ASTM A 307 Carbon Steel Bolts and Studs

ASTM A307 Specification for Carbon Steel Bolts and Studs, 60 000 PSI Tensile Strength

Fastener Grades and Description

Grade A Grade B Grade C
Bolts and studs having a minimum tensile strength of 60 ksi (414 MPa) and intended for general applications Bolts and studs having a tensile strength of 60 to 100 ksi (414 to 690 MPa) and intended for flanged joints in piping systems with cast iron
flanges		 Nonheaded anchor bolts, either bent or straight, having properties conforming to Specification A 36 (tensile strength of 58 to 80 ksi (400
to 550 MPa)) and intended for structural anchorage purposes

Chemical Requirements for Grades A and B Bolts and Studs

Heat Analysis Product Analysis
Carbon, max 0.29 0.33
Manganese, max 0.90 0.93
Phosphorus, max 0.04 0.041
Sulfur, max
        Grade A 0.15 A
        Grade B 0.05 0.051
A Resulfurized steel is not subject to rejection based on product analysis for sulfur.

Hardness Requirements for Bolts and Studs

Grade Length, in. Hardness A
Brinell Rockwell B
min max min max
A Less than 3 x 3 dia B 121 241 69 100
3 x 3 dia and longer . . . 241 . . . 100
B Less than 3 x 3 dia B 121 212 69 95
3 x 3 dia and longer . . . 212 . . . 95
C All No hardness required

Tensile Requirements for Full-Size Bolts and Studs

Bolt Size,
in.		 Threads
per inch		 Stress
Area, A
in.2		 Tensile Strength, lbf B
Grade A, 
min C		 Grade B
min D max D
1⁄4 20 0.0318 1 900 1 900 3 180
5⁄16 18 0.0524 3 100 3 100 5 240
3⁄8 16 0.0775 4 650 4 650 7 750
7⁄16 14 0.1063 6 350 6 350 10 630
 
1⁄2 13 0.1419 8 500 8 500 14 190
9⁄16 12 0.182 11 000 11 000 18 200
5⁄8 11 0.226 13 550 13 550 22 600
3⁄4 10 0.334 20 050 20 050 33 400
7⁄8 9 0.462 27 700 27 700 46 200
 
1 8 0.606 36 350 36 350 60 600
11⁄8 7 0.763 45 800 45 800 76 300
11⁄4 7 0.969 58 150 58 150 96 900
13⁄8 6 1.155 69 300 69 300 115 500
 
11⁄2 6 1.405 84 300 84 300 140 500
13⁄4 5 1.90 114 000 114 000 190 000
2 4˝ 2.50 150 000 150 000 250 000
21⁄4 4˝ 3.25 195 000 195 000 325 000
  
21⁄2 4 4.00 240 000 240 000 400 000
23⁄4 4 4.93 295 800 295 800 493 000
3 4 5.97 358 200 358 200 597 000
31⁄4 4 7.10 426 000 426 000 710 000
  
31⁄2 4 8.33 499 800 499 800 833 000
33⁄4 4 9.66 579 600 579 600 966 000
4 4 11.08 664 800 664 800 1 108 000

A Area calculated from the equation: As = 0.7854 [ D- (0.9743/n)]2

Where: As = stress area, D = nominal diameter of bolt, and n = threads per inch.

B1 lbf = 4.448 N.
C Based on 60 ksi (414 MPa).
D Based on 60–100 ksi (414–690 MPa).

Tensile Requirements for Machined Specimens

Grade A Grade B Grade C
Tensile strength, ksi 60 min 60–100 58–80
Yield point, min ksi . . . . . . 36
Elongation in 2 in., 18 18 23
min, %

Sample Sizes and Acceptance Numbers for Inspection of 
Hot-Dip or Mechanically Deposited Zinc-Coated Threads

Lot Size Sample Size A, B Acceptance Number A
2 to 90 13 1
91 to 150 20 2
151 to 280 32 3
281 to 500 50 5
501 to 1 200 80 7
1 201 to 3 200 125 10
3 201 to 10 000 200 14
10 001 and over 315 21
A Sample sizes of acceptance numbers are extracted from “Single Sampling Plan for Normal Inspection."
B Inspect all bolts in the lot if the lot size is less than the sample size.