Chemical composition of material of screws
Chemical composition of material of screws
The table contains information on the chemical composition of steels for the manufacture of bolts devided by classes of strength. Chemical composition of materials is binding only on those bolts that can not be tested by tensile test.
Table according by standard ISO 898-1 (EN 20898)
| Strengthclass | Materials | Chemical composition % | Tempering temperature | |||
| C min. | C max. | P max. | S max. | |||
| 3.61) | Carbon steel | - | 0,20 | 0,05 | 0,06 | - |
| 4.61) | - | 0,55 | 0,05 | 0,06 | ||
| 4.81) | ||||||
| 5.6 | 0,15 | 0,55 | 0,05 | 0,06 | ||
| 5.81) | - | 0,55 | 0,05 | 0,06 | ||
| 6.81) | ||||||
| 8.82) | Carbon steel with additives B, Mn, or Cr, case-hardened and tempered | 0,153) | 0,40 | 0,035 | 0,035 | 425 |
| Carbon steel, case-hardened andtempered | 0,25 | 0,55 | 0,035 | 0,035 | ||
| 9.8 | Carbon steel with additives B, Mn, or Cr, case-hardened and tempered | 0,153) | 0,035 | 0,035 | 0,035 | 425 |
| Carbon steel, case-hardened andtempered | 0,25 | 0,55 | 0,035 | 0,035 | ||
| 10.94) | Carbon steel with additives B, Mn, or Cr, case-hardened and tempered | 0,153) | 0,35 | 0,035 | 0,035 | 340 |
| 10.95) | Carbon steel, case-hardened andtempered | 0,25 | 0,55 | 0,035 | 0,035 | 425 |
| Carbon steel with additives B, Mn, or Cr, case-hardened and tempered | 0,203) | 0,55 | 0,035 | 0,035 | ||
| Carbon steel, case-hardened andtempered | 0,20 | 0,55 | 0,035 | 0,035 | ||
| 12,95) 6) | Carbon steel, case-hardened andtempered | 0,20 | 0,50 | 0,035 | 0,035 | 380 |
- Strength for these classes is permissible automat steel with the following maximum shares of S, P and Pb: S = 0.34%, P = 0.11%, Pb = 0.35%.
- For nominal diameter over 20 mm it is necessary to use the material strength class 10.9 for reasons of sufficient hardness.
- Carbon steel with additives B and C content less than 0.25% (according tavebního analysis) Mn content must be at least class 8.8 0.6% for class 9.8 and 10.9 at least 0.7%.
- For articles of these steels must be label-class strength underlined.
- Material for this property class must be sufficiently hardened to be sure that the composition of the nucleus in the threaded part will be available approximately 90% of blindness in the martensite state before tempering.
- For strength class 12.9 is admissible metallographically detectable white phosphorousenriched layer on the surface, which is tension.
- Alloy steel must contain at least one of the following elements: Cr, Ni, Mb, Va.
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