ETD 150 stands for elevated temperature drawing. The steel is a 4140 steel that is mechanically drawn to put stresses into the bar. Once the bar is machined especially in a non symmetrical fashion it will have a tendency to move.
A better alternative is a material called FLEXOR. FLEXOR has...
I don't know what carburizing steel you are using but you might consider doing a carburize and anneal first. If you leave stock in the area of the thread you do not want carburized you can bring it back and turn off insuring 100% removal of carburized layer. Then go back to heat treater for...