Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY) May 2007 REPORT TYPE SPONSOR/MONITOR'S REPORT NUMBER(S) DISTRIBUTION/AVAILABILITY STATEMENTApproved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThe U.S. Army Aviation and Missile Research Development and Engineering Command (AMRDEC), Aviation Engineering Division in Huntsville, AL requested that the U.S. Army Research Laboratory, Weapons and Materials Research Directorate at Aberdeen Proving Ground, MD develop and execute a program aimed at evaluating the shot-peening sensitivity of several aerospace materials. The materials represent the four most common metals utilized on U.S. Army aviation shot-peened components. The study had three main thrusts: to assess the variation in shot-peening intensity expected from various shot-peening parameters, to assess the fatigue strength yielded at prescribed shot-peening intensities, and to correlate surface roughness and x-ray diffraction residual stress analysis data to those prescribed stress intensities. Once the shot-peening parameters' effect on shot-peening intensity was characterized, specific intensities and parameters were selected over an intensity range (dictated by AMRDEC) for each material to assess the sensitivity on fatigue strength.

Internal elastic strain (i.e., residual stress) and the diffracted X-ray intensity variation over several orientations of crystallites with respect to the specimen surface were investigated as a means of differentiating two qualities of polycrystalline nickel plating. A unique instrument based upon a position-sensitive scintillation X-ray detector was used to apply all of the techniques commonly applied to X-ray stress analysis in this investigation. It was concluded that residual stress measurements did not provide a clear distinction between the two specimens, but comparison of the relative intensities diffracted from crystallographic planes at certain orientations with the surface did provide a distinction.

A unique X-ray diffraction instrument for residual stress measurement has been developed that provides for speed, ease of measurement, accuracy, and economy of surface stress measurement. Application of this instrument with a material removal technique, e.g., electropolishing, has facilitated detailed, high resolution studies of three-dimensional stress fields. This paper describes the instrumentation and techniques applied to conduct the residual stress measurement and presents maps of the residual stress data obtained for the surfaces of a heavy 2 1/4 Cr 1 Mo steel plate weldment.

The Pennsylvania State University has developed and tested a miniature x-ray instrument for the measurement of residual stress (strains). The stress head including x-ray source and detection surface is approximately four and one-half inches long and can be inserted into an orifice less than two and one-half inches in diameter. This head is on the end of a several-foot long cable and is extremely manipulatable.The instrumentation design is based upon a unique position sensitive scintillation detector which ie capable of applying the single-exposure x-ray stress measurement technique. Total lapse time data collection periods for aluminum alloys are less than ten seconds with x-ray tube powers of 120 watts. Results from a four-point bend test on an aluminum alloy specimen showed excellent precision. The configuration of the instrument and the procedures for its application are described.

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