My interpretation of this statement is a location of stress concentration in the casting that could result in either local permanent deformation or fracture.
If I am machining a part made from a casting and the drawing indicates a critically stressed area then I might observe caution? Is the critically stressed area do to un-equal cooling rates?
Does the fabrication drawing have specific requirements listed under notes or some other reference regarding surface finish or contour for this critically stressed area? I would use caution, and find out exactly what the requirements are for this location.
My sense is that you might be fabricating this part from an out-dated drawing? If so, you might be forced to interpret this statement on your own. I don't believe that it relates to un-equal cooling rates from the casting process.
One other thought that I had was that the critically stressed area of the casting may have been specified, by the designer, for local volumetric (RT) and surface nondestructive testing.
