Machining method for improving fatigue strength of non-quenched and tempered bolt

The invention belongs to the technical field of fastener manufacturing, and particularly relates to a machining method for improving the fatigue strength of a non-quenched and tempered bolt. The non-quenched and tempered bolt comprises the following main chemical components in percentage by weight: 0.08 to 0.13 percent of C, less than or equal to 0.30 percent of Si, 1.60 to 2.00 percent of Mn, 0.010 to 0.040 percent of Nb and 0.015 to 0.050 percent of V. A hot-rolled wire rod serves as a raw material, and the bolt is machined through the procedures of acid pickling, phosphorization, saponification, cold drawing, cold heading forming, stabilizing treatment, thread rolling, surface treatment and the like. According to the method, the technological process of bolt manufacturing is improved, stabilizing treatment is conducted firstly and then thread rolling is conducted after cold heading forming, meanwhile, the stabilizing treatment scheme is optimized, the hardness difference of different parts of the bolt is e