In this study, the connection between total strain energy density and fracture surface topography is investigated in additively manufactured maraging steel exposed to low-cycle fatigue loading. The specimens were fabricated using laser beam powder bed fusion (LB-PBF) and examined under fully-reversed strain-controlled setup at strain amplitudes scale from 0.3% to 1.0%. The post-mortem fracture surfaces were explored using a non-contact 3D surface topography measuring system and the entire fracture surface method. The focus is on the relationship between fatigue characteristics, expressed by the total strain energy density, and the fracture surface topography features, represented by areal, volume, and fractal dimension factors. A fatigue life prediction model based on total strain energy density and fracture surface topography parameters is proposed. The presented model shows good accordance with fatigue test results and outperforms other existing models based on the strain energy density. This model can be useful for post-failure analysis of engineering elements under low-cycle fatigue, especially for materials produced by additive manufacturing (AM).

中文翻译：

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增材制造 18Ni300 钢 LCF 寿命预测的应变能密度与整个断口参数关系

在本研究中，研究了暴露于低周疲劳载荷的增材制造马氏体时效钢的总应变能密度与断裂表面形貌之间的联系。使用激光束粉末床熔合 (LB-PBF) 制造样本，并在完全反向应变控制设置下以 0.3% 至 1.0% 的应变幅度进行检查。使用非接触式 3D 表面形貌测量系统和整个断裂表面方法来探索死后断裂表面。重点是疲劳特性（用总应变能密度表示）与断裂表面形貌特征（用面积、体积和分形维数因子表示）之间的关系。提出了一种基于总应变能密度和断裂表面形貌参数的疲劳寿命预测模型。所提出的模型与疲劳测试结果具有良好的一致性，并且在应变能密度方面优于其他现有模型。该模型可用于低周疲劳下工程元件的失效后分析，特别是对于增材制造 (AM) 生产的材料。