EMBRITTLEMENT OF BRAZED MARTENSITIC STAINLESS-STEEL

Brazing of AISI 410 martensitic stainless steel (12%Cr) with boron con taining nickel based filler metal was observed to lead to two major em brittlement effects - temper embrittlement and brazement embrittlement . Temper embrittlement, resulting from slow cooling of the material af ter brazing, affects both he dimple rupture and final brittle fracture portions of the impact energy of the material. Brazement embrittlemen t, resulting largely from the fine intra- and intergranular boride pre cipitates in the base metal adjacent to the braze, significantly limit s the extent of dimple rupture before the onset of brittle fracture of the material under impact conditions. A simple analysis is presented which shows that the dimple rupture portion E-d and the brittle fractu re portion E-b of the impact energy are affected differently by the ab ove embrittlement mechanisms. Their order of significance is as follow s: Delta E-d'' > Delta E-d' > Delta E-b', where the double prime and! single prime indicate the energy associated with brazement and temper embrittlement respectively. When both embrittlement effects occur simu ltaneously, brazement embrittlement has a greater effect than temper e mbrittlement in Delta E-d estimation.