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本文通过对冷拉Si-Cr气阀钢的断裂力学分析,将各种影响冷拉劈裂的因素归结为对钢的断裂韧度K_(Ic)、切向冷拉残余应力峰值σ_(tm)和表面缺陷深度α这三个方面。应用如下公式判断冷拉钢棒和钢丝是否可能发生冷拉劈裂破坏: K_(Ic)≈σ_(tm)((πα)~(1/2))(K_1/K_0) 冷变形后较精确的K_(Ic)值系由冷镦试样测得。据此制定了控制缺陷深度的冷拉工艺,使Si-Cr钢在室温能够经受的一次冷拉压缩率达20—30%或更高,大大超过了以往规定的压缩率限度,达到了热拉才能容许的压缩率,避免了劈裂和再结晶粗晶,取得了高产优质的效果。
Based on the fracture mechanics analysis of cold-drawn Si-Cr valve steel, the factors that affect the cold-drawing splitting are summarized as follows: the fracture toughness K Ic, the residual σ tm, And the surface defect depth α these three aspects. The following formula is used to determine whether the cold drawn steel bars and steel wires are likely to undergo cold drawing and splitting failure: K_ (Ic) ≈σ_ (tm) (πα) ~ (1/2)) (K_1 / K_0) K_ (Ic) value is measured by the cold heading sample. Accordingly, a cold-drawing process for controlling the depth of defects has been established so that the compressive rate of primary cold-drawn steel of Si-Cr steel can withstand 20-30% or more at room temperature, which greatly exceeds the compression rate limit previously stipulated, To allow the compression rate, to avoid the split and recrystallized coarse grain, and achieved high yield and quality results.