Tensile failure behaviours of Q345 steel welded joint based on acoustic emission and infrared thermography

Welding technology, as the most widely used and mature connection technology in the world, will inevitably be accompanied by various welding defects in practical applications. This study employed acoustic emission (AE) and infrared thermography techniques (IRT) to investigate the damaged evolution of welding joints containing different types of defects through tensile experiments. Cluster algorithms and temperature spectrum variation analyses were applied to characterise the damage progression associated with these defects. The results showed that the slag inclusion specimens exhibited significant skewness in power and amplitude indices, with the highest energy level (4.64). Meanwhile, the coefficient of variation and probability density of temperature changes, along with their thermal characteristics, can effectively identify cracks and incomplete penetration in specimens. The introduced signal parameters supplemented the defect characterisation data, demonstrating that the correlation between AE parameters and thermal behaviour can effectively analyse the damage evolution patterns of different defect types. The integrated inspection approach offers a robust and reliable methodology for assessing structural damage, thereby enhancing its applicability in the structural health monitoring of welded steel frameworks.