ASTM F837 Stainless Steel Socket Head Cap Screws
The stainless socket head cap screw specification: 304-group and 316-group alloys annealed or cold worked, or 410 hardened and tempered to 180 ksi, passivated and dimensioned to ASME B18.3 — the corrosion-resistant counterpart of A574.
What F837 is.
ASTM F837 covers stainless steel socket head cap screws in inch sizes from 0.060 in. (#0) to 1-1/2 in., with F837M the metric counterpart. Austenitic screws are ordered by alloy group and condition: Group 1 (304 and related alloys) or Group 2 (316 and 316L), each annealed (AF) or cold worked (CW or CW1). Group 5 is martensitic 410, hardened and tempered (HT) to 180 ksi minimum. Within a group the manufacturer may choose the alloy unless alloy control (Supplementary Requirement S2) is ordered, and the alloy used must be shown on the certification.
Bar for Groups 1 and 2 must be capable of passing the ASTM A262 Practice E intergranular corrosion test, and finished screws are cleaned, descaled and passivated to ASTM A380 or A967. Threads up to 1 in. diameter and 6 in. long are rolled; heads may be hot forged, cold forged or machined. We machine F837 socket head cap screws in special lengths, drilled heads and threads from certified 304 and 316 bar.
Chemical composition.
| Element | 304 (Gr 1) | 304L (Gr 1) | 316 (Gr 2) | 316L (Gr 2) | 410 (Gr 5) |
|---|---|---|---|---|---|
| Carbon, max | 0.08 | 0.030 | 0.08 | 0.03 | 0.15 |
| Manganese, max | 2.00 | 2.00 | 2.00 | 2.00 | 1.00 |
| Phosphorus, max | 0.045 | 0.045 | 0.045 | 0.045 | 0.040 |
| Sulfur, max | 0.030 | 0.030 | 0.030 | 0.030 | 0.030 |
| Silicon, max | 1.00 | 1.00 | 1.00 | 1.00 | 1.00 |
| Chromium | 18.0–20.0 | 18.0–20.0 | 16.0–18.0 | 16.0–18.0 | 11.5–13.5 |
| Nickel | 8.0–10.5 | 8.0–12.0 | 10.0–14.0 | 10.0–14.0 | — |
| Molybdenum | — | — | 2.0–3.0 | 2.0–3.0 | — |
Percent maximum unless a range is shown. Group 1 also includes 303 (free-machining, only with purchaser approval), 305, 384, XM1, 18-9LW, 302HQ and 304J3. Up to 1.00 % copper is permitted in 304, 304L and 305 at the manufacturer’s option for formability.
Mechanical properties.
| Group · condition (nominal dia., in.) | Marking | Full-size tensile (ksi) | Extension, min | Machined tensile (ksi) | Yield 0.2 % (ksi) | Elongation, min (%) | Core hardness |
|---|---|---|---|---|---|---|---|
| Group 1 or 2 · AF (0.060–1.500) | F837A · F837D | 85 max | 0.60 D | 85 max | 55 max | 40 | 210 HV max · 95 HRB max |
| Group 1 or 2 · CW (0.060–0.750) | F837B · F837E | 80 min | 0.40 D | 80 min | 40 min | 25 | 150 HV min · 50 HRA min |
| Group 1 or 2 · CW1 (0.060–0.750) | F837C · F837F | 102 min | 0.40 D | 87 min | 65 min | 20 | 220 HV min · 59 HRA min |
| Group 5 · HT (0.060–0.190) | F837G | 180 min | — | — | — | — | 350–423 HV · 36–43 HRC |
| Group 5 · HT (0.250–1.500) | F837H | 180 min | 0.20 D | 160 min | 120 min | 12 | 350–423 HV · 36–43 HRC |
Hardness is tested on every lot, plus either full-size tests (tensile and extension) or machined-specimen tests (tensile, yield, elongation); full-size results decide in arbitration. Core hardness applies only when full-size tensile testing cannot be done. CW and CW1 above 0.750 in.: properties and marking by agreement. D = nominal diameter.
Specifications that apply.
How F837 ships from Houston.
- Socket head cap screws, 0.060 in. (#0) to 1-1/2 in.
- Special lengths and drilled or cross-drilled heads
- 410 hardened and tempered screws (Group 5 HT)
- Machined specials to drawing
F837 fasteners we make.
Every item is manufactured to your drawing or standard in F837, imperial or metric, with an EN 10204 3.1 certificate.
Testing, certification and marking
- Hardness on every lot, plus full-size or machined-specimen tensile tests per Table 3
- Screws 1/4 in. and larger marked with the manufacturer’s symbol and the F837 grade mark (F837A to F837H)
- Group 1 and 2 bar capable of passing ASTM A262 Practice E
- Test report and certificate of conformance kept on file for 5 years, copies on request
- Optional supplementary requirements include shipment lot testing (S1), alloy control (S2), permeability limits (S3), cold-forged heads (S6) and corrosion testing (S7)
ASTM A574 Alloy Steel Socket Head Cap Screws (170–180 ksi)
The socket head cap screw specification: alloy steel quenched and tempered to 180 ksi in ½ in. and smaller and 170 ksi above, 37 to 44 HRC, black oxide — the standard for tooling, machinery and die work.
ASTM F879 · ASME B18.3ASTM F879 Stainless Steel Socket Button and Flat Head Cap Screws
The stainless low-head socket screws: button and flat countersunk heads in 304 or 316, annealed at 85 ksi maximum or cold worked to 80 and 102 ksi minimum, passivated.
ASTM A276 bar · ASTM F593 bolts304 Stainless Steel (UNS S30400)
The general-purpose 18-8 stainless: 75 ksi annealed bar, cold-worked bolts to 160 ksi, non-magnetic, and resistant to water, food and most mild chemicals.