Hightemperature strength of L245MB slab and elastic #br# properties of iron matrix
AI Songyuan1,2,LONG Mujun1,2,ZHANG Mengyuan1,2,CHEN Dengfu1,2, LIU Peng1,2,DONG Zhihua3
(1. College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China;
2. Chongqing Key Laboratory of VanadiumTitanium Metallurgy and New Materials, Chongqing
University, Chongqing 400030, China;3. Department of Materials Science and
Engineering, KTHRoyal of Technology, Stockholm, SE, 10044, Sweden)
Abstract: It′s important to understand the evolution of hightemperature properties of slabs from the microscopic structure and the macroscopic structure, which is of great significance to the performance and quality control of slabs. The variation of the hightemperature strength of the L245MB slab with the temperature was measured by the hot tensile test technique with the Gleeble system. For the Fe matrix phase, which was under different crystal structures and magnetic states, the EMTO firstprinciples method was used to calculate the bulk modulus B, the singlecrystal elastic constants c′ and c44, the polymorphic Young's modulus E, and the evolution of the system magnetic moment μ with temperature. The results showed that the cooling rate had little effect on the hightemperature strength evolution of the slab. The hightemperature strength took a transition near Ae3 and TC temperature, with a "platform" presented, where the average evolution rate of tensile strength was 0.008 MPa/℃ and the yield strength was 0.076 MPa/℃. The thermoplasticity of the slab had a different degree of decline in the temperature range of TC~Ae3, and the reduction of the area was the smallest at about 800℃, which was 59.02%~62.79%. The temperature range of ductility trough increased with the cooling rate increasing, and the surface temperature of the straightening zone should be controlled above 850 ℃ to avoid the crack generation. The elastic properties of the Fe matrix phase changed with the change of the magnetic state and the crystal structure. The transformation of the magnetic state had a greater influence on c′, c44, E, and the transformation of the crystal structure had a greater influence on B. During the transformation of FM to PM, c′ and E decreased by 64.09% and 10.33%, c44 increased by 57.82%, and B decreased by 34.38% with the change of bcc to fcc structure. The relationship between the evolution of single crystal elastic constant c′, polycrystalline Young's modulus E and the hightemperature strength of the slab were analyzed. It provides an idea for analyzing the macroscopic performance of the slab from the microstructural parameters of the crystal structure, which is a basis for the research and application of the first principles method in the hightemperature mechanical properties of steel materials.
艾松元,龙木军,张梦远,陈登福,刘鹏,董志华. L245MB钢铸坯高温强度与弹性性能研究[J]. 钢铁, 2019, 54(8): 194-201.
AI Songyuan, LONG Mujun, ZHANG Mengyuan, CHEN Dengfu,. Hightemperature strength of L245MB slab and elastic #br# properties of iron matrix. Iron and Steel, 2019, 54(8): 194-201.