3/4 – 1 1/2
ASTM A194-Grade 8
Heavy Hex
AISI 3041/4 – 1 1/280,000B60C32
Heavy Hex
AISI 3161/4 – 1 1/280,000B60C32
SAE J995 Grade Identification
GradeMaterial
5
8
Proof
Load Stress (psi)1/4 - 4
109,000**
Carbon steel
105,000*
Over 1 – 1 1/2
94,000**
1/4 – 5/8
carbon or
alloy steel, Over 5/8 – 1150,000quenched &
Over 1 – 1 1/2tempered
Nominal Size(in.)
RockwellHardnessMin.Max.
C32C32
C24C26C26
C32C34C36
Grade Identification
Marking
(1): Galvanize coating refers to nuts that have been plated with a plating or coating of sufficient thickness to require overtapping of the nut to provide assembly: for example hot-dip or mechanical galvanizing.* UNC and 8 UN ** UNF, 12 UN & finer
***When a zinc coated A194 2H nut is supplied, the zinc coating, overtapping, lubrication and rotational capacity testing shall be in accordance with ASTM A563 and the proof stress reduced accordingly. Nuts coated with zinc shall have an asterisk “*” marked after the grade symbol. Nuts coated with cadmium shall have a plus sign “+” marked after the grade symbol.