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DP1000 steel sheets with different surface treatments are taken to three‐point bending tests to evaluate their damage and fracture behavior. It is found that different surface treatments yield different fracture behaviors. Conventional finite‐element (FE) simulation with an uncoupled material model is able to capture the material's response only for the sheets with the perfectly smooth surface condition. A multiscale strategy is introduced to quantitatively include the surface information into the material model. The localization at the microlevel simulation allows adjusting the fracture criterion of the surface elements in the macrolevel simulation. Therefore, a good agreement between FE simulation and experiment is yielded.

Experimental and numerical investigations on the description of cold formability of extra abrasion-resistant steel considering surface roughness effects were performed in this study. A novel multiscale numerical approach to quantitatively evaluate the impacts of surface roughness on the cold formability/bendability of heavy plates was proposed and verified. The macroscopic ductile damage behavior of the investigated steel was described by a hybrid damage mechanics model, whose parameters were calibrated by notched round-bar (NRB) tensile tests and single-edge notched bending (SENB) tests. The surface roughness was characterized by confocal microscopy and statistically incorporated into a two-dimensional representative volume element (RVE) model. For the assessment of the bendability of heavy plates in the component level, the critical ratio between the punch radius and the sample thickness r/t in three-point bending tests was predicted and compared with experimental results. After the surface roughness effects were taken into consideration, a significant improvement in the predicted results was achieved. A good match between the simulation and experimental results confirmed the indispensable influences of surface roughness on the bendability of steels and validated the efficiency of the multiscale simulation approach in the quantitative description of surface roughness affected ductile damage evolutions.

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