Bolt Grade Markings and Strength Chart
|
Head Markings |
Grade or Class |
Material |
(Inches) |
Mechanical Properties |
|
Proof
Load
(psi) |
Minimum Yield Strength
(psi) |
Minimum Tensile Strength
(psi) |
|
American Bolts |
|
No Markings |
Grade
2 |
Low or
Medium Carbon Steel |
1/4
thru 3/4 |
55,000 |
57,000 |
74,000 |
|
Over
3/4 thru 1-1/2 |
33,000 |
36,000 |
60,000 |
|
3 Radial Lines
|
Grade
5 |
Medium
Carbon Steel, Quenched and Tempered |
1/4
thru 1 |
85,000 |
92,000 |
120,000 |
|
Over 1
thru 1-1/2 |
74,000 |
81,000 |
105,000 |
|
6 Radial Lines |
Grade
8 |
Medium
Carbon Alloy Steel, Quenched and Tempered |
1/4
thru 1-1/2 |
120,000 |
130,000 |
150,000 |
|
Stainless markings vary. Most stainless is non-magnetic |
18-8
Stainless |
Steel
alloy with 17-19% Chromium and 8-13% Nickel |
1/4
thru 5/8 |
|
40,000 Min. 80,000 – 90,000 Typical |
100,000 – 125,000 Typical |
|
3/4
thru 1 |
|
40,000
Min. 45,000 – 70,000 Typical |
100,000 Typical |
|
Above
1 |
|
80,000
– 90,000 Typical |
|
Metric Bolts |
|
8.8 |
Class
8.8 |
Medium
Carbon Steel, Quenched and Tempered |
All
Sizes thru 1-1/2 |
85,000 |
92,000 |
120,000 |
|
10.9 |
Class
10.9 |
Alloy
Steel, Quenched and Tempered |
All
Sizes thru 1-1/2 |
120,000 |
130,000 |
150,000 |
|
Stainless markings vary. Most stainless is non-magnetic |
A-2
Stainless |
Steel
alloy with 17-19% Chromium and 8-13% Nickel |
1/4
thru 5/8 |
|
40,000 Min. 80,000 – 90,000 Typical |
100,000 – 125,000 Typical |
|
3/4
thru 1 |
|
40,000
Min. 45,000 – 70,000 Typical |
100,000 Typical |
|
Above
1 |
|
80,000
– 90,000 Typical |
|
Tensile Strength: The maximum load in tension (pulling apart) which
a material can withstand before breaking or fracturing.
Yield
Strength: The maximum load at which a
material exhibits a specific permanent deformation
Proof Load:
An axial tensile load which the product must withstand
without evidence of any permanent set. |
|
