25 B级小半圆头低方颈螺栓GB/T 801—1998标准
B级小半圆头低方颈螺栓GB801—1998标准
B级小半圆头低方颈螺栓的尺寸规格、质量见表4.1-47和表4.1-48。
表4.1-47 B级半圆头低方颈螺栓的尺寸规格（mm)
| 螺纹规格d | M6 | Mg | M10 | M12 | |
| b | 18 | 22 | 26 | 30 | |
| dk | max | 13.1 | 17.1 | 21.3 | 25.3 |
| min | 11.3 | 15.3 | 19.16 | 23.16 | |
| k1 | max | 3.4 | 3.4 | 4.4 | 5.4 |
| min | 2.6 | 2.6 | 3.6 | 4.6 | |
| k | max | 4.08 | 5.28 | 6.48 | 8.9 |
| min | 3.2 | 4.4 | 5.6 | 7.55 | |
| Ss | max | 6.3 | 8.36 | 10.36 | 12.43 |
| min | 5.84 | 7.8 | 9.8 | 11.76 | |
| r min | 0.5 | 0.5 | 0.5 | 0.8 | |
| R | 7 | 9 | 11 | 13 | |
| x max | 2.5 | 3.2 | 3.8 | 4.2 | |
| l ① | 16-60 | 35-80 | 40-100 | 45-120 | |
①公称长度系列：16、20-70(5进级）、80-120mm (10 mm进级）。
表4.1-48 B级半圆头低方颈螺栓的质量（kg)
| 每1000件钢制品的大约质量 | |||||||
| l | G | l | G | l | G | l | G |
| M6 | M8 | M10 | M12 | ||||
| 16 | 4.48 | 35 | 14.88 | 40 | 27.59 | 45 | 48.39 |
| 20 | 5.16 | 40 | 16.44 | 45 | 30.05 | 50 | 51.95 |
| 25 | 6.02 | 45 | 17.99 | 50 | 32.5 | (55) | 55.51 |
| 30 | 6.88 | 50 | 19.55 | (55) | 34.96 | 60 | 59.07 |
| 35 | 7.73 | (55) | 21.1 | 60 | 37.42 | (65) | 62.64 |
| 40 | 8.59 | 60 | 22.66 | (65) | 39.87 | 70 | 66.2 |
| 45 | 9.45 | (65) | 24.21 | 70 | 42.33 | 80 | 73.32 |
| 50 | 10.31 | 70 | 25.77 | 80 | 47.24 | 90 | 80.45 |
| (55) | 11.16 | 80 | 28.88 | 90 | 52.15 | 100 | 87.57 |
| 60 | 12.02 | 100 | 57.06 | 110 | 94.7 | ||
| 120 | 101.8 | ||||||
注：尽量不采用括号内的规格。