The basic characteristics of the warm and hot sheet formings of high-strength steel are investigated experimentally and analytically. The amount of springback is markedly reduced when the temperature of the plastically deforming zone, or bending zone, is higher than 750K. It is found that this reduction of springback is caused by the partial ferrite recrystallization beyond this temperature, and it is confirmed by the quantitative measurements of the microstructure before and after sheet forming and elastic-plastic FEM. At present, it is commonly believed that the sheet should be heated up to the austenite temperature to suppress springback. From the results obtained by this investigation, we could conclude that what is important is to maintain the temperature of plastically deforming zone higher than the ferrite recrystallization temperature of the high-strength steel sheet at approximately 750K, to decrease springback after forming. This understanding is important in the design of the new processes of hot and warm sheet formings.
Springback of high-strength steel after hot and warm sheet formings
2005
4 Seiten, 10 Bilder, 2 Tabellen, 13 Quellen
Conference paper
English
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