Materials Week '97: Tuesday AM Session

Focusing on physical metallurgy and materials, Materials Week '97, which incorporates the TMS Fall Meeting, features a wide array of technical symposia sponsored by The Minerals, Metals & Materials Society (TMS) and ASM International. The meeting will be held September 14-18 in Indianapolis, Indiana. The following session will be held Tuesday morning, September 16.

TESTING AND INSPECTION TECHNIQUES FOR STRUCTURAL INTEGRITY EVALUATION AND POWER PLANT LIFE EXTENSION: Session III: Pressure Vessel Steels--Mechanical and Fracture Properties & Radiation Embrittlement

Session Chair: Prof. K. Linga Murty, Department of Nuclear Engineering and Department of Materials Science & Engineering, North Carolina State University, Raleigh, NC 27695-7909; Mr. Fahmy M. Haggag, Advanced Technology Corporation, 661 Emory Valley Road, Suite A, Oak Ridge, TN 37830

CHARACTERIZATION OF PRESSURE VESSEL STEELS AND THEIR WELD GRADIENT PROPERTIES UTILIZING THE ABI TECHNIQUE: EFFECTS OF TEMPERATURE: Peter Q. Miraglia, K. Linga Murty, North Carolina State University, Nuclear Engineering Department, Raleigh, NC 27695-7909; Fahmy M. Haggag, Advanced Technology Corporation, 661 Emory Valley Road, Suite A, Oak Ridge TN 37830; Vikram N. Shah, Idaho National Engineering Laboratories, P.O. Box 1652, Idaho Falls, ID 83415-3870

The mechanical properties of nuclear pressure vessel weld material were characterized using the stress-strain-microprobe (SSM) based on the automated ball indentation (ABI) technique with the express purpose of evaluating gradient properties varying from the base, heat-affected-zone (HAZ), and the weld nugget. ABI-derived stress vs strain curves correlated with the conventional destructive tensile tests which were also performed on SSM using sub-size specimens. Mechanical properties derived from the ABI tests include yield strength, strength coefficient, strain hardening exponent (uniform ductility), and Brinell hardness. In addition, the tensile strengths are estimated from these data using the strain-hardening relation. In this particular weld, the strength properties of the weld nugget were bracketed by the base and HAZs. ABI tests clearly demonstrated the viability of SSM in characterizing localized properties in systems with gradient properties with least amount of specimen preparation, and in much shorter time period when compared to the conventional destructive tests which involve tedious and extensive specimen preparation. In addition, since ABI tests leave a very small impression with compressive residual stresses and no stress concentrations, the technique is regarded essentially non-destructive. The effect of temperature on the ABI-derived mechanical properties is being studied from -150°C to 250°C with the main aim being the development of correlations with fracture energies and DBTT. Experimental results, data analyses, and fracture correlations to-date will be presented. This project has been funded by the INEL University Research Consortium. The INEL is managed by Lockheed Martin Idaho Technologies Company for the U.S. Department of Energy, Idaho Operations Office, under Contract No. DE-ACO7-94ID13223.

8:50 am

RADIATION EMBRITTLEMENT PREDICTION MODELS, AND IMPACT OF HEAT-AFFECTED ZONE MATERIALS TO RADIATION EMBRITTLEMENT AND ANNEALING RECOVERY: J.A. Wang, Computational Physics and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6370; Fahmy M. Haggag, Advanced Technology Corporation, 661 Emory Valley Road, Suite A, Oak Ridge, TN 37830; K. Linga Murty, North Carolina State University, Raleigh, NC 27695-7909

Abstract not available.

9:10 am

THE EFFECTS OF SIDE GROOVES ON THE DUCTILE-TO-BRITTLE TRANSITION BEHAVIOR OF SUBSIZE CHARPY SPECIMENS: David J. Alexander, Metals and Ceramic Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6151

It has been suggested that by machining side grooves of appropriate dimensions on subsize Charpy specimens the same ductile-to-brittle transition temperature (DBTT) can be measured as would be obtained with standard full-sized specimens. Therefore, small half-size Charpy specimens have been fabricated from A 533 grade B class 1 pressure vessel steel. Side grooves of 0, 10, and 20% of the specimen thickness were machined on each side of the specimens. These specimens were tested and compared to previous data generated with full-size specimens. The measured DBTTs will be compared, and the effects of the side grooves on the DBTT will be discussed. Also, the effects of the side grooves on the upper-shelf energy levels will be considered.

9:30 am

NOVEL METHODS TO DETERMINE FRACTURE TOUGHNESS AND CHARPY IMPACT PROPERTIES FROM AUTOMATED BALL INDENTATION TESTS: T. Byun, Korea Atomic Energy Research Institute, Taejon, S. Korea; Fahmy M. Haggag, Advanced Technology Corporation, 661 Emory Valley Road, Suite A, Oak Ridge TN 37830; K. Linga Murty, North Carolina State University, Raleigh, NC 27695-7909

Abstract not available.

9:45 am

A UNIFIED TOUGHNESS MASTER CURVE-SHIFT METHOD FOR USING SMALL SPECIMENS: G.R. Odette, Department of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106

Abstract not available.

10:00 am BREAK

10:10 am

DYNAMIC STRAIN AGING IN BASE AND WELD METAL OF SA106 GR.C PIPING STEEL: J.W. Kim, I.S. Kim, Department of Nuclear Engineering, Korea Advanced Institute of Science and Technology, 373-9, Mabuk-ri, Kusong-gu, Taejon 305-701, Korea; I.S. Ra, K.K. Jee, Korea Power Engineering Company, Inc., 360-9, Mabuk-ri, Kusong-myon, Yongin, 44-910, Korea

The characteristics of dynamic strain aging (DSA) in base and weld metal of SA106 Gr.C piping steel were examined through tensile and J-R testing carried out under various temperatures and loading rates. Results indicated that both metals were susceptible to DSA at a certain range of temperature, including nuclear power plant operating temperature, which depended on strain rate. DSA temperature range of weld metal was broader and appeared higher temperatures than that of base metal. This might be caused by smaller grain size and higher Mn content in weld metal. Crack initiation resistance, J_i, and crack growth resistance, dJ/da, in DSA region were about 40% lower than those at RT for both metals.

10:30 am

A CONFOCAL MICROSCOPY-FRACTURE RECONSTRUCTION METHOD TO MEASURE DYNAMIC FRACTURE TOUGHNESS IN SUBSIZED FRACTURE SPECIMENS: G.R. Odette, E. Donahue, G.E. Lucas, Department of Mechanical Engineering and Materials, University of California, Santa Barbara, CA 93106

Abstract not available.

10:50 am

USE OF A STRESS-STRAIN MICROPROBE FOR MATERIAL TESTING: N.F. Panayotou, D.G. Baldrey, Lockheed Martin, Schenectady, NY 12301

The Stress-Strain Microprobe (SSM) uses an automated ball indentation technique to obtain flow data from a localized region of a test specimen or component. This technique is being used to rapidly determine the yield strength and microstructural condition of a variety of materials including pressure vessel steels, stainless steels and nickel-base alloys. The SSM provides an essentially nondestructive technique for the measurement of local yield strength data. This technique is especially suitable for the study of complex or highly variable microstructures such as weldments and weld heat affected zones. In this study yield strength data measured by the SSM are discussed and where possible compared to data obtained by conventional tensile tests. The sensitivity of the SSM to the presence of residual stresses is also discussed.