Materialization of the Heat-Affected Zone with Laser Tailor-Welded HPF 22MnB5 Steel Using FLD and the Fracture Displacement Method in FE Simulation

Abstract

Using a tailor-welded blank (TWB) and hot-press forming (HPF), a 22MnB5 blank was surface-treated under four conditions. The penetration rates of the FexAly compounds under the four surface-treatment conditions were investigated, and the hardness values were measured. A finite element (FE) simulation was performed for the characteristics of the heat-affected zone (HAZ), using the hardness value and results of previous researchers. In particular, the mechanical property settings of the mesh were designed to realize the conditions for the FexAly compounds in the HAZ. Fine meshing was performed by partitioning the HAZ sections. For the mechanical properties of the HAZ with the FexAly compounds, the strength was predicted from the hardness value, and the elongation values investigated by other researchers were used. The forming limit diagram, which was proportional to the elongation, was predicted. Specific elements were defined as the areas with FexAly compounds, which played the same role as impurities. Tensile TWB–HPF specimens with different HAZ characteristics under four surface-treatment conditions were fabricated. Experiments and FE simulations were performed and compared. Details are as follows: For loads, a minimum error rate of 3% and a maximum error rate of 6% were obtained. For displacement, a minimum error rate of 9% and a maximum error of 25% were obtained. The feasibility of the simulation was verified by comparing the simulation and experimental results. A match of more than 75% was obtained.

Keywords

• 22MnB5
• tailor-welded blank
• heat-affected zone
• hot-press forming
• Al–Si coating layer
• finite element method