Laser engraving, which is a high-precision and non-contact processing technology, has been widely used to process the difficult-to-cut mould steel. However, the efficiency is still low and the influence of laser engraving on the microstructure and properties of engraved surface also needs further study. By varying the assist gas (Argon, Compressed air, and Oxygen) of nanosecond laser engraving of Cr12MoV mould steel, the material removal rate and surface quality were compared, and the mechanisms of elemental diffusion and microstructural evolution in surface remelting layer were investigated to understand the variation in micro-hardness values. The results showed that the exothermal chemical reactions significantly increased the efficiency of laser engraving, but the surface quality was deteriorated and the detachment of elements C and Cr in remelting layer was promoted. Thus, lower hardness was observed for the remelted layer in the presence of oxygen or compressed air compared to Argon, although the micro-hardness of remelted layers was all increased attributed to grain refinements. Results suggested that the use of oxygen gas during rough engraving increased the material removal rate and reduced the cost, and the use of Argon gas at final engraving steps improved the quality and mechanical properties of the engraved surface.

激光雕刻是一种高精度的非接触式加工技术，在难切削模具钢的加工中得到了广泛的应用。然而，效率仍然很低，激光雕刻对雕刻表面的微观结构和性能的影响还需要进一步研究。通过改变Cr12MoV模具钢纳秒激光雕刻的辅助气体（氩气、压缩空气和氧气），比较材料去除率和表面质量，研究表面重熔层中元素扩散和微观结构演化的机制，以了解显微硬度值的变化。结果表明，放热化学反应显着提高了激光雕刻效率，但表面质量变差，促进了重熔层中元素C和Cr的脱离。因此，与氩气相比，在氧气或压缩空气存在下重熔层的硬度较低，尽管重熔层的显微硬度均因晶粒细化而增加。结果表明，在粗雕过程中使用氧气提高了材料去除率并降低了成本，在最终雕刻步骤中使用氩气提高了雕刻表面的质量和机械性能。