By -
Date 04-27-2005 12:41
Doug,
17-4 is a martensitic type of PH material. When the 17-4 is solution annealed at about 1900F., the structure is mostly austenite. As it cools down to between 300 and 200F, the austenite transforms to martensite. After being quenched to this matrensitic structure, the 17-4 is strengthened by a precipitation mechanism during the aging heat treatment. Normally, in my experience, the interpass for a 17-4, using the 630 filler metal, which is recommended for welding the 17-4, is 150C (300F).
Chuck