Characterization of Creep Damage in Metals Using Small Angle Neutron Scattering

Abstract

Creep damage in polycrystalline metallic materials can be attributed to cavitation and cracking along the grain interfaces. Theories of creep cavitation that have been developed in recent years are reviewed. Further evaluation and/or refinement of these theories has been retarded by a lack of an experimental counterpart. Small angle neutron scattering studies (SANS) provide one experimental tool which is complementary to others. SANS done at NBS and elsewhere have shown that this technique is suitable for studying nucleation and early stage of growth of creep cavities. This would provide the impetus to further progress in this area.

Small angle neutron scattering at the National Institute of Standards and Technology

“…High temperature failure of alloys is often due to slow nucleation and growth of grain boundary cavities. SANS has been used to study both creep cavitation [ 107 , 108 ] and fatigue-induced cavitation [ 109 , 110 , 111 ]. In particular, SANS was used to study void growth in alloy 800 during creep [ 107 ] by measuring the scattered intensity as a function of creep time for six different samples.…”

Application of small angle neutron scattering to study creep cavitation in stainless steel weldments

“…[3][4][5][6] Small angle neutron scattering (SANS) can provide volumetric measurement of cavities up to ,1000 nm in size depending on instrumental set-up, as reviewed by Rustichelli. 7 SANS has previously been applied to investigate precipitates and creep damage in Nimonic alloys [8][9][10][11] and type 304 stainless steel, 12,13 and also to measure cavities in type 316H stainless steel. 3,6,14,15 The SANS technique in complement with quantitative metallography has been shown to be a successful technique for quantifying creep cavities.…”