Stellite welding (using cobalt-based alloys) has been successfully employed to apply a layer with high thermal, corrosion, and wear resistance on the valve face of engine valves.However, issues arise when depositing Stellite powder on valve seats using Plasma Transferred Arc (PTA) welding, as this process can easily lead to defects such as blowholes. During the hardfacing process, trapped air may weaken the valve itself, potentially leading to critical failures if installed in an engine. Therefore, Stellite welds must be free from defects such as cracking, porosity, and insufficient coverage, and should be inspected using non-destructive testing (NDT) methods, including visual inspection and ultrasonic test(UT), during manufacturing. However, these conventional methods are inherently time-consuming and susceptible to operator-dependent inconsistencies, which may result in a high error rate. In order to resolve these drawbacks, an induction infrared thermography system was developed and implemented to inspect welding defects in Stellite overlays on automotive engine valves. The system comprises an infrared camera, an induction coil with an electric power control unit, and a computer that controls the power and waveform of the excitation current in the coil via USB interface, operating in phase-locked mode through LabVIEW software. Valve heads with welding flaws were heated instantly at close range using the induction coil under pulsed excitation, and thermal distributions on the surface were recorded by the infrared camera. Defects on the valve head were successfully detected through differential Joule heating and verified using optical imaging for comparison. More than one hundred defective valves were examined, and all defects were successfully identified within a few seconds, most of which were porosity-type defects (pores) on the order of hundreds of micrometers. Experimental results demonstrated that the induction infrared thermography technique is a fast and potentially effective comprehensive quality inspection method for detecting surface flaws in Stellite welds on engine valve heads.