Research on Metal Flow of Large Diameter Internal Thread during Cold Extrusion for Q460 High Strength Steel

摘要

According to the forming process of cold extruded internal thread for aircraft landing gear, the microhardness and the mechanical properties in the surface layer of cold extruded internal thread after heat treatment were investigated. The results showed that in comparison to the cold extruded internal thread without heat treatment, the microhardness and the tensile strength of crest, flank and root of the cold extruded thread after heat treatment were improved evidently. Its sustained maximum pulling force reached to 202.68KN, and it increased 9.24%. And the changes of its microhardness along the depth of the tooth were the same as the cold extruded internal thread without heat treatment, but its hardness depth decreased a little and the change gradient of the microhardness curve was lower.