Transactions of Materials and Heat Treatment

Title：Tight radius bending characterization technology of high-strength automotive steel

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ClassificationCode：TG386

year,vol(issue):pagenumber：2025,50(8):82-89

Abstract：

The influence factors of tight radius bending angle were analyzed, selecting DP780 steel to analyze the influence laws of specimen width, test speed and test end condition, selecting DH780 steel to analyze the influence law of specimen machining method, and selecting QP980 steel was selected to analyze the influence laws of pre-strain direction and bending direction. The results show that with the increasing of the specimen width, the tight radius bending angle decreases gradually, when the specimen width increases to about 50 mm, the tight radius bending angle tends to be stable. When the test rate is less than 20 mm·min-1 or greater than 30 mm·min-1, the tight radius bending angle fluctuates greatly. The test end conditions with different load thresholds have an influence on the tight radius bending angle, and selecting the load threshold method specified in VDA 238-100—2017 as the test end condition is likely to lead to misjudgment. The values of the tight radius bending angle are scattered and low by the machining methods of laser cutting and shearing, and the results are not scattered and are relatively high by the machining methods of wire cutting and grinding after shearing. The pre-strain direction and bending direction have a certain influence on the tight radius bending angle. Considering the test results, it is recommended that the specimen width is 60 mm, the test rate is 20-30 mm·min-1, a 30% decrease in the peak load is used as the test end condition, and the wire cutting is used as the machining method. Then during the test, the pre-strain direction and bending direction should be indicated.

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作者简介：黄磊（1981-），男，硕士，正高级工程师 E-mail：12285269@qq.com 通信作者：苏洪英（1969-），女，硕士，正高级工程师 E-mail：13898019925@163.com

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