对QT700-2球墨铸铁进行单道和非对称多道激光淬火处理，研究不同工艺激光淬火后球墨铸铁的表面硬度和硬化层深度。结果表明：单道激光淬火后，球墨铸铁的表面硬度在52~59 HRC，表面硬度随着激光功率的增加而升高，随着扫描速度的增大先升高后略微降低；在激光功率1 300 W、扫描速度8 mm·s^-1下，球墨铸铁的表面硬度基本在55~58 HRC，表面硬度分布较均匀，硬化层深度约为1 mm.不同工艺参数下非对称多道激光淬火后，球墨铸铁表面的硬度均大于52 HRC；当前一道激光功率为1 200 W，扫描速度为6 mm·s^-1，后一道激光功率为1 300 W，扫描速度为8 mm·s^-1时，球墨铸铁的表面硬度较高，且硬度波动较小，在距表面0.3 mm处的软化区宽度约为4.0 mm，非软化区和软化区的硬化层深度分别约为1.0，0.5 mm。

QT700-2 ductile cast iron was treated by single-pass and asymmetric multi-pass laser quenching processes, and then the surface hardness and hardened layer depth of the ductile cast iron under different laser quenching processes were studied. The results show that after single-pass laser quenching, the surface hardness of the ductile cast iron was 52-59 HRC; the surface hardness increased with increasing laser power, and increased first and then decreased slightly with increasing scanning speed; with laser power of 1 300 W and scanning speed of 8 mm·s^-1, the surface hardness of the ductile cast iron evenly distributed at 55-58 HRC, and the hardened layer depth was about 1 mm. After asymmetric multi-pass laser quenching with different process parameters, the surface hardness of the ductile cast iron was greater than 52 HRC; with the previous pass laser power of 1 200 W and scanning speed of 6 mm·s^-1, and the latter pass laser power of 1 300 W and scanning speed of 8 mm·s^-1, the surface hardness of the ductile cast iron was relatively high, and the fluctuation of hardness was relatively small; the width of the softened zone at 0.3 mm from the surface was about 4.0 mm, and the hardened layer depths in the non-softened zone and in the softened zone were about 1.0, 0.5 mm, respectively.