基于声发射 Ib 值分析的渗铝 321 钢损伤特性研究

太阳能热发电换热管主要材料渗铝321钢的损伤会导致换热管的寿命缩短甚至断裂，因此必须进行损伤检测。采用声发射方法对渗铝321钢的损伤特性进行分析，实现对换热管性能的在线动态监测。通过采用声发射Ib值特征来表征渗铝321钢的损伤程度，并运用自组织映射(SOM)神经网络算法进行声发射特征参数聚类，以分析材料的损伤模式。结果表明，力学塑性阶段的声发射事件数量剧增，能量和振铃计数的峰值标志着试件的断裂。此外，在试件失效前，Ib值显著降低且密度变密集，表明Ib值的变化特征可以作为材料临界失效的预警信号。通过SOM算法对特征参数进行聚类分析得到4个簇及其对应的特征频率，并使用扫描电子显微镜(SEM)观察试件的断口形貌，得出4个簇分别对应于孔洞生长与汇合、微裂纹成核、宏观裂纹扩展和纤维状断裂4类损伤模式。这项研究旨在探索金属管材的损伤演化行为，并为管材的损伤分析和健康监测提供依据。

Study on damage characteristics of aluminized 321 steel based on acoustic emission Ib-value analysis

The damage to aluminized 321 steel, which is the main material of solar thermal power heat exchange tube, will lead to theshortening or even fracture of the life of the heat exchange tube. Therefore, the damage detection must be carried out. The damagecharacteristics of aluminized 321 steel are analyzed by the acoustic emission (AE) method, and the online dynamic monitoring of heatexchange tube performance is realized. The damage degree of aluminized 321 steel is characterized by using the AE Ib-value feature, andthe self-organized mapping (SOM) neural network algorithm is used to cluster the AE characteristic parameters to analyze the damagemode of the material. The results show that the number of AE events in the mechanical plastic stage increases sharply, and the peakvalues of energy and ringing count indicate the fracture of the specimen. In addition, before the failure of the specimen, the Ib-value issignificantly reduced and the density becomes dense, indicating that the variation characteristics of the Ib-value can be used as an earlywarning signal for the critical failure of the material. Four clusters and their corresponding characteristic frequencies are obtained byclustering analysis of the characteristic parameters through the SOM algorithm. The fracture morphology of the specimen is observed byscanning electron microscope ( SEM). The four clusters correspond to four types of damage modes, including hole growth andcoalescence, micro-crack nucleation, macro-crack propagation, and fibrous fracture. This study aims to explore the damage evolutionbehavior of metal pipes and provide a basis for damage analysis and health monitoring of pipes.