HB 7401-2021 in English

Scope

The specimens of this standard are weighing specimens, which can be mechanical properties specimens or accompanying specimens. Mechanical properties specimens are specimens used for mechanical properties testing. When there are no accompanying specimens, mechanical properties specimens (without reinforcement sheets, without fasteners, and a mass of not less than 5 grams) can be used as weighing specimens, not less than 3. The accompanying specimens selected should be consistent with the ply form and thickness of the mechanical properties specimens, and prepared in the same furnace and batch as the mechanical properties specimens. The generally recommended size of the accompanying specimens is 25mm×25mm, 50mm×50mm or 100mm×100mm. Take 3 accompanying specimens for each batch and each identified test plate. The mass of the weighing specimen is not less than 5g. The thickness of the weighing specimen does not vary by more than ±5% over the entire surface. The geometric dimensions and shape of the weighing specimen are: when the weighing specimen is a mechanical properties specimen without reinforcement sheets and fasteners, its geometric dimensions and shape are consistent with the mechanical properties specimen. When the weighing specimen is an accompanying specimen, the selection principle is to refer to the geometric dimensions of the specimen for the mechanical properties test state adjustment, and the size of the accompanying specimen should not be less than the width of the mechanical properties test specimen. When sealing the four sides of the accompanying sample, the size of the accompanying sample can be selected as 25mm±2mm. The sample preparation is carried out according to the requirements of GB/T1446.