| The high-performance 05Si2 Cr Cu Ni soft magnetic steel studied in this paper is a newly developed steel for high-speed vacuum maglev trains in my country.It is connected to the bottom steel of the 20 Cr Mo train by welding,and relies on electromagnetic force to support,guide,traction and brake.In order to make the welded joint of 05Si2 Cr Cu Ni and 20 Cr Mo meet the performance requirements of maglev train operation,the welding and post-weld heat treatment process are particularly important.Therefore,the research on the welding process and post-weld heat treatment of 05Si2 Cr Cu Ni and 20 Cr Mo has important engineering significance.The main contents of this research include:1)The welding procedure qualification of 05Si2 Cr Cu Ni and 20 Cr Mo submerged arc welding joints was carried out,and a new welding plan was formulated according to the qualification results.2)The welding method of gas shielded welding is used to complete the welding test under different heat input.The performance of the welded joint is evaluated,and the residual stress of the welded test plate is detected by the X-ray diffraction method.3)Use Jmatpro simulation software to simulate and analyze the high temperature performance of 05Si2 Cr Cu Ni,20 Cr Mo and ER50-6 welding wire materials used in this thesis to solve the problem of non-linear changes in the physical properties of materials with temperature during the welding process.4)Based on the ABAQUS software,the temperature field and stress field model of05Si2 Cr Cu Ni and 20 Cr Mo multilayer multi-pass welding are established,and the welding process and post-weld temperature,residual stress and deformation are simulated and studied.5)Use better welding process parameters and different annealing temperatures for joint post-weld heat treatment tests.The effect of post-weld heat treatment on welded joints was studied by comparing the mechanical properties,microstructure and residual stress of the test plates.The test results show that the structure of 05Si2 Cr Cu Ni material is mainly ferrite,with coarse grains and low toughness.It should be normalized before welding test to improve its overall performance.When welding,the gas shielded welding method with small heat input and the appropriate preheating temperature can be used to significantly improve the comprehensive mechanical properties of the welded joint.The model stress value is compared with the experimental stress value.The results show that in the transverse direction of the weld,the transverse residual stress is compressive stress at the center of the weld and tensile stress near the heat-affected zone.It gradually decreases in the direction away from the weld,and tends to zero.The longitudinal residual stress is tensile stress near the weld and the heat-affected zone.In the direction away from the weld,the longitudinal residual stress gradually decreases;in the longitudinal direction of the weld,the transverse residual stress and the longitudinal residual stress are tensile stresses,basically at stable state.The stress distribution law obtained by the simulation is similar to the actual measurement result,which verifies the reliability of the modeling process and analysis method. |
