Influence mechanism of heat and mass transfer behaviors on kerf quality and cutting efficiency of thick steel plates using laser-flame hybrid cutting

This paper investigated the influence mechanism of heat and mass transfer behavior on kerf quality and cutting efficiency during laser-flame hybrid cutting (LFHC) for thick steel plates. The evolution of kerf morphology and quality characteristics with laser power, cutting gas pressure, and cutting speed was systematically analyzed, and the cutting performance of LFHC was evaluated against existing cutting technologies. The results indicate that the perpendicularity tolerance ( u ) and surface roughness ( Ra ) of the kerf initially decrease and then stabilize with increasing laser power. As the cutting gas pressure gradually rises, both the u and Ra first decrease and then increase. Conversely, higher cutting speeds result in increased u and Ra . Under the optimized process parameters, LFHC can cut 50-mm-thick steel plates at a speed of 500 mm/min with a high-quality kerf. The maximum cutting speed of LFHC can reach 700 mm/min, which surpasses existing cutting technologies. Additionally, the oxy-fuel flame can suppress temperature fluctuation at the cutting front, thereby significantly reducing the depth of cutting striations. The intrinsic relationship between heat-mass transfer behavior and cutting performance in LFHC involves that higher kerf temperature and more intense oxy-iron reaction significantly improve the melting efficiency of the metal. Furthermore, the cutting oxygen with good flow field characteristics enables lower-viscosity molten metal to be ejected from the kerf more steadily and efficiently. These findings provide valuable insights for cutting thick steel plates with high efficiency and superior quality, holding the vital industrial value in shipbuilding and engineering machinery.