Editorial Department of Advances in Aeronautical Science and Engineering
Doi
Abstract
In order to meet the reliability of an aero-engine and ensure the flight safety of helicopter, the welding repair of the crack fault of the Ⅳ-stage guide vanes is studied. The cracks are observed by scanning electron microscopy and optical microscopy to analyze the root causes of guide vanes failure. The high temperature box furnace is used to conduct properties recovery heat treatment of Ⅳ-stage guide vanes. The cracks are repaired by TIG（Tungsten Inert Gas）welding. The microstructure, hardness, high temperature strength and thermal shock performance before and after repair are compared and evaluated. The repaired Ⅳ -stage guide vanes are installed on the engine for test verification. The results show that a large amount of σ phase is generated at grain boundary during service, decreases the strength of grain boundary, and finally corrosion cracks are generated. Properties recovery heat treatment can lower the brittleness and improve the weldability of matrix materials. The welded joint of Ⅳ -stage guide vanes produced by TIG welding meets the standard requirements. The dimensions of Ⅳ -stage guide vanes, on which property recovery heat treatment, TIG welding and stabilization treatment are conducted, meet the requirements of engine assembly. No cracks, spalling or other abnormalities are detected after engine test
