In situ strained Inconel 718 superalloy studied by thermoelectric power technique

Changes in the thermoelectric power of a Ni base superalloy induced by elastic and plastic strain

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a b s t r a c tInduced changes in the thermoelectric power (TEP) of the Inconel 718 by elastic and plastic strain have been previously reported by López Cuéllar et al [1]. Now, in this work, the TEP of a nickel-based superalloy Waspaloy with different heat treatments has been followed during stressing tests.

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“…This mechanical test machine (MTM) was previously described [1] and allows to measure the sample's TEP, strain and stress during tensile tests. TEP measurements were obtained with a TEP Techlab PK120 with Copper blocks.…”

“…Samples with ␥ has shown important TEP, attaining ∼160 nV/ • C for higher strain levels, while samples without ␥ has shown lower variations of ∼20 nV/ • C. Moreover, like for the Inconel, TEP of samples with ␥ phase, have shown a strong lineal behaviour with elastic and plastic strains, which is a very interesting result from the point of view of determination of material's residual stress and plastic deformation. Finally, the lineal model previously reported [1], that predicts the TEP behaviour during tensile tests, is validated with the Waspaloy system, presenting also a statistical analysis of the variation between the experimental results and the expected values from the model.…”

“…Another negative effect on the forgeability is the fast precipitation of ␥ at forging temperatures, which increases the forging forces required. In this sense, in a recent work it has been reported that the thermoelectric power (TEP) for a Nibase superalloy (Inconel 718), is sensitive to non-desirable phase and is clearly affected by the elastic and plastic strain induced during tests [1,3]. In consequence, the TEP characterization technique can be considered useful to follow elastic and plastic strain, and for the study of residual stress in the Inconel 718 alloy.…”

“…For this purpose, a special tensile machine that allows the stress and strain control during TEP measurements was utilized [1]. Samples with ␥ has shown important TEP, attaining ∼160 nV/ • C for higher strain levels, while samples without ␥ has shown lower variations of ∼20 nV/ • C. Moreover, like for the Inconel, TEP of samples with ␥ phase, have shown a strong lineal behaviour with elastic and plastic strains, which is a very interesting result from the point of view of determination of material's residual stress and plastic deformation.…”