The brittle–ductile transition (BDT) widely exists in the manufacturing with extremely small deformation scale, thermally assisted machining, and high-speed machining. This paper reviews the BDT in extreme manufacturing. The factors affecting the BDT in extreme manufacturing are analyzed, including the deformation scale and deformation temperature induced brittle-to-ductile transition, and the reverse transition induced by grain size and strain rate. A discussion is arranged to explore the mechanisms of BDT and how to improve the machinability based on the BDT. It is proposed that the mutual transition between brittleness and ductility results from the competition between the occurrence of plastic deformation and the propagation of cracks. The brittleness or ductility of machined material should benefit a specific manufacturing process, which can be regulated by the deformation scale, deformation temperature and machining speed.

脆性-延性转变（BDT）在制造中广泛存在，具有极小的变形规模，热辅助加工和高速加工。本文回顾了极端制造中的BDT。分析了在极端制造中影响BDT的因素，包括变形尺度和变形温度引起的脆性-延性转变，以及晶粒尺寸和应变率引起的反向转变。安排了讨论以探讨BDT的机理以及如何基于BDT改善可切削性。提出脆性和延性之间的相互过渡是由于塑性变形的发生与裂纹的扩展之间的竞争而引起的。加工材料的脆性或延展性应有利于特定的制造工艺，