Theoretical and Experimental Forming Limit Evaluation of High-Strength Steels up to 1500 MPa

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The prediction of sheet failure remains a highly relevant topic in metal forming research, particularly in relation to the experimental and theoretical determination of forming limit curves (FLCs). While the experimental construction of FLCs is a well-established but time-consuming process, theoretical and numerical approaches provide a more efficient alternative. However, their accuracy must be critically assessed, all the time. In this work, the formability of steel sheet with tensile strengths of 1500 MPa is investigated by combining experimental Nakajima tests with theoretical predictions of FLCs. Previous studies, such as models by Abspoel, Swift, Hill etc. have not addressed such high strength levels, where the diffuse and local neck points are quite close, leaving open the question of whether existing approaches remain valid for these materials. To provide a reference baseline, additional tests and calculations were also performed on lower-strength steel sheet (DP800). Our results show that the FLC points can be well estimated by two different theories in the positive quadrant, but there are noticeable differences between the measured and calculated values close to the plane strain point.

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Solid State Phenomena (Volume 388)

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57-66

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April 2026

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