A three high planetary mill is used to produce bismuth-containing stainless-steel bars with high production efficiency. However, due to the influence of bismuth metal properties, the selection of processing parameters must be optimized to avoid the generation of cracking in the bar core. To solve this contradiction and find a suitable processing zone, the thermal simulation experiment of bismuth-containing stainless-steel material was carried out first to determine the constitutive relationship of the material. Three-roll planetary rolling experiments were carried out to determine the crack-producing region. Based on the Brozzo ductile fracture criterion, the fracture threshold of bismuth-containing austenitic stainless-steel bars in three-roll planetary rolling was determined by the finite element (FE) simulation. Five key process parameters were selected, with five factors and four levels of the orthogonal test designed. Through FE simulations, the possibility of cracking of stainless-steel bars with bismuth austenites in different technologic conditions was judged, and a set of optimal technologic parameters was obtained. Based on range analysis, the influence of various process parameters on bar cracking was discussed. Then, based on the dynamic material model and Murty criterion, the processing map of free-cutting austenitic stainless containing bismuth was established. It was found that the optimum process parameters were consistent with the processable range of the hot-working chart. Finally, the field rolling was carried out with the optimum process parameters, showing that there was no crack in the bar.

中文翻译：

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不锈钢易切削棒材成形裂纹的预测与预防

采用三高行星磨生产含铋不锈钢棒材，生产效率高。但由于铋金属性能的影响，必须优化工艺参数的选择，避免棒芯开裂的产生。为解决这一矛盾，寻找合适的加工区，首先进行了含铋不锈钢材料的热模拟实验，确定了材料的本构关系。进行了三辊行星轧制实验以确定裂纹产生区域。基于Brozzo延性断裂准则，通过有限元（FE）模拟确定含铋奥氏体不锈钢棒材在三辊行星轧制中的断裂阈值。选择了五个关键工艺参数，设计了五个因素和四个水平的正交试验。通过有限元模拟，判断了奥氏体铋不锈钢棒材在不同工艺条件下开裂的可能性，得到了一套最优工艺参数。在极差分析的基础上，讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。设计了五因素四水平的正交试验。通过有限元模拟，判断了奥氏体铋不锈钢棒材在不同工艺条件下开裂的可能性，得到了一套最优工艺参数。在极差分析的基础上，讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。设计了五因素四水平的正交试验。通过有限元模拟，判断了奥氏体铋不锈钢棒材在不同工艺条件下开裂的可能性，得到了一套最优工艺参数。在极差分析的基础上，讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。对含奥氏体铋不锈钢棒材在不同工艺条件下开裂的可能性进行了判断，得到了一套最佳工艺参数。在极差分析的基础上，讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。对含奥氏体铋不锈钢棒材在不同工艺条件下开裂的可能性进行了判断，得到了一套最佳工艺参数。在极差分析的基础上，讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。讨论了各种工艺参数对棒材开裂的影响。然后，基于动态材料模型和Murty准则，建立了含铋易切削奥氏体不锈钢的加工图。发现最佳工艺参数与热加工图的可加工范围一致。最后，采用最佳工艺参数进行现场轧制，结果表明棒材无裂纹。