Hydrogen trapping by VC precipitates and structural defects in a high strength Fe–Mn–C steel studied by small-angle neutron scattering

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 8740To link to this article : Keywords:Small-angle neutron scattering Hydrogen embrittlement Hydrogen trapped by nanoprecipitates a b s t r a c t The trapping of hydrogen by VC precipitates and structural defects in high strength Fe-Mn-C steel was studied by small angle neutron scattering. No interaction between H and V in solid solution has been detected but a significant interaction between H and structural defects introduced by plastic deformation has been measured. This last effect was reversible upon outgassing of the H. Moreover a significant interaction between H and VC precipitates has been measured; 5 ppm wt. of H could be trapped in the precipitates. This is consistent with the homogeneous trapping of H within the precipitates rather than at the precipitate/matrix interface.

Understanding and mitigating hydrogen embrittlement of steels: a review of experimental, modelling and design progress from atomistic to continuum

“…As such, this can be a powerful tool for hydrogen analysis, such as in protein crystallography and hydride analysis. Neutron techniques have also been employed in examining steels [125,219], where one should expect that with the addition of hydrogen, the total scattering should increase. Indeed, this is observed in small-angle neutron scattering (SANS) data, where charged samples of finely dispersed vanadium carbide precipitates appear to slightly increase the total scattered intensity after hydrogen-1 charging [152], and after subsequent annealing, the scattered intensity is reduced back to the uncharged state.…”

Microstructure distribution in an AA2050 T34 friction stir weld and its evolution during post-welding heat treatment

“…At small scattering vectors, the q À4 scattering behavior is due to the presence of the intermetallics and dispersoids. In this range of scattering vectors and in the absence of hardening precipitates, there also can be a small contribution of the dislocation density, however with a smaller power law exponent (of the order of À3) [39,40]. This scattering contribution is observed to decrease from the base metal to the nugget material.…”

Direct observation of individual hydrogen atoms at trapping sites in a ferritic steel

“…Hydrogen trapping in bulk samples is studied by several methods, such as Small-Angle Neutron Scattering (17), Thermal Desorption Spectroscopy (15) (18), and Energy Recoil Detection (19). These methods provide only bulk-averaged information on microstructural interaction, and the direct interpretation from these signals is difficult.…”

“…This is partly due to the limited number of atoms involved. Indeed, an ongoing debate exists about whether the hydrogen is at the surface (39), or penetrates into the carbide itself (17). Previous qualitative APT analysis suggests that this may be a surface effect (32), but no quantitative data confirms this result.…”