Cyfansoddiad cemegol GB 3087 Gradd 20
| Gradd | Cyfansoddiad Cemegol(%) | |||||||
| C | Os | Mn | P | S | Cr | Cu | Ni | |
| 20 | 0.17-0.23 | 0.17-0.37 | 0.38-0.65 | Llai na neu'n hafal i 0.030 | Llai na neu'n hafal i 0.030 | 0.3-0.65 | Llai na neu'n hafal i 0.25 | Llai na neu'n hafal i 0.30 |
Priodweddau mecanyddol GB 3087 Gradd 20
| Gradd | trwch wal (mm) |
Cryfder tynnol (MPa) |
Cryfder Cynnyrch (MPa) |
Ymuniad % |
| Yn fwy na neu'n hafal i | ||||
| 20 | ＜15 | 410-550 | 245 | 20 |
| Yn fwy na neu'n hafal i 15 | 225 | |||
Gwyriad a ganiateir o ddiamedr allanol a thrwch wal
| Math o bibell ddur | Diamedr allanol (mm) | Goddefgarwch | ||
| cyffredin | uwch | |||
| Tiwb rholio poeth | OD | Llai na neu'n hafal i 159 | �% B110%(min�% B10.50mm) | ±{{0}}}.75%(min±0.40mm) |
| ＞159 | ±1.0% | ±0.90% | ||
| WT | Llai na neu'n hafal i 20 | ＋15.0%(min＋0.45mm) －12.5% －0.35mm) |
±10%(min±0.30mm) | |
| ＞20 | ±12.5% | ±10% | ||
| OD Yn fwy na neu'n hafal i 351 | ±15% | |||
| Tiwb wedi'i dynnu'n oer | OD | 10-30 | �% B1% 7B{0}}.40mm | �% B1% 7b{0}}.20mm |
| ＞30-50 | �% B1% 7b{0}}.45mm | %c2%b1%7b%7b0%7d%7d.25mm | ||
| ＞50 | ±1.0% | ±0.75% | ||
| WT | 1.5-3.0 | +15% -10% |
±10% | |
| ＞3.0 | +12.5% -10% |
±10% | ||
