Failure mode and mechanism of a blast furnace tuyere

• The high temperature at the front end of the tuyere resulted in grain growth and reduced hardness. • The perforation failure at the front end was a result of gyratory coke scraping in the blast furnace. • Cracks in the coating of the inner wall were generated due to the uneven composition distribution. • The wear mechanism of the inner wall of the tuyere was different at different positions. • the wear faiure models of the tuyere were established for the first time. In this study, the failure modes of a blast furnace tuyere after service damage were systematically investigated. The high ambient temperature caused grain growth and hardness reduction at the front end of the tuyere. Owing to scraping by gyratory coke in the blast furnace, a perforation formed at the front end of the tuyere, causing damage. Owing to the uneven distribution of components caused by repair welding, cracks occurred in the front coating of the inner wall of the tuyere. The wear of the inner wall of the tuyere was related to the angle and depth of the coal injection gun, and the wear mechanism differed at different positions. Thus, tuyere failure is mainly attributed to the wear of the front end and inner wall. Therefore, it is necessary to develop a coating with excellent high-temperature wear resistance to protect the inner wall and the front end of tuyeres, thereby extending their service life.