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ASTM A574/A574M Alloy Steel Socket Head Cap Screws Specification

Quenched & tempered Alloy Steel Hexagon Socket Head Cap Screws

ASTM A574/A574M Socket Head Cap Screws, 12 Point Screws

ASTM A574/A574M covers quenched and tempered alloy steel Socket Head Cap Screws and Allen Bolts ranging form size #0 to 4 inch. The screws shall be fabricated from alloy steel made to a fine grain practice. In the event of controversy over grain size, referee tests on finished screws conducted in accordance with Test Methods E112 shall prevail. Screws in sizes through 0.625 in. diameter, and for product lengths through 4 in. shall be roll threaded, unless otherwise specified by the purchaser. Larger products shall be rolled, cut, or ground at the option of the manufacturer. Screws shall be heat treated by quenching in oil from above the transformation temperature and then tempered by reheating to at least 700°F to achieve the desired mechanical properties.

ASTM A574/A574M Chemical Composition

Element Composition, %
Heat Analysis Product Analysis
C, min 0.33 0.31
P, max 0.035 0.040
S, max 0.040 0.045

ASTM A574/A574M Chemical Composition S1

Elements Grade Designation ASTM A574/A574M 4137 ASTM A574/A574M 4142 ASTM A574/A574M 4145 ASTM A574/A574M 4340 ASTM A574/A574M 8740 ASTM A574/A574M 5137M ASTM A574/A574M 51B37M
UNS Number G41370 G41420 G41450 G43400 G87400 . . . . . .
C Heat Analysis 0.35-0.40 0.40-0.45 0.43-0.48 0.38-0.43 0.38-0.43 0.35-0.40 0.33-0.40
Product Analysis 0.33-0.42 0.38-0.47 0.41-0.50 0.36-0.45 0.36-0.45 0.33-0.42 0.31-0.42
Mn Heat Analysis 0.70-0.90 0.75-1.00 0.75-1.00 0.60-0.80 0.75-1.00 0.30-0.50 0.30-0.50
Product Analysis 0.67-0.93 0.71-1.04 0.71-1.04 0.57-0.83 0.71-1.04 0.27-0.53 0.27-0.53
P, max Heat Analysis 0.035 0.035 0.035 0.035 0.035 0.035 0.035
Product Analysis 0.04 0.04 0.04 0.04 0.04 0.04 0.04
S max Heat Analysis 0.04 0.04 0.04 0.04 0.04 0.04 0.04
Product Analysis 0.045 0.045 0.045 0.045 0.045 0.045 0.045
Si Heat Analysis 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35 0.15-0.35
Product Analysis 0.13-0.37 0.13-0.37 0.13-0.37 0.13-0.37 0.13-0.37 0.13-0.37 0.13-0.37
Ni Heat Analysis A A A 1.65-2.00 0.40-0.70 A A
Product Analysis . . . . . . . . . 1.65-2.05 0.37-0.73 . . . . . .
Cr Heat Analysis 0.80-1.10 0.80-1.10 0.80-1.10 0.70-0.90 0.40-0.60 0.90-1.20 0.95-1.25
Product Analysis 0.75-1.15 0.75-1.15 0.75-1.15 0.67-0.93 0.37-0.63 0.85-1.25 0.90-1.30
Mo Heat Analysis 0.15-0.25 0.15-0.25 0.15-0.25 0.20-0.30 0.20-0.30 A A
Product Analysis 0.13-0.27 0.13-0.27 0.13-0.27 0.18-0.32 0.18-0.32 . . . . . .
B Heat Analysis A A A A A A 0.0005-0.003
Product Analysis . . . . . . . . . . . . . . . . . . B
  • (A) Elements shown with an "A" are not applicable to that grade designation.
  • (B) Boron is not subject to product analysis.

ASTM A574/A574M Mechanical Requirements

Property ≤0.5 in. Nom. Dia. >0.5 in. and < 1.0 in. Nom. Dia. ≥1.0 in. Nom. Dia.
Full-size screws:
Tensile or wedge tensile strength, min, ksi 180 170 170
Proof load (stress), ksi 140 135 135
Product hardness:
Rockwell (HRC) 39-44 37-44 37-44
Machined test specimen:
Yield strength at 0.2% offset, min., ksi A A 153
Tensile strength, min., ksi A A 170
Elongation in 4D, min. A A 10%
Reduction of area, min. A A 35%
  • (A) Not Applicable.

ASTM A574/A574M Mechanical Testing Requirements

Item Nom.
Dia.		 Tensile Load,
 min, lb		 Product Length Hardness,
max		 Hardness,
min		 Decarb/Carburization Test Conducted
Using Full Size
Product		 Test Conducted
Using Machined
Test Specimen
Proof
Load		 Wedge
Tensile
Strength		 Axial
Tensile
Strength		 Yield
Strength
at 0.2% Offset		 Tensile
Strength		 Elongation % Red. 
of Area
1 All short
lengths		 … Less than 3D A B B B ... ... ... ... ... ... ...
2 <1.0 in. … Over 3DA B ... B ZC B ... ... ... ... ...
3 ≥1.0 in. ≤270,000 Over 3DA B ... B ZC XD ... YD YD YD YD
4 ≥1.0 in. >270,000 Over 3DA B ... B ZC ... XD YD YD YD YD
  • (A) D denotes nominal diameter of product.
  • (B) Denotes mandatory test.
  • (C) Proof load test denoted Z shall be conducted when purchaser requests the test in inquiry and order.
  • (D) Either all tests denoted by X or all tests denoted by Y shall be performed. In case of arbitration full-size tests, denoted X, shall be decisive.

ASTM A574/A574M Tensile Requirements for Coarse Thread Screws

Screw Dia (D), in. Threads/ in. Tensile Load, min, lbf A Stress Area, in.2 B Proof Load (Length Measurement Method), min, lbf C
0.073 64 473 0. 00263 368
0.086 56 666 0. 00370 518
0.099 48 877 0. 00487 682
0.112 40 1 090 0. 00604 846
0.125 40 1 430 0. 00796 1 110
0.138 32 1 640 0. 00909 1 270
0.164 32 2 520 0. 0140 1 960
0.190 24 3 150 0. 0175 2 450
0.216 24 4 350 0. 0242 3 380
0.250 20 5 730 0. 0318 4 450
0.3125 18 9 440 0. 0524 7 340
0.375 16 13 900 0. 0775 10 800
0.4375 14 19 100 0. 1063 14 900
0.500 13 25 500 0. 1419 19 900
0.5625 12 30 900 0. 182 24 600
0.625 11 38 400 0. 226 30 500
0.750 10 56 800 0. 334 45 100
0.875 9 78 500 0. 462 62 400
1.000 8 103 000 0. 606 81 800
1.125 7 129 000 0. 763 103 000
1.250 7 165 000 0. 969 131 000
1.375 6 196 000 1. 155 156 000
1.500 6 239 000 1. 405 190 000
1.750 5 323 000 1. 90 256 000
2.000 41/2 425 000 2. 50 338 000
2.250 41/2 552 000 3. 25 439 000
2.500 4 680 000 4. 00 540 000
2.750 4 838 000 4. 93 666 000
3.000 4 1 010 000 5. 97 806 000
3.250 4 1 210 000 7. 10 958 000
3.500 4 1 420 000 8. 33 1 120 000
3.750 4 1 640 000 9. 66 1 300 000
4.000 4 1 880 000 11. 08 1 500 000
  • (A) Values based on 180 ksi for 0.500 and smaller and 170 ksi for sizes larger than 0.500 in. and stress area in accordance with Footnote B.
  • (B) Stress areas based on Handbook H-28 (U.S. Department of Commerce) as follows: 
  • (C) Values based on 140 ksi for 0.500 and smaller and 135 ksi for sizes larger than 0.500 in. and stress area in accordance with Footnote B.

ASTM A574/A574M Tensile Requirements for Fine Thread Screws

Screw Dia (D), in. Threads/ in. Tensile Load, min, lbf A Stress Area, in.2 B Proof Load (Length Measurement Method) min, lbf C
0.060 80 324 0.00180 252
0.073 72 500 0.00278 389
0.086 64 709 0.00394 552
0.099 56 941 0.00523 732
0.112 48 1 190 0.00661 925
0.125 44 1 490 0.00830 1 160
0.138 40 1 830 0.01015 1 420
0.164 36 2 650 0.01474 2 060
0.190 32 3 600 0.0200 2 800
0.250 28 6 500 0.0364 5 100
0.216 28 4 600 0.0258 3 600
0.3125 24 10 400 0.0580 8 120
0.375 24 15 800 0.0878 12 300
0.4375 20 21 400 0.1187 16 600
0.500 20 28 800 0.1599 22 400
0.5625 18 34 500 0.203 27 400
0.625 18 43 500 0.256 34 600
0.750 16 63 400 0.373 50 400
0.875 14 86 500 0.509 68 700
1.000 12 113 000 0.663 89 500
1.125 12 146 000 0.856 116 000
1.250 12 182 000 1.073 145 000
1.375 12 224 000 1.315 178 000
1.500 12 269 000 1.581 213 000
  • (A) Values based on 180 ksi for 0.500 and smaller and 170 ksi for sizes larger than 0.500 in. and stress area in accordance with Footnote B.
  • (B) Stress areas based on H-28 as follows: 
  • (C) Values based on 140 ksi for 0.500 and smaller and 135 ksi for sizes larger than 0.500 in. and stress area in accordance with Footnote B.

ASTM A574/A574M Wedge Test Angles

Screw Size, D, in. Wedge Angle, Deg
Body Lengths 2D or Less or Threaded to the Head Body Lengths Greater than 2D
0.112 - 0.500, incl 6 10
0.625 - 0.750, incl 6 8
0.875 to 1.500, incl 4 6

ASTM A574/A574M Bolting Surface Treatment Specifications

ASTM A574/A574M Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.

ASME Dimensional Standards

IFI 115 12 Point Flange Screws B18.3 Imperial Hexagon Socket and Spline Socket Screws

ASTM A574/A574M Bolting Certifications

  • EN 10204 3.1
  • EN 10204 3.2
  • PED 2014/68/EC
  • MERKBLATT AD 2000 W2/W7/W10
  • API 20 E BSL 1/ BSL 2
  • NACE MR 0175
  • NACE MR 0103

ASTM A574/A574M Testing Standards

A751 Test Methods, Practices, and Terminology for Chemical Analysis of Steel Products
E112 Test Methods for Determining Average Grain Size
F606/F606M Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, Direct Tension Indicators, and Rivets
F788 Specification for Surface Discontinuities of Bolts, Screws, and Studs, Inch and Metric Series

ASME Threading Specifications

ASME B1.1 Unified Inch Screw Threads (UN and UNR Thread Form)
ASME B1.3 Screw Thread Gaging System for Dimensional Acceptability - Inch Screw Threads (IN, UNR, and UNJ)
ASME B1.13M Metric Screw Threads - M Profile
ASME B1.21M Metric Screw Threads - MJ Profile

ASTM A574/A574M Supplementary Requirements

S1 Specific Grade Chemical Compositions