| 摘要 |
<p>PURPOSE:To increase fatigue strength of a water turbine runner, by a method wherein, by using a steel ball with a specified diameter, a region having compression residual stress exceeding a polishing amount needed after shot peening machining is held. CONSTITUTION:By using a steel ball with a diameter of 4-10mm, shot peening machining is applied on the root part of a water turbine runner to form a deep surface layer with a size of maximan 4mm having compression residual stress. After removal of the uneven part of a surface and a change of properties layer, which are produced resulting from shot peening, a sufficient next surface is caused to remain, and fatigue strength of the root part of the water turbine runner is improved, and this increases fatigue strength of the water turbine runner about ten times.</p> |
