Thread Content
When heat treatment is required during the manufacturing process to restore or improve the mechanical properties of the material, heat-treated test specimens of the base material should be prepared. When preparing the base metal heat treatment specimens, if it is also necessary to prepare the product welding specimens, it is permissible to prepare both types of specimens together. Mother metal heat treatment specimens shall be prepared if either of the following conditions is met: a) When it is required that the material be in the same heat treatment state as at the time of delivery, and if the heat treatment state at the time of delivery has been altered during manufacturing, reheat treatment is necessary ； b) During the manufacturing process, heat treatment is required to improve the mechanical properties of the material ； c) Compression members formed by cold forming or warm forming, which require heat treatment to restore the material properties after forming. The base metal heat treatment specimens shall be heat-treated in the same furnace as the base metal ； When it is not possible to heat treat in the same furnace, the same heat treatment condition as the base material should be simulated. As required by the design documents, where the studs are to undergo mechanical property tests after heat treatment, heat-treated test specimens shall be prepared in batches for inspection and evaluation. Each batch refers to bolts of the same type that are fed in simultaneously, having the same steel grade, the same furnace number, the same cross-sectional dimensions, and the same manufacturing process