316LN钢热成形过程损伤断裂模型与数值模拟

Modelling and simulation of 316LN steel damage and fracture during hot deformation

以核电用钢316LN为对象,研究其热成形过程中的开裂规律,以及变形开裂与温度、应变速率及应力三轴度等因素的关系;建立了高温状态下基于Bonora模型的损伤演化方程。进行了4种形状试样的镦粗实验,每种试样分别在20个不同压下率下进行镦粗,以获得开裂时的临界压下率。基于所建立的损伤演化方程,在与实验相同条件下应用MARC软件对变形中的开裂现象进行数值模拟,得到的开裂时压下率与实验测得的临界压下率基本一致,说明所建立的损伤演化方程能有效预测该材料的热成形开裂问题。

316LN steel is popular used in nuclear power generations .To study the fracture condition of steel in hot deformation , this paper took 316LN steel as an example and investigated the relationship of cracking in deformation with the working parame-ters such as temperature ,strain rate and stress triaxiality .A damage evolution model was established based on Bonora model for the condition of hot deformation .To verify the model ,four sets of upsetting experiments were conducted .Each set of experiment was conducted at 20 reduction rates to get the critical reductions at cracks ..Based on the model ,the numerical simulations for cracking phenomenon were carried out using FE software Marc under the same conditions as in experiments .The reductions at crack obtained by the simulation are generally close to the ones obtained by the experiments ,which demonstrated that the pro-posed damage and fracture model is capable to predict the crack problem for this material during hot forming .