Abstract: The reasons for the total decarbonization failure of 30CrMnSiNi2A cold drawing hexagonal steel are analyzed， the results show that when the deformation amount of cold drawing is in the critical deformation range， the grains in the cold deformation area are coarse after annealing at 690 ℃， which affects the determination of total decarbonization. The recrystallized grains in the cold deformation zone area are refined after heat treatment when the single drawing deformation is between 21% and 30%. Therefore the accuracy of total decarbonization determination is eliminated because the deformation is in the critical deformation interval and the grain is coarse after drawing annealing.Through the production practice， the single deformation of cold drawing is controlled in the range of 20%-25%， and reduce annealing temperature to 630 ℃， the total decarbonization of S22 mm cold drawing rolled reaches the standard requirements， and the decarbonization improvement effect is obvious.

Key words: 30CrMnSiNi2A Steel, Cold Drawing Hexagonal Steel, Recrystallization, Grain, Total Decarbonization, Heat Treatment, Ferrite

摘要： 分析30CrMnSiNi2A钢冷拔六角材总脱碳不合原因，结果表明：当冷拔一次拔制变形量处于临界变形区间时，经690 ℃退火后冷变形区域晶粒较为粗大，影响总脱碳判定。当冷拔一次拔制变形量在21%～30%时，经热处理后冷变形区域再结晶晶粒得到细化。从而消除因变形量处于临界变形区间导致拔制退火后晶粒粗大而影响总脱碳判定准确性。通过生产实践将冷拔一次变形量控制在20%～25%，并降低退火温度到630 ℃，生产的S22 mm六角材总脱碳满足标准要求，且脱碳层改善效果明显。

关键词: 30CrMnSiNi2A钢, 冷拔六角材, 再结晶, 晶粒, 总脱碳, 热处理, 铁素体