Effect of Cell Boundary Inclusions on QT400-18L Properties
Author of the article:DENG Han;CHEN Lu;ZHU Guihua
Author's Workplace：CRCC Qishuyan locomotive&Rolling Stock Technology Research Institute Co.,Ltd.,Changzhou 213011,China
Key Words：low temperature ductile iron inclusions fine grain strengthening
Abstract：
This paper studies the microscopic mechanism of low temperature impact toughness reduction caused by grain boundary inclusions,and heat treatment technology is adopted to reduce grain boundary segregation and improve grain size grade,thus improving low temperature impact toughness and tensile strength of materials.The research shows that the inclusions accumulated at the grain boundary are carbide and oxide,which greatly reduce the tensile strength and impact toughness of the material.Conventional high-temperature graphitization annealing cannot improve its low-temperature impact toughness.Through fine grain strengthening heat treatment technology,the grain size is improved from 30 um^40 um to 15 um^25 um,the tensile strength is improved from 383 MPa to 418 MPa,and the low temperature impact toughness at-40℃is improved from 7 J to more than 14 J.
