A novel in-situ temperature measurement method for liquid metal embrittlement cracking analysis

Liquid metal embrittlement poses a challenge in resistance spot welding of zinc-coated advanced high-strength steels. Liquid metal embrittlement often leads to surface cracking, which degrades the mechanical properties of the welded joints. Therefore, understanding the liquid metal embrittlement cracking behaviour and developing mitigation strategies are essential. This study proposes the implementation of an infrared camera for in-situ temperature measurement during welding. Given the substantial variation in surface emissivity during resistance spot welding, a temperature correction model is necessary at critical temperatures associated with liquid metal embrittlement onset. This study proposes a temperature correction model that achieves an 85% improvement in accuracy with a 20 °C error. The model is tailored for quantitative analysis of liquid metal embrittlement cracking, utilising the Boltzmann sigmoidal and BiDoesResp functions.