B7 Heavy Hex Bolt
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B7 Heavy Hex Bolt

ASTM A193 Grade B7 heavy hex head bolts are high strength fasteners manufactured from heat treated alloy steel AISI 4140/4142, quenched and tempered. Dimensional specifications are governed by ASME B18.2.1. Grade markings consists of both the grade symbol "B7" and the manufacturer's identification mark. Inch series fasteners meeting ASTM A193 Grade B7 specifications are typically used in flange bolting applications. ASTM A193 covers the requirements for high temperature and high pressure bolting. Heavy hex head bolts have a larger head to increase the bearing surface and distribute the clamping load over a larger area. Bolts listed that are smaller than 1/2" diameter may be finished pattern bolts. A193 B7 hex bolts, as well as all thread stud bolts having diameters above 1" are most common 8UN (8 threads per inch) and are also available UNC (coarse thread).

Governing StandardsGrade B7

ASTM A193 Covers the mechanical and material requirements for inch series fasteners used in automotive and related industries in diameters through 1-1/2″.
ASME B18.2.1 Covers the complete general and dimensional data for multiple types of inch series square and hex bolts and screws.
ASME B1.1 UNC & UNF Class 2A Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

Grade B7 Head Marking
Grade B7 Material Marking

Mechanical PropertiesGrade B7

Chromium-Molybdenum, Quenched & Tempered Per ASTM A193/A193M-16
Diameter Tempering
Temperature
Tensile
Strength
Yield Strength min,
0.2% offset
Elongation
in 4D
Reduction
in Area
Hardness
Min Min ksi ksi Min % Min % Max
up to 2 1/2" 1100F 125 105 16 50 321 HBW or 35 HRC
over 2 1/2" to 4" 1100F 115 95 16 50 321 HBW or 35 HRC
over 4 to 7" 1100F 100 75 18 50 321 HBW or 35 HRC

Chemical PropertiesGrade B7

Per ASTM A193/A193M-16
Grade Material Carbon Manganese Phosphorus Sulfur Silicon Chromium Molybdenum
% by   weight % by weight % by weight % by weight % by weight % by weight % by weight
B7 Chromium-Molybdenum (1) 0.38-0.48 (2) 0.75-1.00 0.035 max 0.04 max 0.15-0.35 0.80-1.10 0.15-0.25
  1. 1. Typical steel compositions used for this grade include 4140, 4142, 4145, 4140H, 4142H, and 4145H.
  2. 2. For bar sizes over 3 1/2 in. [90 mm], inclusive, the carbon content may be 0.50 % max. For the B7M grade, a minimum carbon of 0.28 % is permitted, provided that the required tensile properties are met in the section sizes involved, the use of AISI 4130 or 4130H is allowed.

Dimensional SpecificationsGrade B7

Heavy Hex Bolt dimensions
Per ASME B18.2.1-2012
Nominal
Diameter
UNC UNF E F G H J LT Y
Body Diameter Width Across Flats Width Across
Corners
Head Height Wrench
Height
Thread Length Transition
Length
Max Min Basic Max Min Max Min Basic Max Min Min Lengths
up to 6"
Lengths
> 6"
Max
1/4 0.2500 20 28 0.2500 0.2405 7/16 0.4380 0.4280 0.5050 0.4880 5/32 0.1630 0.1500 0.1060 0.7500 1.0000 0.2500
5/16 0.3125 18 24 0.3125 0.3065 1/2 0.5000 0.4890 0.5770 0.5570 13/64 0.2110 0.1950 0.1400 0.8750 1.1250 0.2750
3/8 0.3750 16 24 0.3750 0.3690 9/16 0.5620 0.5510 0.6500 0.6280 15/64 0.2430 0.2260 0.1600 1.0000 1.2500 0.3120
7/16 0.4375 14 20 0.4375 0.4305 5/8 0.6250 0.6120 0.7220 0.6980 9/32 0.2910 0.2720 0.1950 1.1250 1.3750 0.3570
1/2 0.5000 13 20 0.5000 0.4930 3/4 0.7500 0.7360 0.8660 0.8400 5/16 0.3230 0.3020 0.2150 1.2500 1.5000 0.3850
9/16 0.5625 12 18 0.5625 0.5545 13/16 0.8120 0.7980 0.9380 0.9100 23/64 0.3710 0.3480 0.2500 1.3750 1.6250 0.4170
5/8 0.6250 11 18 0.6250 0.6170 15/16 0.9380 0.9220 1.0830 1.0510 25/64 0.4030 0.3780 0.2690 1.5000 1.7500 0.4550
3/4 0.7500 10 16 0.7500 0.7410 1 1/8 1.1250 1.1000 1.2990 1.2540 15/32 0.4830 0.4550 0.3240 1.7500 2.0000 0.5000
7/8 0.8750 9 14 0.8750 0.8660 1 5/16 1.3120 1.2850 1.5160 1.4650 35/64 0.5630 0.5310 0.3780 2.0000 2.2500 0.5560
1 1.0000 8 14 1.0000 0.9900 1 1/2 1.5000 1.4690 1.7320 1.6750 39/64 0.6270 0.5910 0.4160 2.2500 2.5000 0.6250
1 1/8 1.1250 7 12 1.1250 1.1140 1 11/16 1.6880 1.6310 1.9490 1.8590 11/16 0.7180 0.6580 0.4610 2.5000 2.7500 0.7140
1 1/4 1.2500 7 12 1.2500 1.2390 1 7/8 1.8750 1.8120 2.1650 2.0660 25/32 0.8130 0.7490 0.5300 2.7500 3.0000 0.7140
1 3/8 1.3750 6 12 1.3750 1.3630 2 1/16 2.0620 1.9940 2.3820 2.2730 27/32 0.8780 0.8100 0.5690 3.0000 3.2500 0.8330
1 1/2 1.5000 6 12 1.5000 1.4880 2 1/4 2.2500 2.1750 2.5980 2.4800 15/16 0.9740 0.9020 0.6400 3.2500 3.5000 0.8330
  1. All dimensions are in inches.
  2. Usable thread length for Hex Head Cap Screws under 6 1/4" long can be approximated by the equation THREAD LENGTH = (2 X DIAMETER) + 1/4″
B7 Heavy Hex Bolt
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Diameter Thread Pitch Length Threading Item # Availability Price Quantity UOM
1/4 20 3/4 Full HHB70250075-I In Stock $0.48749/EA EA
1/4 20 1 Full HHB70250100-I In Stock $0.55249/EA EA
1/4 20 1 1/4 Partial HHB70250125-I In Stock $0.64998/EA EA
1/4 20 1 1/2 Partial HHB70250150-I In Stock $0.74748/EA EA
1/4 20 2 Partial HHB70250200-I In Stock $0.84498/EA EA
5/16 18 1 Full HHB70310100-I In Stock $0.69548/EA EA
5/16 18 1 1/4 Full HHB70310125-I In Stock $0.87748/EA EA
3/8 16 1 Full HHB70370100-I In Stock $0.58794/EA EA
3/8 16 1 1/4 Full HHB70370125-I In Stock $0.58164/EA EA
3/8 16 1 1/2 Partial HHB70370150-I In Stock $0.62912/EA EA
3/8 16 1 3/4 Partial HHB70370175-I In Stock $0.90907/EA EA
3/8 16 2 Partial HHB70370200-I In Stock $0.93997/EA EA
1/2 13 1 Full HHB70500100-I In Stock $0.7014/EA EA
1/2 13 1 1/4 Full HHB70500125-I In Stock $0.4338/EA EA
1/2 13 1 1/2 Full HHB70500150-I In Stock $0.59669/EA EA
1/2 13 1 3/4 Full HHB70500175-I In Stock $0.95193/EA EA
1/2 13 2 Partial HHB70500200-I In Stock $0.75301/EA EA
1/2 13 2 1/4 Partial HHB70500225-I In Stock $1.05853/EA EA
1/2 13 2 1/2 Partial HHB70500250-I In Stock $1.14495/EA EA
1/2 13 2 3/4 Partial HHB70500275-I In Stock $0.65148/EA EA
1/2 13 3 Partial HHB70500300-I In Stock $1.28265/EA EA
1/2 13 3 1/4 Partial HHB70500325-I In Stock $1.0573/EA EA
1/2 13 3 1/2 Partial HHB70500350-I In Stock $1.26968/EA EA
1/2 13 3 3/4 Partial HHB70500375-I 3-5 Working Days $1.62496/EA EA
1/2 13 4 Partial HHB70500400-I In Stock $1.12541/EA EA
1/2 13 4 1/2 Partial HHB70500450-I In Stock $2.30809/EA EA
1/2 13 5 Partial HHB70500500-I 3-5 Working Days $1.73565/EA EA
5/8 11 1 Full HHB70620100-I In Stock $0.9105/EA EA
5/8 11 1 1/4 Full HHB70620125-I In Stock $1.07936/EA EA
5/8 11 1 1/2 Full HHB70620150-I In Stock $1.05327/EA EA
5/8 11 1 3/4 Full HHB70620175-I In Stock $2.07004/EA EA
5/8 11 2 Full HHB70620200-I In Stock $1.33282/EA EA
5/8 11 2 1/4 Partial HHB70620225-I In Stock $1.13152/EA EA
5/8 11 2 1/2 Partial HHB70620250-I In Stock $1.32821/EA EA
5/8 11 2 3/4 Partial HHB70620275-I In Stock $1.6768/EA EA
5/8 11 3 Partial HHB70620300-I In Stock $1.69808/EA EA
5/8 11 3 1/4 Partial HHB70620325-I In Stock $1.19649/EA EA
5/8 11 3 1/2 Partial HHB70620350-I In Stock $1.2739/EA EA
5/8 11 3 3/4 Partial HHB70620375-I In Stock $1.86328/EA EA
5/8 11 4 Partial HHB70620400-I In Stock $1.67072/EA EA
5/8 11 4 1/2 Partial HHB70620450-I In Stock $3.30998/EA EA
5/8 11 5 Partial HHB70620500-I In Stock $2.31076/EA EA
5/8 11 5 1/2 Partial HHB70620550-I In Stock $3.44446/EA EA
5/8 11 6 Partial HHB70620600-I In Stock $3.41839/EA EA
3/4 10 1 1/2 Full HHB70750150-I In Stock $1.71433/EA EA
3/4 10 1 3/4 Full HHB70750175-I In Stock $2.03321/EA EA
3/4 10 2 Full HHB70750200-I In Stock $2.59376/EA EA
3/4 10 2 1/4 Full HHB70750225-I In Stock $2.09136/EA EA
3/4 10 2 1/2 Full HHB70750250-I In Stock $2.15629/EA EA
3/4 10 2 3/4 Partial HHB70750275-I In Stock $2.76604/EA EA
3/4 10 3 Partial HHB70750300-I In Stock $2.89288/EA EA
3/4 10 3 1/4 Partial HHB70750325-I In Stock $2.64677/EA EA
3/4 10 3 1/2 Partial HHB70750350-I In Stock $2.88521/EA EA
3/4 10 3 3/4 Partial HHB70750375-I In Stock $3.08768/EA EA
3/4 10 4 Partial HHB70750400-I In Stock $3.30201/EA EA
3/4 10 4 1/2 Partial HHB70750450-I In Stock $3.53006/EA EA
3/4 10 5 Partial HHB70750500-I 3-5 Working Days $4.35853/EA EA
3/4 10 5 1/2 Partial HHB70750550-I In Stock $4.1443/EA EA
3/4 10 6 Partial HHB70750600-I In Stock $4.42476/EA EA
7/8 9 2 Full HHB70870200-I In Stock $3.02593/EA EA
7/8 9 2 1/4 Full HHB70870225-I In Stock $3.02499/EA EA
7/8 9 2 1/2 Full HHB70870250-I In Stock $3.05242/EA EA
7/8 9 2 3/4 Full HHB70870275-I In Stock $4.22083/EA EA
7/8 9 3 Partial HHB70870300-I In Stock $3.67959/EA EA
7/8 9 3 1/2 Partial HHB70870350-I In Stock $4.22665/EA EA
7/8 9 3 3/4 Partial HHB70870375-I In Stock $3.62642/EA EA
7/8 9 4 Partial HHB70870400-I In Stock $4.13299/EA EA
7/8 9 4 1/4 Partial HHB70870425-I In Stock $6.46909/EA EA
7/8 9 4 1/2 Partial HHB70870450-I In Stock $5.01872/EA EA
7/8 9 4 3/4 Partial HHB70870475-I In Stock $5.22057/EA EA
7/8 9 5 Partial HHB70870500-I In Stock $7.45733/EA EA
7/8 9 5 1/2 Partial HHB70870550-I In Stock $6.83695/EA EA
7/8 9 6 Partial HHB70870600-I 3-5 Working Days $18.23204/EA EA
1 8 2 Full HHB71000200-I In Stock $2.75902/EA EA
1 8 2 1/4 Full HHB71000225-I In Stock $4.50913/EA EA
1 8 2 1/2 Full HHB71000250-I In Stock $4.55245/EA EA
1 8 2 3/4 Full HHB71000275-I In Stock $5.03065/EA EA
1 8 3 Full HHB71000300-I In Stock $5.70549/EA EA
1 8 3 1/4 Partial HHB71000325-I In Stock $8.78843/EA EA
1 8 3 1/2 Partial HHB71000350-I In Stock $3.50991/EA EA
1 8 3 3/4 Partial HHB71000375-I In Stock $4.0624/EA EA
1 8 4 Partial HHB71000400-I In Stock $8.69805/EA EA
1 8 4 1/4 Partial HHB71000425-I In Stock $5.54121/EA EA
1 8 4 1/2 Partial HHB71000450-I In Stock $6.1846/EA EA
1 8 5 Partial HHB71000500-I In Stock $7.74816/EA EA
1 8 5 1/2 Partial HHB71000550-I In Stock $8.53195/EA EA
1 8 6 Partial HHB71000600-I In Stock $10.92333/EA EA
1 1/8 7 3 Full HHB71120300C-I In Stock $12.24667/EA EA
1 1/8 7 3 1/2 Full HHB71120350C-I 3-5 Working Days $30.89763/EA EA
1 1/8 7 4 Partial HHB71120400C-I In Stock $24.29925/EA EA
1 1/8 7 5 Partial HHB71120500C-I In Stock $13.58752/EA EA
1 1/8 7 5 1/2 Partial HHB71120550C-I In Stock $29.32132/EA EA
1 1/8 7 6 Partial HHB71120600C-I 3-5 Working Days $12.83328/EA EA
1 1/8 8 3 Full HHB71120300-I In Stock $7.28164/EA EA
1 1/8 8 3 1/2 Full HHB71120350-I In Stock $8.56708/EA EA
1 1/8 8 4 Partial HHB71120400-I In Stock $10.14722/EA EA
1 1/8 8 4 1/2 Partial HHB71120450-I In Stock $10.51989/EA EA
1 1/8 8 5 Partial HHB71120500-I In Stock $11.23071/EA EA
1 1/8 8 5 1/2 Partial HHB71120550-I In Stock $22.11843/EA EA
1 1/8 8 6 Partial HHB71120600-I In Stock $10.56766/EA EA
1 1/4 7 3 Full HHB71250300C-I In Stock $11.73754/EA EA
1 1/4 7 3 1/2 Full HHB71250350C-I In Stock $11.46396/EA EA
1 1/4 7 4 1/2 Partial HHB71250450C-I In Stock $17.0675/EA EA
1 1/4 7 5 Partial HHB71250500C-I In Stock $16.17186/EA EA
1 1/4 7 6 Partial HHB71250600C-I In Stock $21.08385/EA EA
1 1/4 8 3 Full HHB71250300-I In Stock $10.83916/EA EA
1 1/4 8 3 1/2 Full HHB71250350-I In Stock $14.55678/EA EA
1 1/4 8 4 Partial HHB71250400-I In Stock $13.69815/EA EA
1 1/4 8 4 1/2 Partial HHB71250450-I In Stock $15.01787/EA EA
1 1/4 8 5 Partial HHB71250500-I In Stock $14.71651/EA EA
1 1/4 8 5 1/2 Partial HHB71250550-I In Stock $31.47098/EA EA
1 1/4 8 6 Partial HHB71250600-I In Stock $13.94556/EA EA
1 1/2 8 3 1/2 Full HHB71500350-I 3-5 Working Days $17.68547/EA EA
1 1/2 8 4 Full HHB71500400-I In Stock $133.67998/EA EA
1 1/2 8 4 1/2 Full HHB71500450-I 3-5 Working Days $57.71313/EA EA
1 1/2 8 5 Partial HHB71500500-I 3-5 Working Days $34.12415/EA EA
1 1/2 8 5 1/2 Partial HHB71500550-I 3-5 Working Days $49.34257/EA EA
1 1/2 8 6 Partial HHB71500600-I 3-5 Working Days $39.44514/EA EA