Warm Tension Flow Stress Model of DP Steel LTWB Based on KS Function

Abstract

For high strength LTWBs used widely in light-weigh auto body production, warm forming process has become an effective solution to improve their forming performance and reduce springback. While the flow-stress model of LTWB warm forming is vital to determine reasonable warm forming process scheme, and predict precisely LTWB forming status and springback. In the present work, aimed to 1mm thickness DP steel LTWB (B340/590DP), a warm tension flow-stress model is proposed based on KS function and bi-linear interpolation by analyzing characters of the stress-stain curve obtained from warm tension test. Via comparing the model prediction results with those of other existing flow-stress models and experiment data, it is verified that the proposed model can not only give more closely the stress-strain relationship than other models during uniform plastically deforming and plastic yielding, but also can indicate the occurrence of necking phenomenon.