Journal Published Online: 17 May 2018
Volume 7, Issue 4

Multi-Technique Residual Stress Measurements to Quantify Stress Relief of 7085-T7452 Aluminum Die Forgings



This article describes the use of complementary residual stress measurements to quantify cold-work stress relief in die forgings used for monolithic unitized aerospace components. Two specimens were used, being nominally identical, but measured at different processing stages: one that was die forged and quenched (high residual stress state) and one having a post-quench, cold-work stress relief (low residual stress state). Multi-component residual stress maps were developed using multiple techniques along a single measurement plane (axes of this plane run parallel to the nominal long-transverse [x-direction] and short-transverse directions [y-direction]). The measurement techniques were energy dispersive X-ray diffraction (EDXRD), neutron diffraction (ND), and primary slice removal (PSR) biaxial mapping. Good agreement was found between the EDXRD and PSR biaxial mapping measurements. In the high-stress specimen, measured stress normal to the measurement plane (z-direction [L]) is highly compressive along the part exterior (−300 MPa) and highly tensile toward the center (250 MPa), as typical of quenched aluminum. Stress along the x-direction has a similar spatial distribution but smaller magnitude (−200 MPa to 130 MPa). The measured stresses in the cold-worked, low-stress specimen are significantly lower, with z-direction and x-direction stresses ranging between −130 MPa and 75 MPa.

Author Information

Olson, Mitchell D.
Hill Engineering, LLC, Rancho Cordova, CA, USA
Spradlin, Thomas J.
Air Force Research Laboratory, Wright-Patterson AFB, OH, USA
DeWald, Adrian T.
Hill Engineering, LLC, Rancho Cordova, CA, USA
Hill, Michael R.
Department of Mechanical and Aerospace Engineering, University of California, Davis, CA, USA
Pages: 24
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Stock #: MPC20170105
ISSN: 2379-1365
DOI: 10.1520/MPC20170105