Rockwell Hardness B Values for A356-T6 Casting

[USACompositeGuy]

I have an A356-T6 casting that was repair welded and stress relived per AMS 2771. The AMS spec sends you to the material spec which provides Brinell values for process verification coupons. I only have access to a Rockwell B hardness machine and can’t find a conversion factor from Brinell to A356 casting.

The AMS conversion spec provides Brinell to Rockwell B for Wrought aluminum but not castings. Is it acceptable to use these values or can someone point me in the direction of the correct conversion or actual Rockwell B values?

 

[israelkk]

The Brinell to Rockwell doesn't depends on the alloy or the treatment. However, the Brinnel uses a large ball that create large indentation on the metal and therefore takes the average properties of large area. While the Rockwell may use small point (ball or diamond shape). If the casting has voids and the Rockwell point will hit the void you will get errors. Therefore, Brinell is the preferred hardness method for casting because of the large ball.