*2.1. Experimental Material*

In this study, the experimental material is 12CrMoV, and its mechanical properties are tested and shown in Table 1.


**Table 1.** Mechanical property of the experimental material.

In order to discuss and determine the crack effect on stress evaluation, the regular rectangular grooves with different depths and widths were precut in the surface of 12CrMoV by using wire cutting technology, and its sketch map was shown in Figure 1. For experimental requirements, a sample with the size of 280 mm × 40 mm × 7 mm was prepared. In the same sample, the groove depth, the symbol of which is *d* as shown in Figure 1, is the same, and the widths are 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm and 3.0 mm, respectively. For different samples, the groove depths are 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm and 3.0 mm, respectively. To avoid the influence of surface roughness on *H*p(*y*) signal, the surfaces of all samples were rubbed, and its surface roughness was Ra1.2. To avoid the deformation influence of material, the spacing between adjacent grooves is determined as 40 mm, and seven detection lines, the spacing between which is 5.0 mm, are drawn on the surface of sample as shown in Figure 1. To eliminate the initial *H*p(*y*) signal effect caused by machining, all samples were annealed at 860 ◦C in the vacuum heat treatment furnace, the vacuity of which was 8 <sup>×</sup> 10−<sup>4</sup> Pa. Afterwards, the temperature was reduced to 200 ◦C and the samples were taken out from the vacuum heat treatment furnace.

**Figure 1.** The sketch map of the experimental sample with regular rectangular groove.
