Surface Defects on Forged Nut of Stainless Steel
1 Dept. of Mechanical Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan
2 Ihara Science Corporation, Ihara Takanawa Building, 3-11-3 Takanawa Minato-ku, Tokyo, 108-0074 Japan
Surface quality of nuts used in gas pipe joints is an important issue because the surface state affects the fatigue characteristics. Surface defects of nuts produced by warm forging from a stainless steel are observed and the cause of defect generation is discussed based on the numerical results of FEM simulation. It is revealed that there exists the lap defect on the drawn wire surface with an opened end and the surface defects on the forged nut are generated by the tensile stress during forging since there exists a moment at almost the whole area of the billet surface that a tensile stress over 200MPa is generated during nut forging.
© Owned by the authors, published by EDP Sciences, 2016
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