ASTM A668

Summary

ASTM A668 covers untreated and heat treated carbon and alloy steel forgings for general industrial use. A668 cover carbon forgings in six classes, and alloy steel forgings in seven classes. Other forging specifications are available for specific applications. A common item Portland Bolt supplies that is made to ASTM A668 are Clevises as used in tie rod assemblies. The standard class is class A, although other classes can be quoted upon request. Available strength in kips per AISC available on our website.

A668 Chemical Requirements

Element Classes A to F and AH to FH Classes G to N and GH to NH
Manganese % max 1.35 -
Phosphorous % max 0.050 0.040
Sulfur % max 0.050 0.040

A668 Mechanical Requirements

Class Size, inches Tensile, min ksi Yield, min ksi Elong, % min in 2” RA, % min Hardness, HBN
A Up to 20 47 - - - 183 max
B Up to 20 60 30 24 36 120-174
C Up to 12 66 33 23 36 137-183
12 to 20 66 33 22 34 137-183
D Up to 8 75 37.5 24 40 149-207
8 to 12 75 37.5 22 35 149-207
12 to 20 75 37.5 20 19 149-207
Over 20 75 37.5 19 30 149-207
E Up to 8 85 44 25 40 174-217
8 to 12 85 44 23 37 174-217
12 to 20 83 43 22 35 174-217
F Up to 4 90 55 20 39 187-235
4 to 7 85 50 20 39 174-217
7 to 10 85 50 19 37 174-217
10 to 20 82 48 19 36 174-217
G Up to 12 80 50 24 40 163-207
12 to 20 80 50 22 38 163-207
H Up to 7 90 60 22 44 187-235
7 to 10 90 58 21 42 187-235
10 to 20 90 58 18 40 187-235
J Up to 7 95 70 20 50 197-255
7 to 10 90 65 20 50 187-235
10 to 20 90 65 18 48 207-255
K Up to 7 105 80 20 50 212-269
7 to 10 100 75 19 50 207-269
10 to 20 100 75 18 48 207-269
L Up to 4 125 105 16 50 255-321
4 to 7 115 95 16 45 235-302
7 to 10 110 85 16 45 223-293
10 to 20 110 85 14 40 223-293
M Up to 4 145 120 15 45 293-352
4 to 7 140 115 14 40 285-341
7 to 10 135 110 13 40 269-331
10 to 20 135 110 12 38 269-341
N Up to 4 170 140 13 40 331-401
4 to 7 165 135 12 35 331-401
7 to 10 160 130 11 35 321-388
10 to 20 160 130 11 35 321-402
Classes with an added ‘H’ are supplied on the basis of hardness values only. For example, AH. Classes A-F are carbon steel, classes G-N are alloy steel

A668 Heat Treatment

Class Heat Treatment
A Untreated
B Annealed, or normalized, or normalized and tempered
C Annealed, or normalized, or normalized and tempered
D Annealed, or normalized, or normalized and tempered
E Normalized and tempered or double normalized and tempered
F Quenched and tempered, or normalized, quenched and tempered
G Annealed, or normalized, or normalized and tempered
H Normalized and tempered
J Normalized and tempered, or normalized, quenched and tempered
K Normalized, quenched and tempered
L Normalized, quenched and tempered
M Normalized, quenched and tempered
N Normalized, quenched and tempered
Classes with an added ‘H’ are supplied on the basis of hardness values only. For example, AH.