DUPLEX AND SUPERDUPLEX

[chtimi]

What are the controls to detect the sigma phase in a DUPLEX-SUPERDUPLEX cast casing with different thicknesses.
You can have good mechanical results and big problem during and after machining even if,the liquid penetrant test is ok before machining!
Thank you for your help.

 

[bruv]

Are you sure that it's sigma causing the problem, seeing as your mechanical test results are OK.

Where on your casting is the problem occuring?

What heat teatment are you using?

Try this, if you don't already - Cast test pieces of the same thickness as the casing, and put them through heat treatment with the casing. Take test pieces from the 1/4 or 1/2 way through the thickness of the test piece. These will give you an idea if the H/T you are using is OK before (possibly) re-H/T ing the casting.

Good luck