Failure analysis of journal bearing used in turboset of a power plant

This paper presents a failure investigation on the damaged journal bearing, which supports the main-shaft of the Turboset of a power plant. The damage position is located at the hydrodynamic lubrication area of the bearing. A detailed fractographic and metallurgical investigation is conducted on the damaged lining layer of the bearing, which is made of tin-based Babbitt alloys, to analyze the damage mechanism and assess the possible reasons for this failure. The investigation results indicate that the main cause of the failure should be the direct contact and the rubbing between the shaft and the lining layer of the bearing at the damage position. Such contact and rubbing will cause local high temperature in the damage region and also cause the content decrease of the hard inclusion Cu6Sn5 on the Babbitt layer surface, and therefore deteriorate the mechanical performance of the Babbitt layer of the bearing and lead to the serious damage to the Babbitt layer eventually. By this research, some direct and valuable information is obtained for Babbitt lining layer design and operation condition optimization of bearings.