Evaluating fracture toughness distributions of laser cladding repaired hydrogenation reactors by spherical indentation tests (SITs)

Abstract

Laser cladding repairing provides reliable technical support for the remanufacturing of hydrogenation reactors. However, its repair quality can be significantly affected by process parameters, material aging, and a variety of other factors, urgently demanding an in-situ evaluation method to ensure service reliability of remanufactured hydrogenation reactors. In this case, this study provides an extensive experimental investigation on the fracture toughness predictions by spherical indentation tests (SITs). Firstly, SIT-based fracture toughness predictions are conducted on repaired specimens under optimal process parameters, which indicates significant ductile-to-brittle transitions can be observed in different regions of repaired specimens, together with obvious initial damage existing in both the cladding zone and interface. These factors significantly impact the prediction accuracy of meso-damage mechanics-based models, while the critical stress-critical strain criterion demonstrates superior capability in predicting ductile-to-brittle transitions across different zones. Subsequently, the critical stress-critical strain criterion is employed to investigate the fracture toughness distributions under different process parameters and aging status. It is found that compared to conventional large-scale sampling, the localized characteristics enable SITs providing more precise acquisition of fracture toughness distribution, thus facilitates identification and evaluation of the weakest part of repaired specimens.