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ASTM F879 Specification

ASTM F879 - Standard Specification for Stainless Steel Socket Button and Flat Countersunk Cap Screws.

This specification covers chemical and mechanical requirements for stainles steel inch (imperial) series hexagon socket button cap screws (SBHCS) and flat countersunk head screws/socket flat head cap screws (SFHCS) with nominal thread diameter 0.060 through 0.625 inch., intended for use in. ASTM F879M is a companion to ASTM F879 developed for metric sizes SBHCS and SFHCS from M1.6 to M16. Three property conditions are covered: austenitic alloy group 1 in as annealed condition (AF) at 85 ksi maximum, in two cold worked conditions (CW) at 80 ksi minimum and (CW1) at 102 ksi minimum. Ferrobend manufactures socket button head cap screws and flat countersunk head screws as per both specifications duly tested and supplied with EN 10204 Type 3.1 Certification. We produced almost all grades under this specification, 304, 304L, 316 and 316L being most offered alloys.

ASTM F879 Chemical Composition

Composition, & maximum except as shown
UNS Designation Alloy Carbon Manganese Phosphorus Sulfur Silicon Chromium Nickel Copper Molybdenum
Austenitic Alloys
S30400 304 0.08 2.00 0.045 0.03 1 18.0 - 20.0 8.0 - 10.5 1.00 --
A30403 304L 0.03 2.00 0.045 0.030 1 18.0 - 20.0 8.0 - 12.0 1.00 --
S30500 305 0.12 2.00 0.045 0.03 1 17.0 - 19.0 10.5 - 13.0 1.00 --
S38400 384 0.08 2.00 0.045 0.030 1 15.0 - 17.0 17.0 - 19.0 -- --
S30430 18-9LW 0.10 2.00 0.045 0.030 1 17.0 - 19.0 8.0 - 10.0 3.0 - 4.0 --
S30433 302HQ 0.03 2.00 0.045 0.030 1 17.0 - 19.0 8.0 - 10.0 3.0 - 4.0 --
S31600 316 0.08 2.00 0.045 0.030 1 16.0 - 18.0 10.0 - 14.0 -- 2.0 - 3.0
S31603 316 L 0.03 2.00 0.045 0.030 1 16.0 - 18.0 10.0 - 14.0 -- 2.0 - 3.0

ASTM F879 Mechanical Properties

Condition Full Size ProductA Machined Specimen Core HardnessB
Tensile Strength, ksi Minimum ExtensionC Tensile Strength, ksi Yield Strength, ksi Minimum Elongation, % Vickers Rockwell
AF 85 max 0.6D 85 max 55 max 40 210 max 95 HRB max
CW 80 min 0.4D 80 min 40 min 25 150 min 50 HRA min
CW1 102 min 0.4D 87 min 65 min 20 220 min 59 HRA min

A Actual full size testing of condition CW and CW1 may result in decreased tensile strength because of the head configuration. For fasteners with nominal thread diameters larger than 0.625 inch, the mechanical properties shall be agreed upon between the user and the manufacturer.
B Core hardness is only required when full size product tensile testing cannot be accomplished.
C D denoted nominal thread size.

ASTM F879 Tensile Strength Values for Full Size Fasteners, lbs

Nominal Size Stress Area Alloy Group 1, lbs, min
AF CW CW1
0 0.060-80 0.0018 153 115 147
1 0.073-64 0.00263 223 168 215
2 0.086-56 0.00370 314 237 303
3 0.099-48 0.00487 414 312 399
4 0.112-48 0.00604 513 386 495
5 0.125-40 0.00796 676 509 652
6 0.138-32 0.00909 772 581 745
8 0.164-32 0.01400 1191 897 1149
10 0.190-24 0.01750 1490 1122 1438
1/4" 0.250-20 0.03180 2705 2037 2609
5/16" 0.312-18 0.05240 4457 3356 4299
3/8" 0.375-16 0.07750 6 587 4959 6354
1/2" 0.500-13 0.14190 12061 9082 11636
5/8" 0.625-11 0.22600 19210 14464 18532