Laser cladding holds the promise to repair damaged rails, including flange tip lift crossings (FTLC) in tram rails. In order to further understand the effectiveness of laser cladding against rail damage, this study investigated the ratcheting behaviour of the laser cladding alloy Stellite 21, used in FTLC repairs, in comparison to the currently used rail steel grade R260. Experimental studies were conducted under uniaxial and biaxial stress-controlled cyclic loads. The study found that under identical uniaxial stress conditions, Stellite 21 exhibits superior ratcheting behaviour compared to R260 steel. Various mean stresses and stress amplitudes were also studied, revealing that increases in mean stresses or stress amplitudes resulted in higher ratcheting strains and ratcheting strain rates. Additionally, biaxial compression-torsion cyclic loading tests were performed on the R260 to replicate real-life stress conditions. The results indicated that the direction of plastic strain accumulation depended on the direction of the applied non-zero mean stress. The findings from this study are essential for calibration of parameters of cyclic plasticity models, which can be used to simulate ratcheting performance of laser-cladded FTLCs under in-service conditions for the prediction of fatigue crack initiation life and maintenance requirements of flange tip lift crossings.

中文翻译：

---

Stellite 21 作为翼缘尖端提升道口维修的激光熔覆材料的棘轮行为


激光熔覆有望修复受损的轨道，包括有轨电车轨道中的法兰尖端提升交叉口 （FTLC）。为了进一步了解激光熔覆对钢轨损坏的有效性，本研究调查了 FTLC 维修中使用的激光熔覆合金 Stellite 21 与目前使用的钢轨钢等级 R260 的棘轮行为。在单轴和双轴应力控制的循环载荷下进行了实验研究。研究发现，在相同的单轴应力条件下，与 R260 钢相比，Stellite 21 表现出卓越的棘轮行为。还研究了各种平均应力和应力幅值，结果表明平均应力或应力幅值的增加导致更高的棘轮应变和棘轮应变率。此外，还对 R260 进行了双轴压缩扭转循环载荷测试，以模拟现实生活中的应力条件。结果表明，塑性应变积累的方向取决于施加的非零平均应力的方向。本研究的结果对于循环塑性模型参数的校准至关重要，可用于模拟激光熔覆 FTLC 在服役条件下的棘轮性能，以预测疲劳裂纹萌生寿命和法兰尖端提升交叉的维护要求。