The super-duplex stainless steel UNS S32750 consists of two main phases, austenite and ferrite, which differ not only by their morphology, physical, and mechanical properties, but also by their deformation behaviour. A heterogenous deformation can be obtained during thermomechanical processing, generating internal stresses and sometimes fissures or cracks on sample lateral surfaces, due to ferrite’s phase lower potential of plastic deformation accommodation in comparison with austenite phase. The research objective is to determine the optimum range of the applied deformation degree, during hot deformation processing by upsetting of the super-duplex steel (SDSS) UNS S32750. In the experimental program several samples were hot deformed by upsetting, by applying a deformation degree between 5–50%, at 1050 °C and 1300 °C. The most representative hot-deformed samples were selected and analysed by scanning electron microscope-Electron Backscatter Diffraction (SEM-EBSD), to determine the main microstructural characteristics obtained during thermomechanical processing. When considering the experimental results, the influence of the applied deformation degree on the microstructure has been evaluated. Microstructural features, such as nature, distribution, morphology and relative proportion of constituent phases, Grain Reference Orientation Deviation (GROD), and recrystallization (RX), were analysed, in correlation with the applied deformation degree. Finally, it was concluded that the UNS S32750 alloy can be safely hot deformed, by upsetting, at 1050 °C and 1300 °C, with a maximum applied deformation degree of 20% at 1050 °C and, respectively, by 50% at 1300 °C.

中文翻译：

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UNS S32750超级双相不锈钢（SDSS）合金的热变形行为评估

超级双相不锈钢UNS S32750由奥氏体和铁素体这两个主要相组成，这两个相不仅在形貌，物理和机械性能上不同，而且在变形性能上也不同。在热机械加工过程中，由于奥氏体相较铁素体相具有较低的塑性变形适应能力，因此在热机械加工过程中会产生异质形变，从而产生内部应力，有时在试样侧面产生裂缝或裂纹。研究目的是通过热轧超双相钢（SDSS）UNS S32750来确定热变形过程中施加变形程度的最佳范围。在实验程序中，通过在1050°C和1300°C下施加5％至50％的变形度，通过up粗使几个样品热变形。选择最具代表性的热变形样品，并通过扫描电子显微镜-电子背散射衍射（SEM-EBSD）进行分析，以确定在热机械加工过程中获得的主要显微组织特征。当考虑实验结果时，已评估了变形量对显微组织的影响。与所施加的变形程度相关，分析了微观结构特征，例如组成相的性质，分布，形态和相对比例，晶粒参考取向偏差（GROD）和重结晶（RX）。最后得出的结论是，通过在1050°C和1300°C下up粗，可以安全地对UNS S32750合金进行热变形，在1050°C时最大变形量分别为20％，在1300°C时最大变形量为50％。 ℃。