TY - JOUR
T1 - The effect of d0 reference value on a neutron diffraction study of residual stress in a γ/γ' nickel-base superalloy
AU - Rolph, James
AU - Iqbal, Naveed
AU - Hoffman, Michael
AU - Evans, Alex
AU - Hardy, Mark C.
AU - Glavicic, Michael G.
AU - Preuss, Michael
PY - 2013/5
Y1 - 2013/5
N2 - A nickel-base superalloy sub-scale disc has been studied using neutron diffraction to characterise the residual stress distribution following heat treatment. Strain has been calculated using measured neutron diffraction d-spacings in combination with d0 reference values obtained using three distinct methods, namely, measurement of a stress-free cube, a sin2c characterisation (used independently and as a correction factor), and an axial stress balance. In addition, data obtained using the contour method have been included since it allows comparison of diffraction-based data to a technique that does not require a d0 value. In terms of residual stress, agreement between all d0 measurement techniques and the contour method was high, with the exception being those made using the Sin 2ψ technique. An offset of approximately 350 MPa was observed in these data, and a possible systematic error was ascribed to a unique diffraction characteristic of a γ/γ' nickel-base superalloy. A global d 0 value obtained using a stress balance or stress-free cube was found to be reliable throughout the sample bulk in cases where thermal processing was carried out at a slow rate, such as ageing. However, d0 differences equivalent to 400 me were observed between central and surface regions when a global d0 was applied to a water-quenched sample.
AB - A nickel-base superalloy sub-scale disc has been studied using neutron diffraction to characterise the residual stress distribution following heat treatment. Strain has been calculated using measured neutron diffraction d-spacings in combination with d0 reference values obtained using three distinct methods, namely, measurement of a stress-free cube, a sin2c characterisation (used independently and as a correction factor), and an axial stress balance. In addition, data obtained using the contour method have been included since it allows comparison of diffraction-based data to a technique that does not require a d0 value. In terms of residual stress, agreement between all d0 measurement techniques and the contour method was high, with the exception being those made using the Sin 2ψ technique. An offset of approximately 350 MPa was observed in these data, and a possible systematic error was ascribed to a unique diffraction characteristic of a γ/γ' nickel-base superalloy. A global d 0 value obtained using a stress balance or stress-free cube was found to be reliable throughout the sample bulk in cases where thermal processing was carried out at a slow rate, such as ageing. However, d0 differences equivalent to 400 me were observed between central and surface regions when a global d0 was applied to a water-quenched sample.
KW - Neutron diffraction
KW - Nickel superalloy
KW - Residual stress
KW - Sinψ
KW - X-ray diffraction
UR - http://www.scopus.com/inward/record.url?scp=84884556185&partnerID=8YFLogxK
U2 - 10.1177/0309324713486273
DO - 10.1177/0309324713486273
M3 - Article
AN - SCOPUS:84884556185
VL - 48
SP - 219
EP - 228
JO - Journal of Strain Analysis for Engineering Design
JF - Journal of Strain Analysis for Engineering Design
SN - 0309-3247
IS - 4
ER -