Cold stamping performance for complex components of ultra-high strength steel QP1180
For QP1180 steel automobile B-pillar,its cold stamping performance was investigated by finite element simulation,stamping experiments,scanning electron microscopy and other methods.The simulation results indicate that the maximum thinning rate of main parts for the part is 12.7%under the blank holder force of 1400 kN,the friction coefficient of 0.17 and the stamping rate of 500 mm·s-1,with good formability.The experimental results show that the cold stamping parts have no wrinkling or cracking defects,and the surface forming quality is excellent.After forming,the tensile strength at position D of the part reaches 1343 MPa,with an elongation of 24.5%and a strong plastic product of 32.9 GPa·%,demonstrating a high capacity of strain-induced reinforcement.At position E,the strong plastic product reaches 30.2 GPa·%,while at position F,the tensile strength reaches 1454 MPa and the strong plastic product is 22.1 GPa·%.The micro-hardness at three positions reaches 410 HV.In the area with larger deformation of part,the residual austenite content at position F is significantly lower than that at position D,and the martensite content is higher.The fracture morphologies in three positions belong to the ductile fracture,with large and deep dimples at position D,indicating good plasticity.The size of dimple at position E decreases,and the depth of dimple becomes shallower.At position F,there are obvious tearing edges and a decrease in material plasticity.
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