Raw material defects. The steel contains severe non-metallic inclusions, shrinkage cavities, or has a substandard chemical composition. For example, abnormally high nitrogen content (exceeding 0.017%) significantly increases aging sensitivity and brittleness, or excessive arsenic content leads to elemental segregation at grain boundaries, causing cold brittleness.

Inappropriate hardness matching. If the original hardness of the 45# round bar is too high (e.g., without annealing, hardness far exceeds 229HB) and its plasticity is poor, the material cannot withstand the enormous tensile stress during large diameter reduction processing using cold-drawing dies, resulting in brittle fracture.

Time：21/05/2026 16:38:26

Answers

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