Grade markings are standardized symbols denoting the combination of the fastener's base material, its strength properties, its performance capabilities, and the engineering standard against which it is produced.
Markings on bolts and screws are usually located on the top of their heads; those on studs on their ends; and on nuts on their top face.
BOLTS
|
TENSILE & YIELD STRENGTH BOLTGUIDE |
|
Material |
Diameter |
Minimum PSI
Tensile Strength |
Minimum PSI
Yield Strength |
|
Grade 2 Steel |
1/4" to 3/4" |
74,000 |
57,000 |
|
|
7/8" to 1-1/2" |
60,000 |
36,000 |
|
|
1 5/8" to 4" |
60,000 |
-- |
|
Grade 5 Steel |
1/4" to 1" |
120,000 |
92,000 |
|
|
1 1/8" to 1 1/2" |
105,000 |
81,000 |
|
|
1 5/8" to 3" |
90,000 |
58,000 |
|
Grade 8 Steel |
1/4" to 1 1/2" |
150,000 |
130,000 |
|
|
1 5/8” & Above |
-- |
-- |
|
18-8 Stainless Steel |
1/4” to 1 1/2" |
75,000 |
30, 000 |
|
316 Stainless Steel |
1/4" to 1 1/2" |
75,000 |
30,000 |
|
400 Monel |
1/4" to 1 1/2" |
75,000 |
30,000 |
|
Brass |
All |
57,000 |
-- |
|
Silicone Bronze |
All |
75,000 |
45,000 |
|
2024 Aluminum |
All |
75,000 |
11,000 |
|
Tensile Stress Area |
|
Diameter |
UNC |
UNF |
|
1/4" |
.0318 |
.0364 |
|
5/16” |
.0524 |
.0580 |
|
3/8” |
.0775 |
.0878 |
|
7/16” |
.1063 |
.1187 |
|
1/2" |
.1419 |
.1599 |
|
5/8” |
.226 |
.256 |
|
3/4" |
.334 |
.373 |
|
7/8” |
.462 |
.509 |
|
1” |
.606 |
.663 |
|
1 1/4" |
.969 |
1.073 |
|
1 1/2" |
1.405 |
1.581 |
NOTE:
(The values listed are for reference purposes only. Check with an engineer for job site applicable loads.)
STAINLESS STEEL: 304, 316, 410
|
GRADE |
GENERAL
DESCRIPTION OF MATERIAL |
SPECIFICATIONS
COVERING RAW
MATERIALS
REQUIREMENTS |
CHEMICAL COMPOSITION
(MIN / MAX LIMITS GIVEN) |
|
|
C |
Mn |
P |
S |
Si |
Cu |
Mo |
NI |
Cr |
other |
|
303 |
Austenitic Stainless Steel |
ASTM A276 TYPE 303
QQ-N-764 CLASS 303
AISI 303 |
0.15 |
2.00 |
0.20 |
.015
min |
1.00 |
-- |
.060 |
8.00
To
10.00 |
17.00
To
19.00 |
-- |
|
304 |
Austenitic Stainless Steel |
ASTM A276 TYPE 304
QQ-S-763 CLASS 304
AISI 304 |
0.08 |
2.00 |
0.045 |
0.030 |
1.00 |
-- |
-- |
8.00
TO
12.00 |
18.00
TO
20.00 |
-- |
|
316 |
Austenitic Stainless Steel |
ASTM A276 TYPE 316
QQ-S-763 CLASS 316
AISI 316 |
0.06 |
2.00 |
0.045 |
0.030 |
1.00 |
-- |
2.00
To
3.00 |
10.00
To
14.00 |
16.00
To
18.00 |
-- |
|
410 |
Martensitic
Stainless Steel |
ASTM A276 TYPE 410
QQ-S-763 CLASS 410
AISI 410 |
0.15 |
1.00 |
0.040 |
0.030 |
1.00 |
-- |
-- |
-- |
11.50
To
13.50 |
-- |
Legend:
ASTM – American Society for Testing and Materials
AISI – American Iron and Steel Institute
QQ-X-XXX – Federal Government
Stainless steel fastener materials are identified as the B8 class of alloys and are identified in the ASTM Specification A193/193M (Standard Specifications for Alloy Steel and Stainless Steel Bolting materials for high temperature service).
A typical of the austenitic group is Type 304, which contains nominally 18% chromium and 8% nickel; hence the 18-8 name.(For further guidance on material selection, consult with an engineer.) 
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