Analysis And Countermeasure On Defects Of Key Transmission Components Used In Wind Power Equipment

This paper mainly presents a failure analysis on three kinds of key transmission components (including yaw gear-ring, secondary sun-gears and third output-gears), which cracked in service or fabricating process. The macrostructure and microstructure of failed components were observed analyzed by optical microscope (OPM) and scanning electron microscopy (SEM). Chemical composition of matrix materials and microcomposition on the fracture surfaces and matrix materials were analyzed by emission spectroscopy (OES) and X-ray energy dispersive spectroscopy (EDX). The present phases were determined using X-ray diffraction (XRD). Macro and micro fractographic features were investigated visually and SEM to determine the failure mechanism and failure causes. Combined with the hear treatment tests in site, the improvements were proposed to prevent from the similar failure in future. The main results can be concluded as follows:(1) In the process of mid-frequency quenching, the steels with medium hardenability, such as40Cr steel, are extremely sensitive to using temperature range of new-type water-soluble quenching agent (F2000) based on organic polymers, and is easily induced cracking during quenching beyond the suitable temperature range. Control the temperature of quenching medium and monitor its concentration regularly to avoid similar cracking failure.(2) Crack failure of sun-gears is closely presence of calcium aluminate in raw materials. A new technology was conducted on the larger sun-gear:once quenching after carburizing, followed by spheroidizing annealing, to decrease tensile stress on the subsurface, which can be prevent from cracking of the large sun-gear even if poor metallurgical quality is not changed.(3) Insufficient holding time during secondary quenching carburized gear can lead to low surface hardness and core hardness of carburized gear so as to bring about faulty carburized gear. Occurrence of the defect on the carburized gear can be avoided by improving secondary quenching technology and optimizing related parameters.(4) The main factors which is related to the service properties of three kind of transmission were determined by detailed investigation on the failed components and heat treatment tests, including metallurgical quality of raw material, heat treatment technology and its operating. Some improvements have been proposed to raise the service properties of transmission components used in wind power equipment.