Antifatigue mechanism of cold-extruded internal thread based on high-strength steel

作者：Miao Hong^*; Zuo Dun Wen; Zhang Rui Hong; Wang Min; Wang Shu Hong

来源：Journal of Functional Materials, 2011, 42(9): 1547-1550.

• Anti-fatigue
• Cold extrusion
• Dislocation densities
• Fatigue notch
• Fatigue properties
• Fibrous structures
• Forming process
• Hardened layers
• Internal threads
• Metal surfaces
• Microscopic viewpoint
• Normal direction
• Residual compressive stress
• Tooth surface

According to the forming process of cold-extruded internal thread of high-strength steel, the effect of parts status on the fatigue properties of internal thread was studied from the microscopic viewpoint, such as residual stress, surface roughness, microhardness, hardened layer, etc. The results showed that the metal surface of cold-extruded internal thread had a long fibrous structure, and it appeared to be streamline type and distributed along the normal direction of the tooth surface. The grains were pressed and refined, and the dislocation density was increased significantly. The work hardening phenomenon was appeared, and made the strength and the hardness of the metal increase. The residual compressive stress field formed on the surface of the metal could eliminate the impact of stress concentration, reducing fatigue notch sensitive, extending period of crack forming and slowing or restraining the expanding of the crack. The surface of cold-extruded internal thread had obvious finish mark, and its smooth of the surface was well. The surface roughness could be eliminated effectively, and reducing stress concentration and contributing to increasing the fatigue properties of internal thread.

• 出版日期2011
• 单位南京航空航天大学