Regarding the issue of crack from machining process of B30PH, thk.250, we get reply from the technical department of Baosteel as follow:
From the photo, there may be a small crack( could not find by eye) on the surface of plate and it is extend to crack (can be seen by eye) after a long time stress releasing from the year 2013 to now. The cracks is not regular and not only one crack. It should be find by eye after cutting.
1. confirm the depth of crack
2. cut the area with crack stopping the extend of the crack
3. if the area is cleared or avoid, the other area won't be effect by the crack
4. from the photo, there is the possibility that the crack is produced during the plate is cutting or machining and extend after that