Abstract
DEFORM software was used to simulate the forming process of stainless steel high-lock nuts with zero-allowance. The actual test sample was prepared through the forming process and the microstructure of the sample was observed with scanning electron microscope (SEM). Simulation results show the forming process of the nut consists of three stages: upsetting, flange forming, and hexagonal forming. The staging was based on the analysis of the stress distribution and the metal flow diagram during the simulation process. During the forming process, the metal mainly flows along the direction of the least resistance; microstructure analysis of the test sample shows that the streamline characteristics of the flange part are distinct. The metal tends to flow downwards after being extruded at the top. The resistance of the hexagonal part is the largest, resulting in a fine grain streamline at the inner and outer surfaces of the hexagonal part. The results of the actual sample forging and the simulation are consistent.