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我厂生产的9CrSi 钢20×60×1050mm剪刀片,要求硬度为 HRC57～60,弯曲变形≤0.35mm,由于淬火后变形,所以必须校直。以前采用校直方法,即淬火时油冷至200～250℃左右,或在240～260℃硝盐中分级冷却。此时工件温度较高,尚存在大量过冷奥氏体,利用其良好的塑性进行校直。但淬火弯曲变形通常达2mm,校直过程中,随着温度的不断下降,马氏体转变量不断增多,在温度较低时就难以校直,甚至被压断。
I produced 9CrSi steel 20 × 60 × 1050mm scissors, requiring hardness HRC57 ~ 60, bending deformation ≤ 0.35mm, due to deformation after quenching, it must be straightened. Before the use of straightening methods, that is, quenching oil cooling to about 200 ~ 250 ℃, or 240 ~ 260 ℃ nitrate cooling grading. At this time the workpiece temperature is high, there are still a large number of supercooled austenite, the use of its good plastic straightening. But the quenching bending deformation is usually up to 2mm, straightening process, as the temperature continues to decline, increasing the amount of martensite transformation, the temperature is low, it is difficult to straighten, and even crushed.