| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|
| Grade | Properties of finished bolts | ||||||
| Mimimum tensile strength See Note 1 |
Mimimum yeild stress. See Note 2 |
Mimimum elongation on a gauge length 4√area See Note 3 |
Minimum izod impact value | Brinell hardness number. See Note 4 |
|||
| Diameter or width across flats | |||||||
| Up to ¾ in |
Over ¾ in up to and including 1⅛ in |
Over 1⅛ in |
|||||
| tonf/in | tonf/in | per cent | tf lbf | tf lbf | tf lbf | HB10/3000 | |
| A | 28 | -- |
10
14
} See Note 4
|
-- | -- | -- | -- |
| B | 28 | -- | 17 | -- | -- | -- | -- |
| P | 35 | -- | 15 | 20 | 15 | 10 | 152/240 |
| R | 45 | 34 | 20 | 40 | 35 | 25 | 201/285 |
| T | 55 | 41 | 16 | 35 | 30 | 20 | 248/335 |
| V | 65 | 52 | 14 | 35 | 30 | 20 | 293/370 |
| X | 75 | 63 | 12 | 15 | 15 | 15 | 341/410 |
Note 1. When the ultimate tensile and yeild stress tests are made on a bolt or screw, the mehod employed shall be as follows: An ordinary nut or its equivalent in the form of an adaptor shall be screwd onto the bolt or screw so as to be clear of any imperfect threads at the point. The load shall then be aplied to the head and to the nut or adaptor. In the calculations the cross-sectional area of the thread shall be based on the formula:
Area = π × ((BasicEffectiveDiameter² + BasicMinorDiameter²) / 4)
Note 2. The yeild stress values given shal not be used as acceptance value except by special arrangement between the purchaser and the manufacturer. It frequently happens, espacially with steels of tensile strength over 50 tonf/in, that the yeild point is ill-defined. In the case of a steel which does not show a well-defined yeild point , the yeild point is to be intrepreted as the 'Proof stress' corresponding to 0.5 per cent permanent elongation. * As specified for the thread in question in B.S. 84, Parallel screw threads of Whitworth form.
Note 3. B.S. 18, Methods for tensile testing of metals, noew specifies a guagew length of 5.65√area, but elongation values appropriate to this length are not yet available for the higher grades of steel. The Values in Column 4 have therefore been retained pending further information on the subject.
Note 4. For Grade A bolts or screwws the mimimum elongation shall be 10 per cent for ¾ in and ⁵⁄₁₆ in nomial sizes and 14 per cent for all other sizes up to and including 2 in.
Note 5. For bolts and screws below ½ in diameter a notched fracture test may be substiuted for the Izod impact test (see B.S.131, 'Methods for notched bar tests', Part 1, 'The Izod impact test on metals ')
Note 6. Brinell hardness numbers are given for guidance only and a hardness test in not part of the requirements of the standard. When a Brinell hardness test is made, it is carried out in accordance with the method specified in B.S. 240, 'Method for Brinell hardness test', Part 1, 'Testing of metals'. and is made on the top of the head or on the point of the bolt or screw.