The present study aimed to study ratcheting strains of corroded stainless steel 304LN elbow pipes subjected to internal pressure and cyclic bending moment. To this aim, spherical and cubical shapes corrosion are applied at two depths of 1 mm and 2 mm in the critical points of elbow pipe such as symmetry sites at intrados, extrados, and crown positions. Then, a Duplex 2205 stainless steel elbow pipe is considered as an alternative to studying the impact of the pipe materials, due to its high corrosion resistance and strength, toughness, and most importantly, the high fatigue strength and other mechanical properties than stainless steel 304LN. In order to perform numerical analyzes, the hardening coefficients of the materials were calculated. The results highlight a significant relationship between the destructive effects of corrosion and the depth and shape of corrosion, so that as corrosion increases, the resulting destructive effects increases as well, also, the ratcheting strains in cubic corrosions have a higher growth rate than spherical corrosions. In addition, the growth rate of the ratcheting strains in the hoop direction is much higher across the studied sample than the axial direction. The highest growth rate of hoop strain was observed at crown and the highest growth rate of axial strains occurred at intrados position. Altogether, Duplex 2205 material has a better performance than SS 304LN.

本研究旨在研究腐蚀的304LN不锈钢弯管在内部压力和循环弯矩作用下的棘轮应变。为了这个目的，在肘管的关键点（例如，拱门，拱门和拱顶位置的对称部位），在1mm和2mm的两个深度处应用了球形和立方体腐蚀。然后，由于双相2205不锈钢弯头管具有高耐腐蚀性和强度，韧性，最重要的是，其高疲劳强度和其他机械性能比304LN不锈钢高，因此被认为是研究管材影响的替代方法。 。为了进行数值分析，计算了材料的硬化系数。结果表明，腐蚀的破坏作用与腐蚀的深度和形状之间存在显着的关系，因此，随着腐蚀的增加，破坏作用也随之增加，而且立方腐蚀中的棘轮应变的生长速率也高于球形腐蚀。 。此外，棘轮应变在环向方向上的增长率在整个研究样本中要比轴向方向高得多。在冠部观察到最高的环向应变增长率，而在椎弓内位置观察到最高的轴向应变增长率。总而言之，Duplex 2205材料的性能优于SS 304LN。立方腐蚀中的棘轮应变比球形腐蚀中的棘轮应变具有更高的增长率。此外，棘轮应变在环向方向上的增长率在整个研究样本中要比轴向方向高得多。在冠部观察到最高的环向应变增长率，而在椎弓内位置观察到最高的轴向应变增长率。总而言之，Duplex 2205材料的性能优于SS 304LN。立方腐蚀中的棘轮应变比球形腐蚀中的棘轮应变具有更高的增长率。此外，棘轮应变在环向方向上的增长率在整个研究样本中要比轴向方向高得多。在冠部观察到最高的环向应变增长率，而在椎弓内位置观察到最高的轴向应变增长率。总而言之，Duplex 2205材料的性能优于SS 304LN。