Elastic modulus is one of the most crucial mechanical property parameters that affects the plastic forming quality of bent parts, especially for springback. Elastic modulus practically varies with plastic deformation, and its precise description is necessary to enhance simulation precision for tube bending and gain steady, high-precision bent components by actual bending. Using repeated loading-unloading tensile tests (RLUTTs), the variation of elastic modulus of high strength 21-6-9 stainless steel tube (21-6-9-HS tube) in terms of plastic strain has been obtained, which its decreases rapidly at the beginning, then decreases tardily and tends to be stable in the end with increasing the plastic strain. The variation can be expressed as a first order exponential decay function. By embedding the variation of elastic modulus with the plastic strain into ABAQUS software to simulate numerical control (NC) rotary draw bending of the 21-6-9-HS tube, the prediction precision for the springback angle, springback radius, maximum cross section distortion ratio and maximum wall thinning ratio can be improved by 11.98%, 7.62%, 35.53% and 11.55%, respectively.

弹性模量是影响弯曲零件塑性成形质量（尤其是回弹）的最关键的机械性能参数之一。弹性模量实际上随塑性变形而变化，因此必须对其进行精确描述，以提高管弯曲的模拟精度，并通过实际弯曲获得稳定，高精度的弯曲零件。使用反复的装卸拉伸试验（RLUTT），获得了高强度21-6-9不锈钢管（21-6-9-HS管）的弹性模量在塑性应变方面的变化，并迅速下降。刚开始时，随着塑料应变的增加，其起伏逐渐减小，最终趋于稳定。该变化可以表示为一阶指数衰减函数。