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This part of ISO 898 specifies mechanical and physical properties of set screws and similar threaded fasteners
made of carbon steel or alloy steel when tested at an ambient temperature range of 10 °C to 35 °C. Fasteners (the
term used when set screws and similar threaded fasteners are considered all together) which conform to the
requirements of this part of ISO 898 are evaluated at that ambient temperature range.
Fasteners in conformance with this part of ISO 898 are classified to specified hardness classes and are
intended for use under compressive stress only.
| Hardness class | Material | Heat treatment,a | Chemical composition limit (cast analysis,%)b | |||
|---|---|---|---|---|---|---|
| c | p max. | s max. | ||||
| max. | min. | |||||
| 14H | Carbon steel c | – | 0,50 | – | 0,11 | 0,15 |
| 22H | Camon stee1 d | Quenched and tempered | 0,50 | 0,19 | 0,05 | 005 |
| 33H | Carbon steel d | Quenched and tempered | 0,50 | 0,19 | 0,05 | 0,05 |
| 45H | Carbon stee1 de | Quenched and tempered | 0,50 | 0,45 | 0,05 | 0,05 |
| Carbon stee lwith additives, d (e.g.Boron or Mn or Cr) | Quenched and tempered | 0,50 | 0,28 | 0,05 | 0,05 | |
| Alloy stee1 df | Quenched and tempered | 0,50 | 0,30 | 0,05 | 0,05 | |
Note:
a. Case hardening is not allowed.
b. In case of dispute, the product analysis applies.
c. Free-cutting steel may be used, with maximum lead content 0,35 %, maximum phosphorus content 0,11 % and maximum sulfur
content 0,34 %.
d. Steel with a maximum lead content of 0,35 % may be used.
e. For d ≤ M16 only.
f. This alloy steel shall contain at least one of the following elements in the minimum quantity given: chromium 0,30 %, nickel
0,30 %, molybdenum 0,20 %, vanadium 0,10 %. Where elements are specified in combinations of two, three or four and have lower
alloy contents than those given above in this footnote, the limit value to be applied for steel class determination is 70 % of the sum of
the individual limit values shown above in this footnote for the two, three or four elements concerned.
| No. | Mechanical and phys ical properties | Hardness class | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 14H | 22H | 33H | 45H | ||||||
| 1 | Performance hardness | ||||||||
| 1.1 | Vickers hardness,HV 10 | min. | 140 | 220 | 330 | 450 | |||
| max. | 290 | 300 | 440 | 560 | |||||
| 1.2 | Brinell hardness HBW,F = 30 D2 | min. | 133 | 209 | 314 | 428 | |||
| max. | 276 | 285 | 418 | 532 | |||||
| 1.3 | Rockwell hardness | HRB | min. | 75 | 95 | – | – | ||
| max. | 105 | a | – | – | |||||
| HRC | min. | – | a | 33 | 45 | ||||
| max. | – | 30 | 44 | 53 | |||||
| 2 | Torque strength | – | – | – | |||||
| 3 | Height of non-decarburized thread zone,£, mm | min. | – | 1/2H1 | 2/3H1 | 3/4H1 | |||
| 4 | Depth of complete decarburization,G, mm | max. | – | 0,015 | 0,015 | b | |||
| 5 | Surface hardness HV 0,3 (see 9.1.3) | max. | – | 320 | 450 | 580 | |||
| 6 | Non-carburization, HV 0,3 | max. | c | c | c | ||||
| 7 | Surface integrity in accordance with | ISO 6157-1 | |||||||
Note:
a. For hardness class 22H: if hardness is tested in Rockwell, it is necessary to test the minimum value in HRB and the maximum
value in HRC.
b. No complete decarburization permitted in hardness class 45H.
c. Surface hardness shall not be more than 30 Vickers points above the measured base metal hardness of the fastener when
determination of both the surface hardness and base metal hardness are carried out with HV 0,3.
| Nominal thread diameter (coarse and fine pitch) | Minimumlength of hexagonal socket set screw for test,a mm | Proof torque Nm | |||
|---|---|---|---|---|---|
| Flat point | Cone point | Dog point | Cup point | ||
| 3 | 4 | 5 | 6 | 5 | 09 |
| 4 | 5 | 6 | 8 | 6 | 25 |
| 5 | 6 | 8 | 8 | 6 | 5 |
| 6 | 8 | 8 | 10 | 8 | 85 |
| 8 | 10 | 10 | 12 | 10 | 20 |
| 10 | 12 | 12 | 16 | 12 | 40 |
| 12 | 16 | 16 | 20 | 16 | 65 |
| 16 | 20 | 20 | 25 | 20 | 160 |
| 20 | 25 | 25 | 30 | 25 | 310 |
| 24 | 30 | 30 | 35 | 30 | 520 |
| 30 | 36 | 36 | 45 | 36 | 860 |
Note:
a. For hexalobular socket set screws, there is no requirement for minimum length (as tmin of the socket is the same for all lengths).