Thermal effects and deformation mechanisms in abrasive waterjet machining: insights from Ti-6Al-4V alloy for broader applications

As a novel cold machining method, abrasive waterjet machining (AWJM) has significant potential for processing titanium-based materials such as Ti-6Al-4V alloy. However, the thermal effects and material deformation mechanisms of AWJM remain challenging to explain. This study introduces a six-colour blackbody radiation pyrometry method that successfully monitors transient high temperatures during AWJM. The results revealed that temperatures during AWJM were not negligible, reaching up to 3602.08 K, leading to material solidification and oxidation. The flash temperature exhibited transient and continuously oscillating characteristics at the microsecond scale. The combined mechanical and thermal loads created three distinct regions: the jet impact zone (elongated grains, oxide-based compositions, and material melting), the heat-affected zone (larger grains), and the base material zone. In the jet impact zone, a pronounced temperature gradient formed on the surface, promoting grain refinement. However, as the distance from the impact zone increases, the extent of grain refinement diminishes, leading to larger grain sizes. The higher kernel average misorientation values observed in and near the impact zone indicated that high-temperature conditions were insufficient for complete recrystallisation, either because of inadequate diffusion or the short duration of the elevated temperatures. This study reveals the thermal and material deformation mechanisms involved in the AWJM process. This establishes a foundational understanding of the processing of titanium-based and other heat-sensitive materials, ultimately contributing to enhanced overall material performance.