| The requirement of vehicle lightweight has become the main development trend in the field of automobile manufacturing,which improves the overall strength and safety of the vehicle and reduces the weight of the vehicle at the same time.The hot stamping technology of high strength steel can greatly improve the strength of automobile components and reduce the weight of components,and is widely used in the production and manufacturing of automobile components.But higher strength does not guarantee higher vehicle safety,such as B-pillar.Proper control of mechanical properties distribution is required so that the combination of "soft"(low strength area)and "hard"(high strength area)of hot stamping parts can ensure good vehicle safety.The hot stamping forming process of22 Mn B5 high-strength steel-Q235 steel tailored weld plate was studied by thermal simulation test,finite element simulation and hot-pressing test verification.The thermal tensile tests of 22 Mn B5 high-strength steel and Q235 steel were carried out by thermal simulation tester,and the stress-strain curves of the two base materials at different temperatures were obtained.Quantitative thermal tensile deformation test of 22 Mn B5 high-strength steel-Q235 steel tailored welded plate was completed.The flow stress curves at different temperatures in the weld zone were obtained by combining numerical simulation analysis,thermal tensile deformation of tailor-welded plate and hot stamping test of tailor-welded plate.It lays a foundation for building finite element numerical model of tailor-welded blank hot stamping forming.A thermo-mechanical coupled finite element numerical model for the deformation process of U-shaped 22 Mn B5 high-strength steel-Q235 steel tailored weld plate during hot stamping was established by dealing with boundary conditions and contacts.The influence of process parameters on forming process of tailor-welded blank hot stamping is analyzed,and the influence rules of process parameters on forming quality are summarized.The cooling and quenching process after hot stamping of tailored weld plate directly determines the mechanical properties of hot stamped parts of tailored weld plate.To accurately predict the quenching effect of process parameters.A thermodynamic-fluid-solid coupling finite element numerical model of 22 Mn B5 high-strength steel-Q235 steel tailored weld plate duringhot stamping deformation holding pressure quenching cooling process was established.The influences of water flow rate,cooling time and forming temperature on cooling effect are analyzed and the influencing rules are summarized.It provides technical support for the research on hot stamping forming process test of 22 Mn B5 high-strength steel-Q235 steel tailored weld plate.An experimental platform for hot stamping forming of 22 Mn B5high-strength steel-Q235 steel tailored weld plate was established.The hot stamping forming test of U-shaped 22 Mn B5 high-strength steel-Q235 steel tailored weld plate was completed by combining the simulated process parameters.The influence mechanism of process parameters on hot stamping of tailor-welded blanks was studied from three aspects: dimensional accuracy,microstructure and mechanical properties of hot-pressed parts.It can be seen from the research results that a lot of marten site structure occurs in the high-strength steel zone of 22 Mn B5 high-strength steel tailored weld plate.The tensile strength is over 1400 MPa and the elongation is about 8%.The tensile strength of Q235 steel zone is about 380 MPa and the elongation is about 26%.The tensile strength and elongation in the weld zone are between the two,which satisfies the requirement of mechanical property distribution of the formed part very well. |
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