ISO 16872:2015 pdf download

ISO 16872:2015 pdf download.Round steel short link chains for lifting purposes — Fine tolerance hoist chains for hand operated chain hoists — Grade VH
6.4.6 Toughness
The toughness of the finished hoist chain shall be verified by impact test method on full-size, subsize, or super subsize specimens. The lowest service temperature (T) of the hoist chain shall be T ≥ T NDT − 20K, as a result of ISO/TR 23602. Based on a correlation between KV shift and the T NDT shift, a KV − T master curve with the requirement of KV (0 °C) ≥ 45 J results in a value T NDT − 20K of ≤ −10 °C. Therefore, a lowest temperature during the operation of −10 °C is possible. Full-size specimens shall be tested in accordance with ISO 148-1. On the other hand, subsize specimens shall be tested in accordance with ISO 14556. If the chain leg is too short to extract a full-length subsize specimen, the subsize specimens shall be produced according to Figure 3 by joining additional leg parts using laser welding. Super subsize specimens shall then be tested in accordance with ISO 14556, except that the specimen dimensions shall be in accordance with Figure 4. Super subsize specimens shall be produced by joining additional leg parts using pulsed micro-laser welding. The settings for laser welding and pulsed micro-laser welding shall be such that the hardness and micro-structure of the specimen are not affected in the area of the notch. After welding, the specimens shall be machined to the specified dimensions. Either pendulum impact type or drop weight type test equipment may be used, taking account of the accuracy of measurement of the toughness value.
If the chain link is large enough to extract a full-size specimen, the tests shall be carried out on full-size specimens. Three specimens shall be tested, each of which shall achieve a KV toughness of at least 45 J at a test temperature of 0 °C. If the chain link is too small to extract a full-size specimen but large enough to extract a subsize specimen or a welded on subsize specimen, the tests shall be carried out on subsize specimens, which shall achieve a KV toughness of at least 3,5 J at a test temperature of 0 °C. To ensure that the distance of the test temperature to the brittle-tough-transition temperature is sufficient, KV toughness 3,5 J shall be 1/2 E US +1 J [half upper shelf energy (USE) +1 J] or more. The test shall be carried out on 10 specimens, and the mean value used as the KV toughness value. The range of scattering shall be within 1,5 J. If the chain link is too small to extract a subsize specimen, the tests shall be carried out on super subsize specimens extracted from the chain and full-size specimens made of the same material as the chain, which is heat treated so as to achieve the same ultimate tensile strength of hardness and material as the finished hoist chain. Three full-size specimens shall be tested, each of which shall achieve a KV toughness of at least 45 J at a test temperature of 0 °C. Three super subsize specimens shall be tested and shall show 80 % or more non-crystalline area when tested at −50 °C. NOTE It is assumed that the transition temperature is −50 °C or lower in that case. The above-mentioned tests shall be repeated if the steel manufacturer or type of steel is changed or the chain manufacturer changes the manufacturing process.