Procuroment rules for hexagon nut
[ Time：2021-07-23 Click：3539 ]
NUTS
1 Chemical composition test
Within a specified time,incoming nuts materials of grade 35CrMo shall be retest, and results must be in accordiance with TABLE 1.
TABLE 1-1 Chemical composition of nuts(mass fraction)) /%
| Grade | C | Si | Mn | Cr | Mo | P | S |
| 35CrMo | 0.32～0.40 | 0.17～0.37 | 0.40～0.70 | 0.80-1.10 | 0.15-0.25 | ≤0.035 | ≤0.035 |
TABLE 1-2 Permissible tolerances for Chemical composition tolerances/%
| C | Si | Mn | P、S | Cr | Mo |
| ±0.02 | ±0.02 | ±0.03 | +0.005--0.00 | ±0.05 | ±0.01 |
1.2 Appearance inspection
Visual inspection and rule measurement shall be used to inspect surface discontinuities of nuts, and results must be in accordiance with TABLE 2.
TBALE 2 Surface discontinuities of nuts
| Nuts grade | Standard | Voids | Quench cracks | Seams | Forging cracks | Folds |
| 810 | GB/T5779.2-2000 | ≤0.25mm | not be permitted | ≤0.05D | ≤0.05Dnot more than two forging cracks | permitted |
D——nominal thread diameter
1.3 Dimension and tolerances inspection
Dimension and tolerance inspection shall be in accordiance with GB/T6170-2000 "Hexagon regulat nuts(style 1)". See Table 3 thickness m is symboled and described.
Table 3 Thickness of nuts
| Specification of nuts | M30 | M36 | M42 | M48 | M56 | M64 | ||
| Pitch P | 3.5 | 4 | 4.5 | 5 | 5.5 | 6 | ||
| Q/AYLT 06-2016 | THmm
|
max | 31.5 | 38.5 | 42.0 | 47.0 | 56.0 | 63.0 |
| min | 30.0 | 37.0 | 38.0 | 45.5 | 54.0 | 61.0 | ||
1.4 Manufacturing method of nuts
Nuts are forged from hot-rolled steel round bars, internal thread machined by screw tap.
1.5 Cone proof load inspection
Cone proof load test on nuts shall be calculated by As(stress area)×Sp(stress under proof load). Sp numerical value of grade 10 style 1 nuts shall be 1060N/mm².
1.6 Hardness inspection
Hardness of nuts, nominal stress area in thread and cone proof load of threads shall be in accordiance with Table 4,
Table 4 Property of nuts
| Spc. | cone proof load KN | Hardness | Nominal stress area in thread mm2 | ||
| Gr. 8级 | Gr.10级 | Gr.8 | Gr.10 | ||
| M30 | 538.56 | 594.66 | HV233-353
HRC 21.5-37.0
|
HV272-353
HRC 28.5-37.0 |
561 |
| M36 | 784.32 | 866.02 | 817 | ||
| M39 | 936.96 | 1034.56 | 976 | ||
| M42 | 1075.2 | 1187.20 | 1120 | ||
| M48 | 1411.2 | 1558.20 | 1470 | ||
| M56 | 1948.8 | 2151.80 | 2030 | ||
| M64 | 2572.8 | 2840.80 | 2680 | ||
| washers | HRC 35.0-45.0 | ||||
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