18-8 SS Flat Socket Cap Screw
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18-8 SS Flat Socket Cap Screw

ASTM F879 stainless flat socket head cap screws have a countersunk head with a flat top surface and hexagonal recess. The ASTM F879 specification covers the requirements for stainless steel hexagon flat countersunk head cap screws for use in applications requiring general corrosion resistance. Dimensional specifications are governed by ASME B18.3. Stainless flat socket head cap screws are commonly used in applications in which it is necessary to recess the head of the fastener flush with the surface. Stainless steel fasteners are commonly used in applications that require general atmospheric corrosion resistance, such as chemical and food processing equipment. Stainless steel has a higher corrosion resistance than carbon steel.

Governing StandardsStainless Steel Flat Socket Cap Screw

ASTM F879 This specification covers the chemical and mechanical requirements for stainless steel inch hexagon socket button (SBHCS) and flat countersunk (SFHCS) head cap screws with nominal thread 0.060 through 0.625 in. intended for use in applications requiring general corrosion resistance.
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.

Stainless Steel Flat Socket Cap Screw Head Marking
Stainless Steel Flat Socket Cap Screw requires no material marking

Mechanical PropertiesStainless Steel Flat Socket Cap Screw

Austenitic Stainless Steel Per ASTM F879-15
Alloy
Condition CW
Full-Size Product Tests (1) Machined Specimen Tests Core Hardness (2)
Tensile
Strength
Extension (3) Tensile
Strength
Yield
Strength
Elongation Vickers Rockwell
ksi Min ksi ksi % Min
80 min 0.4D 80 min 40 min 25 150 min 50 HRA min
  1. 1. Actual full-size testing of condition CW and CW1 may result in decreased tensile strength because of the head configuration (see Table 3). For fasteners with nominal thread diameters larger than 0.625 in., the mechanical properties shall be agreed upon between the user and manufacturer.
  2. 2. Core hardness is only required when full-size product testing cannot be accomplished.
  3. 3. D denotes nominal thread size.

Chemical PropertiesStainless Steel Flat Socket Cap Screw

Per ASTM F879-15
Material Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper
% by weight % by weight % by weight % by weight % by weight % by weight % by weight % by weight
Alloy Group 1,
UNS S30400
0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00
  1. Composition, % maximum except as shown.

Dimensional SpecificationsStainless Steel Flat Socket Cap Screw

 
Per ASME B18.3-2012
Size Nominal UNC UNF D A G P H J T L
Body Head Diameter Protrusion
Gage Diameter
Protrusion Head
Height
Hex Socket Size Key
Engagement
Thread Length
Max Min Max Min Max Min Max Min   Fraction Decimal Min Min Max
#0 0.0600   80 0.0600 0.0568 0.1380 0.1170 0.0780 0.0770 0.0360 0.0260 0.0440 …. 0.0350 0.0250 0.5000 0.6200
#1 0.0730 64 72 0.0730 0.0695 0.1680 0.1430 0.1010 0.1000 0.0400 0.0280 0.0540 …. 0.0500 0.0310 0.6200 0.7700
#2 0.0860 56 64 0.0860 0.0822 0.1970 0.1630 0.1240 0.1230 0.0430 0.0310 0.0640 …. 0.0500 0.0380 0.6200 0.8000
#3 0.0990 48 56 0.0990 0.0949 0.2260 0.1930 0.1480 0.1470 0.0460 0.0330 0.0730 1/16 0.0620 0.0440 0.6200 0.8300
#4 0.1120 40 48 0.1120 0.1075 0.2550 0.2180 0.1720 0.1710 0.0490 0.0360 0.0890 1/16 0.0620 0.0550 0.7500 0.9900
#5 0.1250 40 44 0.1250 0.1202 0.2810 0.2400 0.1960 0.1950 0.0510 0.0370 0.0900 5/64 0.0780 0.0610 0.7500 1.0000
#6 0.1380 32 40 0.1380 0.1329 0.3070 0.2630 0.2200 0.2190 0.0520 0.0370 0.0970 5/64 0.0780 0.0660 0.7500 1.0500
#8 0.1640 32 36 0.1640 0.1585 0.3590 0.3110 0.2670 0.2660 0.0550 0.0390 0.1120 3/32 0.0940 0.0760 0.8750 1.1900
#10 0.1900 24 32 0.1900 0.1840 0.4110 0.3590 0.3130 0.3120 0.0580 0.0410 0.1270 1/8 0.1250 0.0870 0.8750 1.2700
#12 0.2120 24 28 0.2160 0.2095 0.4500 0.4100 0.3600 0.3590 0.0690 0.0420 0.1350 1/8 0.1250 0.0940 1.0000 1.3300
1/4 0.2500 20 28 0.2500 0.2435 0.5310 0.4800 0.4240 0.4230 0.0640 0.0430 0.1610 5/32 0.1560 0.1110 1.0000 1.5000
5/16 0.3125 18 24 0.3125 0.3053 0.6560 0.6000 0.5390 0.5380 0.0700 0.4700 0.1980 3/16 0.1880 0.1350 1.1250 1.7100
3/8 0.3750 16 24 0.3750 0.3678 0.7810 0.7200 0.6530 0.6520 0.0760 0.0500 0.2340 7/32 0.2190 0.1590 1.2500 1.9400
7/16 0.4375 14 20 0.4375 0.4294 0.8440 0.7810 0.6900 0.6890 0.0920 0.0630 0.2340 1/4 0.2500 0.1590 1.3750 2.1700
1/2 0.5000 13 20 0.5000 0.4919 0.9380 0.8720 0.7390 0.7380 0.1190 0.0870 0.2510 5/16 0.3120 0.1720 1.5000 2.3800
5/8 0.6250 11 18 0.6250 0.6163 1.1880 1.1120 0.9620 0.9610 0.1350 0.0960 0.3240 3/8 0.3750 0.2200 1.7500 2.8200
3/4 0.7500 10 16 0.7500 0.7406 1.4380 1.3550 1.1860 1.1850 0.1500 0.1050 0.9600 1/2 0.5000 0.2200 2.0000 3.2500
7/8 0.8750 9 14 0.8750 0.8647 1.6880 1.6040 1.4110 1.1410 0.1650 0.1180 0.4680 9/16 0.5620 0.2480 2.2500 3.6900
1 1.0000 8 14 1.0000 0.9886 1.9380 1.8410 1.6350 1.6340 0.1810 0.1300 0.5400 5/8 0.6250 0.2970 2.5000 4.1200
1 1/8 1.1250 7 12 1.1250 1.1086 2.1880 2.0790 1.8590 1.8580 0.1960 0.1400 0.6110 3/4 0.7500 0.3250 2.8100 4.6500
1 1/4 1.2500 7 12 1.2500 1.2336 2.4380 2.3160 2.0830 2.0820 0.2120 0.1500 0.6830 7/8 0.8750 0.3580 3.1200 5.0900
1 3/8 1.3750 7 12 1.3750 1.3568 2.6880 2.5530 2.3060 2.3050 0.2280 0.1620 0.7550 7/8 0.8750 0.4020 3.4400 5.6500
1 1/2 1.5000 6 12 1.5000 1.4818 2.9380 2.7910 2.5300 2.5290 0.2430 0.1730 0.8270 1 1.0000 0.4350 3.7500 6.0800
  1. All dimensions are in inches.
18-8 SS Flat Socket Cap Screw
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Diameter Thread Pitch Length Item # Availability Price Quantity UOM
#4 40 3/4 SFLS 40075 In Stock $0.12014/EA EA
#6 32 1/4 SFLS 60025 In Stock $0.04325/EA EA
#6 32 1/2 SFLS 60050 In Stock $0.04005/EA EA
#6 32 3/4 SFLS 60075 In Stock $0.0801/EA EA
#8 32 1/4 SFLS 80025 In Stock $0.05847/EA EA
#8 32 3/8 SFLS 80037 In Stock $0.05567/EA EA
#8 32 1/2 SFLS 80050 3-5 Working Days $0.10344/EA EA
#8 32 3/4 SFLS 80075 In Stock $0.09095/EA EA
#10 24 1/2 SFLS1020050 In Stock $0.10925/EA EA
#10 24 5/8 SFLS1020062 In Stock $0.12014/EA EA
#10 24 3/4 SFLS1020075 In Stock $0.12038/EA EA
#10 24 1 SFLS1020100 In Stock $0.14754/EA EA
#10 24 1 1/4 SFLS1020125 In Stock $0.19872/EA EA
#10 24 1 1/2 SFLS1020150 In Stock $0.1159/EA EA
#10 32 3/4 SFLS1030075 In Stock $0.08034/EA EA
#10 32 1 SFLS1030100 In Stock $0.13773/EA EA
#10 32 1 1/4 SFLS1030125 In Stock $0.17461/EA EA
#10 32 1 1/2 SFLS1030150 In Stock $0.21682/EA EA
1/4 20 5/8 SFLS0250062 In Stock $0.13616/EA EA
1/4 20 3/4 SFLS0250075 In Stock $0.12863/EA EA
1/4 20 1 SFLS0250100 In Stock $0.18366/EA EA
1/4 20 1 1/4 SFLS0250125 In Stock $0.22347/EA EA
1/4 20 1 1/2 SFLS0250150 In Stock $0.2704/EA EA
1/4 20 1 3/4 SFLS0250175 In Stock $0.28146/EA EA
1/4 20 2 SFLS0250200 In Stock $0.28843/EA EA
5/16 18 3/4 SFLS0310075 In Stock $0.21518/EA EA
5/16 18 1 SFLS0310100 In Stock $0.27942/EA EA
5/16 18 1 1/4 SFLS0310125 In Stock $0.31798/EA EA
5/16 18 1 1/2 SFLS0310150 In Stock $0.39636/EA EA
5/16 18 1 3/4 SFLS0310175 In Stock $0.59768/EA EA
5/16 18 2 SFLS0310200 In Stock $0.52062/EA EA
3/8 16 1/2 SFLS0370050 In Stock $0.56067/EA EA
3/8 16 3/4 SFLS0370075 In Stock $0.40689/EA EA
3/8 16 1 SFLS0370100 In Stock $0.50084/EA EA
3/8 16 1 1/4 SFLS0370125 In Stock $0.51217/EA EA
3/8 16 1 1/2 SFLS0370150 In Stock $0.64473/EA EA
3/8 16 1 3/4 SFLS0370175 In Stock $0.62399/EA EA
3/8 16 2 SFLS0370200 In Stock $0.92395/EA EA
3/8 16 2 1/4 SFLS0370225 In Stock $1.69203/EA EA
3/8 16 2 1/2 SFLS0370250 In Stock $0.92976/EA EA
3/8 16 3 SFLS0370300 In Stock $0.80096/EA EA
3/8 16 4 SFLS0370400 In Stock $3.91137/EA EA
1/2 13 3/4 SFLS0500075 In Stock $0.88106/EA EA
1/2 13 1 SFLS0500100 In Stock $0.81738/EA EA
1/2 13 1 1/2 SFLS0500150 In Stock $1.02303/EA EA
1/2 13 1 3/4 SFLS0500175 In Stock $1.50761/EA EA
1/2 13 2 SFLS0500200 In Stock $1.16268/EA EA
1/2 13 2 1/2 SFLS0500250 In Stock $2.11073/EA EA
1/2 13 3 SFLS0500300 In Stock $1.93528/EA EA
5/8 11 1 SFLS0620100 In Stock $2.14658/EA EA
5/8 11 1 1/4 SFLS0620125 In Stock $2.44293/EA EA
5/8 11 1 1/2 SFLS0620150 In Stock $3.80457/EA EA
5/8 11 1 3/4 SFLS0620175 In Stock $4.4688/EA EA
5/8 11 2 SFLS0620200 In Stock $4.09091/EA EA
5/8 11 2 3/4 SFLS0620275 In Stock $5.2463/EA EA
5/8 11 3 SFLS0620300 In Stock $5.28634/EA EA
5/8 11 3 1/2 SFLS0620350 In Stock $5.68682/EA EA
3/4 10 1 3/4 SFLS0750175 In Stock $6.84822/EA EA
3/4 10 2 1/2 SFLS0750250 In Stock $10.02535/EA EA
3/4 10 3 1/2 SFLS0750350 In Stock $14.4489/EA EA