can be concluded that the spraying parameters of test C is better than test B. Moreover, the maximum residual stress of sample A is lower than sample C, which means that increasing the duration in the second quenching stage has a lower residual stress than improving the peak value of the heat transfer coefficient. It is thus clear that, different from the other methods of reducing residual stress, such as introducing the pre-deformation [28] or lowering the initial quenching temperature [29], the multi-stage quenching