High-temperature flow behavior and critical conditions of dynamic recrystallization of B55SiCr steel
B55SiCr steel is mainly used to make automobile suspension springs,valve spring steel wires,etc.It plays a pivotal role in the stability and safety of automobiles,and has high requirements for organizational performance.Taking B55SiCr steel as the research object,thermal compression experiments were carried out in the range of defor-mation temperature and strain rate of 800-1 050℃and 0.1-20 s-1,and based on the Zener-Hollomon parameters,a linear fitting method was used to construct a double Curved sine Arrhenius constitutive model.It is found that the flow stress of B55SiCr steel decreases with the increase of deformation temperature and increases with the increase of strain rate,and its thermal deformation activation energy(Q)is about 317 kJ/mol.The linear correlation coefficient(R)and the average absolute relative error(|(δˉ)|)of the flow stress prediction results and the test results obtained through the constitutive model are 0.992 15 and 3.70%,respectively.The work hardening rate curve was plotted.According to the stress-strain curve and the work hardening rate curve,the critical stress and strain for dynamic recrystallization(DRX)of B55SiCr steel were determined,and the critical condition and Z parameters are all in an exponential relationship.The microstructure of B55SiCr steel was analyzed,and it was found that under the condi-tion of low temperature thermal deformation,mixed crystal structure appeared,and the microstructure was in a non-uniform state,and under the condition of high temperature thermal deformation,the microstructure was uniform equiaxed crystal;the KAM diagrams and local orientation difference distribution diagrams under different deforma-tion conditions were drawn respectively.It was found that with the decrease of strain rate and the increase of defor-mation temperature,the dislocation density significantly decreased,the DRX became more complete and the grains gradually coarsened.The deformation conditions The HAGBs content at 1 050℃/0.1 s-1 increased by 13.51%compared with 850℃/10 s-1.At 1 050℃/0.1 s-1,the material is completely recrystallized and the grains are coars-ened.Under this deformation condition,B55SiCr steel has good hot workability;as the strain rate increases,the grains become refined.
NETL
NSTL
万方数据
