Cracking Cause Analysis of Valve Seat Laser Clad Layer

Author of the article:YANG Chengxin1 , ZHANG Xuliang1 , DU Zhijie2 , ZHANG Chunwan2 , WANG Pengcheng1

Author's Workplace：1. PetroChina Tarim Oilfield Company, Korla 841000, China; 2. Xi'an Maurer Petroleum Engineering Laboratory Co., Ltd., Xi'an 710065, China

Key Words：valve seat; cladding layer; columnar crystal

Abstract：A crack was found on the surface of the valve seat in the maintenance of an oil well. The cause of the cracking of the valve seat was analyzed with chemical composition test, mechanical performance test, macro/micro observation and other means. The results show that the structure of the cladding layer on the surface of the valve seat is columnar grain, and the crack propagation along the columnar grain is cleavage characteristic. The microstructure of other uncracked cladding layers is equiaxed crystal. Cracking of cladding layer on valve seat surface is mainly due to unreasonable cladding process, which produces a large number of columnar crystals, resulting in hard and brittle cladding layer, poor toughness, and cracking of cladding layer under vibration condition.