Effects of Quenching and Tempering Treatment on the Microstructure and Mechanical Properties of Microalloyed High Strength Steel
The microstructure of the microalloyed high strength steel after different quenching and tempering process treatments is characterized by means of optical microscope,field emission scanning microscope and electron backscatter diffraction microscope.the effects of the process parameter differences on the microstructure and mechanical properties are studied.The results show that the microstructure of the test steel obtained after 905 ℃ quenching+635℃ tempering mainly consists of tempered martensite with higher strength achieved due to the fine sub-structure,small size precipitates in diffusion distribution and high proportion small angle grain boundary.The strength of the test steel a-chieved after 840 ℃ secondary quenching+635 ℃ tempering is decreased with improved plasticity and yield to tensile strength ratio due to increased soft phase ferrite content and reduced proportion of small angle grain boundary.When the tempering temperature increases to 655℃,the grains are coarsened the lattice distortion degree is reduced,the strength is decreased,while the plasticity is significantly reduced due to the element gathering,stress concentration at grain boundary,gathered and grown precipitates.
Quenching and temperingMicrostructureMechanical propertiesSmall angle grain boundary
万方数据
维普
