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 |