Effect of Microstructure on mechanical and Charpy impact properties offerrite-martensite dual phase API X52 pipeline Steel

Authors : Belkacem BOUTESSOUNA

Pages : 33-36

View : 13 | Download : 9

Publication Date : 2017-11-01

Article Type : Research Paper

Abstract :The microstructural changes that occur during intercritical annealing treatment at 780°C of API X52 steel have been investigated. Three treatments were developed to produce dual phase insert ignore into journalissuearticles values(DP); microstructure: Intermediate Quenching Treatment/Air insert ignore into journalissuearticles values(IQ/A);, Intermediate Quenching Treatment/Water insert ignore into journalissuearticles values(IQ/W); and Step Quenching Treatment insert ignore into journalissuearticles values(SQ);. The IQ/W resulted in the formation of fine and fibrous martensite morphology uniformly distributed in the ferrite matrix. However, the IQ/A treatment showed a spherical network of martensite along the ferrite/ferrite grain boundaries. The SQ yielded blockly and banded martensite and ferrite morphology. The experimental results show that API X52 insert ignore into journalissuearticles values(DP); steel with finely dispersed microstructures insert ignore into journalissuearticles values(IQ/W); have higher Charpy impact properties and lower ductile–brittle transition temperature insert ignore into journalissuearticles values(DBTT); than insert ignore into journalissuearticles values(DP); steel with banded microstructures. A carefully conducted comparison of fracture surfaces of the representative specimens obtained after IQ and SQ treatments has been studied.
Keywords : Intercritical annealing, Dual phase steel