| Nowadays, due to their high strength, Advanced High Strength Steels (AHSS)are widely used in automobile industry for lighter automobile body. While AHSS havebig problem of springback, and there are setbacks for the both traditional methods ofsolving springback problem in practice. Recently it is found that electroplastic stressrelaxation functioned well in reducing bending springback. So it is meaningful toresearch on the changing law of the main factor, electroplastic relaxation, effecting thereduction of springback.In this paper, experiment and analysis were carried out to study electroplasticrelaxation and its application in bending springback reduction of DP980, The concretework includes:DP980was used in study. And firstly isothermal tensile was used to get theyoung’s module’s relationship with temperature. Electroplastic treatment experimentwas used to evaluate the workability of DP980subjected to electricity treatment.Used experiments to analyze the effect of pulse frequency and maximum currentdensity to electroplastic relaxation, and made temperature as the variable to measurethe electroplasticity in experiments. Special V shape bending mold was used to doelectroplastic relaxation reducing bending springback experiments.Concluded the result of the relaxation experiments, and built relaxation law mathmodel for DP980with ultimate original stress. Based on geometry similarity ofdifferent relaxation curve, a math model with multiplication of temperature functionand time function was proposed.Analyzed the result of springback reduction experiment, built bendingspringback calculating math model based on the effect of stress relaxation andmaterial softening, and the true strength of tensile strength point was selected as thebasis to evaluate material softening effect.Both models fitted well with experiments’ result, and they are meaningful todirect the application of electroplastic relaxation in springback reduction practice. |
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