Abstract A series of dry finish-turning tests of a structural austempered ductile iron with PcBN cutting-inserts were run with a depth of cut of 200 μm, a feed-rate of 50 μm rev −1 and a cutting length of ∼100 m, and using machining speeds stretching from 50 to 800 m min −1 . Substructure developed within chips’ deformation zones was studied by transmission electron microscopy. At machining speeds equal or beyond 150 m min −1 , shear-induced unlocking of incomplete austempering transformation and continuous-cooling austempering of residual and retained austenite would plausibly stand as phase transformations behind the overwhelming volume fraction of ferrite within the chips’ deformation zones and related regions. Formation (and coalescence) of ferrite sub-grains within these zones, possibly concurrently with their parent shear-platelets, would be the result of rotational dynamic recrystallization. Substructure refinement in the deformation zones of chips formed under machining speeds equal or beyond 150 m min −1 could heighten the diffusion rates of cutting-insert components therein.

中文翻译：

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奥氏体球墨铸铁精车切屑变形区亚结构

摘要 对带有 PcBN 切削刀片的结构奥氏体球墨铸铁进行了一系列干式精车试验，切削深度为 200 μm，进给速率为 50 μm rev -1，切削长度约为 100 m，并使用从 50 到 800 m min -1 的加工速度。通过透射电子显微镜研究了在芯片变形区域内形成的亚结构。在等于或超过 150 m min -1 的加工速度下，残余奥氏体和残余奥氏体的不完全奥氏体转变和连续冷却奥氏体的剪切诱导解锁似乎是在切屑变形区内铁素体的压倒性体积分数和相关地区。在这些区域内形成（和聚结）铁素体亚晶粒，可能与它们的母剪切片同时发生，是旋转动态再结晶的结果。在加工速度等于或超过 150 m min -1 下形成的切屑变形区中的亚结构细化可以提高其中切削刀片部件的扩散速率。