The tempering behavior was experimentally studied in lath martensitic wear-resistant steels with various Mo/Ni contents after tempering at different temperatures from 200to 600℃.It is shown that a good combination of...The tempering behavior was experimentally studied in lath martensitic wear-resistant steels with various Mo/Ni contents after tempering at different temperatures from 200to 600℃.It is shown that a good combination of hardness（HV）（420-450）and-20℃impact toughness（38-70J）can be obtained after quenching and tempering at 200-250 ℃.The microstructure at this temperature is lath structure with rod-like and/or flake-likeε-carbide with about 10nm in width and 100nm in length in the matrix,and the fracture mechanism is quasi-cleavage fracture combining with ductile fracture.Tempering at temperature from 300to 400℃results in the primary quasi-cleavagefracture due to the carbide transformation from resolved retained austenite and impurity segregation between laths or blocks.However,when the tempering temperature is higher than 500℃,the hardness（HV）is lower than 330 and the fracture mechanism changes to ductile fracture due to the spheroidization and coarsening of cementite.Additions of Mo and Ni have no significant effects on the carbides morphologies at low tempering temperatures,but improve the resistance to softening and embrittling for steels when tempered at above 350℃.展开更多
基金Sponsored by National Basic Research Program(973Program)of China(2010CB630800)
文摘The tempering behavior was experimentally studied in lath martensitic wear-resistant steels with various Mo/Ni contents after tempering at different temperatures from 200to 600℃.It is shown that a good combination of hardness（HV）（420-450）and-20℃impact toughness（38-70J）can be obtained after quenching and tempering at 200-250 ℃.The microstructure at this temperature is lath structure with rod-like and/or flake-likeε-carbide with about 10nm in width and 100nm in length in the matrix,and the fracture mechanism is quasi-cleavage fracture combining with ductile fracture.Tempering at temperature from 300to 400℃results in the primary quasi-cleavagefracture due to the carbide transformation from resolved retained austenite and impurity segregation between laths or blocks.However,when the tempering temperature is higher than 500℃,the hardness（HV）is lower than 330 and the fracture mechanism changes to ductile fracture due to the spheroidization and coarsening of cementite.Additions of Mo and Ni have no significant effects on the carbides morphologies at low tempering temperatures,but improve the resistance to softening and embrittling for steels when tempered at above 350℃.
