The results show that the sulphide inclusions in the steel are main reasons causing the worm fatigue fracture under cyclic stress.Proposals for selecting right materials are put forward.

• 结果表明,钢中硫化物类夹杂物是造成该电机蜗杆在周期应力作用下疲劳断裂的主要原因,同时提出了重新选材的建议。