How does low or high ST13 steel plate hardness affect stamping?
Both high and low ST13 steel plate hardness can significantly impact stamping performance, primarily in terms of forming performance, mold wear, and product quality:
1. Impact of High Hardness
Increased Forming Difficulty: Higher hardness means decreased material plasticity and increased yield strength, requiring greater forming force to achieve plastic deformation during stamping. Parts with complex shapes (such as deep drawing and multiple bending passes) are prone to localized stress concentration, leading to cracking, wrinkling, or scratches. Defects are particularly prone to developing at sharp corners and deep cavities.
Increased Mold Wear: High material hardness increases friction and impact forces on the mold, accelerating wear on the mold cutting edges and forming surfaces, shortening mold life, and potentially causing mold deformation due to excessive force, affecting the precision of subsequent products. Significant springback: Materials with higher hardness experience more pronounced elastic recovery (springback) after stamping, leading to deviations in part dimensional accuracy. In particular, the angles and curvatures of bent parts can easily exceed design requirements, requiring additional process parameter adjustments (such as adding a correction step) to compensate.
2. Impact of Low Hardness
Insufficient Material Strength: Low hardness may also be accompanied by excessively low yield strength, making the material prone to excessive deformation or "collapse" during stamping. This is particularly true during the stretching process, where insufficient tension may cause wavy wrinkles at the edges of the blank, or excessive local thinning may lead to scrapping of the workpiece.
Surface Quality Issues: Materials with too low hardness are prone to scratches and indentations due to friction on the surface in contact with the die during stamping, or localized accumulation due to excessive material fluidity, affecting the product's appearance.
Poor Dimensional Stability: Due to insufficient material strength, the formed part may experience secondary deformation due to external forces during subsequent processes (such as welding and assembly), making it difficult to ensure the dimensional accuracy of the final product. Summary: ST13, as a specialized stamping steel, is designed with a hardness within the optimal range of 50-70 HRB to achieve a balance between ductility and strength. Hardness that is too high or too low disrupts this balance, increasing processing difficulty and scrap rates. Therefore, in actual production, the hardness must be strictly controlled within the standard range to ensure stability in the stamping process and product quality.