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Socket Head Cap Screw

ASTM A574 socket head cap screws (also known as Allen head screws) have a cylindrical head with a flat chamfered top surface, knurled cylindrical sides and hexagonal recess. The ASTM A574 specification covers the complete requirement for quenched and tempered high strength alloy steel hexagon socket head cap screws. Dimensional specifications are governed by ASME B18.3. Socket Head Cap screws supply greater tensile strength than equivalent hex head cap screws, while requiring less surface area to counterbore.These fasteners are commonly used in applications in which it is necessary to recess the head of the fastener, as well as applications where space limits the size of the head, and the tool that drives the fastener. Thread lengths listed are minimum thread lengths, actual thread length may be longer.

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Governing Standards
Mechanical Properties
Chemical Properties
Dimensional Specifications

Dimensional Specifications

Dimensional SpecificationsAlloy Steel Socket Head Cap Screw

Per ASME B18.3-2012
Size	Nominal	UNC	UNF	D		A		H		J		LT
				Body Diameter		Head Diameter		Head Height		Hex Socket Size		Thread Length
				Max	Min	Max	Min	Max	Min	Fraction Nominal	Decimal Nominal	Min
#0	0.0600		80	0.0600	0.0568	0.0960	0.0910	0.0600	0.0570	….	0.0500	0.5000
#1	0.0730	64	72	0.0730	0.0695	0.1180	0.1120	0.0730	0.0700	1/16	0.0620	0.6625
#2	0.0860	56	64	0.0860	0.0822	0.1400	0.1340	0.0860	0.0830	5/64	0.0780	0.6250
#3	0.0990	48	56	0.0990	0.0949	0.1610	0.1540	0.0990	0.0950	5/64	0.0780	0.6250
#4	0.1120	40	48	0.1120	0.1075	0.1830	0.1760	0.1120	0.1080	3/32	0.0940	0.7500
#5	0.1250	40	44	0.1250	0.1202	0.2050	0.1980	0.1250	0.1210	3/32	0.0940	0.7500
#6	0.1380	32	40	0.1380	0.1329	0.2260	2.1800	0.1380	0.1340	7/64	0.1090	0.7500
#8	0.1640	32	36	0.1640	0.1585	0.2700	2.6200	0.1640	0.1590	9/64	0.1410	0.8750
#10	0.1900	24	32	0.1900	0.1840	0.3120	0.3030	0.1900	0.1850	5/32	0.1560	0.8750
#12	0.2120	24	28	0.2160	0.2095	0.3240	0.3140	0.2160	0.2100	5/32	0.1560	0.8750
1/4	0.2500	20	28	0.2500	0.2435	0.3750	0.3650	0.2500	0.2440	3/16	0.1880	1.0000
5/16	0.3125	18	24	0.3125	0.3053	0.4690	0.4570	0.3120	0.3060	1/4	0.2500	1.1250
3/8	0.3750	16	24	0.3750	0.3678	0.5620	0.5500	0.3750	0.3680	5/16	0.3120	1.2500
7/16	0.4375	14	20	0.4375	0.4294	0.6560	0.6420	0.4380	0.4300	3/8	0.3750	1.3750
1/2	0.5000	13	20	0.5000	0.4919	0.7500	0.7350	0.5000	0.4920	3/8	0.3750	1.5000
5/8	0.6250	11	18	0.6250	0.6163	0.9380	0.9210	0.6250	0.6160	1/2	0.5000	1.7500
3/4	0.7500	10	16	0.7500	0.7406	1.1250	1.1070	0.7500	0.7400	5/8	0.6250	2.0000
7/8	0.8750	9	14	0.8750	0.8647	1.3120	1.2930	0.8750	0.8640	3/4	0.7500	2.2500
1	1.0000	8	14	1.0000	0.9886	1.5000	1.4790	1.0000	0.9880	3/4	0.7500	2.5000
1 1/8	1.1250	7	12	1.1250	1.1086	1.6880	1.6650	1.1250	1.1110	7/8	0.8750	2.7500
1 1/4	1.2500	7	12	1.2500	1.2336	1.8750	1.8520	1.2500	1.2360	7/8	0.8750	3.0000
1 3/8	1.3750	7	12	1.3750	1.3568	2.0620	2.0380	1.3750	1.3600	1	1.0000	3.2500
1 1/2	1.5000	6	12	1.5000	1.4818	2.2500	2.2240	1.5000	1.4850	1	1.0000	3.5000
1 3/4	1.7500	5	12	1.7500	1.7295	2.6250	2.5970	1.7500	1.7340	1 1/4	1.2500	4.3800
2	2.0000	4	12	2.0000	1.9780	3.0000	2.9700	2.0000	1.9830	1 1/2	1.5000	5.0000
2 1/4	2.2500	4	12	2.2500	2.2280	3.3750	3.3440	2.2500	2.2320	1 3/4	1.7500	5.6200
2 1/2	2.5000	4	12	2.5000	2.4762	3.7500	3.7170	2.5000	2.4810	1 3/4	1.7500	6.2500
2 3/4	2.7500	4	12	2.7500	2.7262	4.1250	4.0900	2.7500	2.7300	2	2.0000	6.8800
3	3.0000	4	12	3.0000	2.9762	4.5000	4.4640	3.0000	3.9790	2 1/4	2.2500	7.5000
3 1/4	3.2500	4	12	3.2500	3.2262	4.8750	4.8300	3.2500	3.2280	2 1/4	2.2500	8.1200
3 1/2	3.5000	4	12	3.5000	3.4762	5.2500	5.2110	3.5000	3.4780	2 3/4	2.7500	8.7500
3 3/4	3.7500	4	12	3.7500	3.7262	5.6250	5.5840	3.7500	3.7270	2 3/4	2.7500	9.3800
4	4.0000	4	12	4.0000	3.9762	6.0000	5.9580	4.0000	3.9760	3	3.0000	10.0000

All dimensions are in inches.

Socket Head Cap Screw

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Diameter Thread Pitch Length Item # Availability Price Quantity UOM

1 1/2

SCAC 50150

In Stock

$0.47283/EA

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#5-40 X 1 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.47283/EA

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Quantity	Price
Quantity	Price
1	$0.47283/EA
1970	$0.44137/EA
7850	$0.39812/EA
35300	$0.24883/EA

1 1/2

SCAC 60150

In Stock

$0.35359/EA

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#6-32 X 1 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.35359/EA

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Quantity	Price
Quantity	Price
1	$0.35359/EA
1670	$0.33007/EA
6670	$0.29772/EA
30000	$0.18608/EA

1/4

1 3/4

SCAC0250175

In Stock

$0.23948/EA

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1/4-20 X 1 3/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.23948/EA

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In Stock

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Quantity	Price
Quantity	Price
1	$0.23948/EA
410	$0.22355/EA
1630	$0.20164/EA
7320	$0.12603/EA

1/4

1 3/4

SCAF0250175

In Stock

$0.24029/EA

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1/4-28 X 1 3/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.24029/EA

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In Stock

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Quantity	Price
Quantity	Price
1	$0.24029/EA
410	$0.22405/EA
1630	$0.21157/EA
7320	$0.14392/EA

3/8

SCAC0370200

In Stock

$0.50062/EA

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3/8-16 X 2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.50062/EA

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In Stock

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Quantity	Price
Quantity	Price
1	$0.50062/EA
150	$0.46732/EA
580	$0.42152/EA
2610	$0.26345/EA

3/8

SCAF0370200

In Stock

$0.69884/EA

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3/8-24 X 2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$0.69884/EA

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Quantity	Price
Quantity	Price
1	$0.69884/EA
150	$0.65161/EA
580	$0.6153/EA
2610	$0.41857/EA

1/2

2 1/4

SCAC0500225

In Stock

$1.24546/EA

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1/2-13 X 2 1/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$1.24546/EA

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In Stock

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Quantity	Price
Quantity	Price
1	$1.24546/EA
70	$1.16262/EA
270	$1.04868/EA
1190	$0.65543/EA

1/2

2 1/4

SCAF0500225

In Stock

$1.38326/EA

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1/2-20 X 2 1/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$1.38326/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$1.38326/EA
70	$1.28977/EA
270	$1.21791/EA
1190	$0.8285/EA

5/8

2 1/2

SCAC0620250

In Stock

$2.32233/EA

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5/8-11 X 2 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$2.32233/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$2.32233/EA
40	$2.16785/EA
150	$1.9554/EA
660	$1.22213/EA

5/8

2 1/2

SCAF0620250

In Stock

$2.98642/EA

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5/8-18 X 2 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

$2.98642/EA

Qty

In Stock

Product Detail

Quantity	Price
Quantity	Price
1	$2.98642/EA
40	$2.78458/EA
150	$2.62944/EA
660	$1.7887/EA

ASTM A574	Covers the requirements for quenched and tempered alloy steel hexagon socket-head cap screws, 0.060 through 4 in. in diameter where high strength is required.
ASME B18.3	Covers the complete general and dimensional data for various types of hexagon socket cap screws, shoulder screws, set screws, and hexagon keys recognized as an American National Standard.
ASME B1.1 UNC & UNF Class 2A	Specifies the thread form, series, class, allowance, tolerance, and designation for unified screw threads.

Alloy Steel, Quenched & Tempered			Per ASTM A574-13
Nominal Diameter	Full-Size Screws		Product Hardness	Machined Test Specimen
	Tensile Strength	Proof Load	Product Hardness	Yield Strength at 0.2% offset	Tensile Strength	Elongation in 5D	Reduction of Area
	ksi	ksi	Rockwell	ksi	ksi	%	%
1/2" & under	180 min	140	39-45 HRC	153 min	180 min	10 min	35 min
over 1/2"	170 min	135	37-45 HRC	153 min	170 min	10 min	35 min

Per ASTM A574-13
Material	Heat Analysis				Product Analysis
	Carbon	Phosphorus	Sulfur	Alloying Elements	Carbon	Phosphorus	Sulfur	Alloying Elements
	% by weight	% by weight	% by weight	Alloying Elements	% by weight	% by weight	% by weight	Alloying Elements
Quenched and tempered alloy steel	0.33 min	0.035 max	0.040 max	(1)	0.31 min	0.040 max	0.045 max	(1)

Socket Head Cap Screw

Technical Data

Governing Standards

Governing StandardsAlloy Steel Socket Head Cap Screw

Mechanical Properties

Mechanical PropertiesAlloy Steel Socket Head Cap Screw

Chemical Properties

Chemical PropertiesAlloy Steel Socket Head Cap Screw

Dimensional Specifications

Dimensional SpecificationsAlloy Steel Socket Head Cap Screw

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Body Diameter

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Length

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Thread Length

Thread Type

Diameter

Width Across Flats

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#5-40 X 1 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

#6-32 X 1 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

1/4-20 X 1 3/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

1/4-28 X 1 3/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

3/8-16 X 2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

3/8-24 X 2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

1/2-13 X 2 1/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

1/2-20 X 2 1/4 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

5/8-11 X 2 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW

5/8-18 X 2 1/2 A574 ALLOY STEEL SOCKET HEAD CAP SCREW