Effect of Static Load Level of Ultrasonic Nanocrystal Surface Modification Technology on Fatigue Characteristics of SKD61 |
Suh Chang-Min,Kim Sung-Hwan |
Department of Mechanical Engineering Graduate School Kyungpook National University,Department of Mechanical Engineering Graduate School Kyungpook National University |
초음파 나노 표면개질 기술의 정하중 레벨이 SKD61 강의 피로특성에 미치는 영향 |
서창민,김성환 |
경북대학교 기계공학부,경북대학교 기계공학부 |
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© 2008 The Korean Society of Ocean Engineers
Open access / Under a Creative Commons License
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Keywords:
Ultrasonic nanocrystal surface modification(UNSM), Fatigue, Fish eye crack, Compressive residual stress |
핵심용어:
초음파 나노 표면개질, 피로, 어안균열, 압축 잔류응력 |
Abstract |
Ultrasonic nanocrystal surface modification (UNSM) is a method to induce severe plastic deformation to a material surface, so that the structure of the material surface becomes a nanocrystal structure from the surface to a certain depth. It improves the mechanical properties, namely hardness, compressive residual stress, and fatigue characteristics. Specimens of SKD61 were tested to verify the effects of the variation of UNSM static load level on fatigue characteristics. The results were as follows: the grain size of SKD61 treated with UNSM became very fine from the material surface to a $100{mu}m$ depth. The surface hardness of SKD61 was increased up to 37% after UNSM. And fatigue strength at $10^7$ cycles was increased by 8.3, 11.2, and 17.9% respectively, when the static load levels of UNSM were 4, 6, 8 kgf. |
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