Materials Week '97: Monday PM 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 Monday afternoon, September 15.

TESTING AND INSPECTION TECHNIQUES FOR STRUCTURAL INTEGRITY EVALUATION AND POWER PLANT LIFE EXTENSION: Session II: Structural Metals--Radiation and Thermal Effects

Session Chairs: Mr. Fahmy M. Haggag, Advanced Technology Corporation, 661 Emory Valley Road, Suite A, Oak Ridge TN 37830; Prof. In Sup Kim, Department of Nuclear Engineering, Korea Advanced Institute of Science and Technology, S. Korea

EFFECT OF LONG-TERM THERMAL AGING ON THE FRACTURE TOUGHNESS OF AUSTENITIC STAINLESS STEELS: H. Huang, ICF Kaiser Hanford Company, MSIN X3-85, Richland, WA 99352

Austenitic stainless steels (SS) are know to exhibit adequate strength, excellent resistance to sodium, and high fracture toughness. Because of these advantages, the steels are used in the components of nuclear reactors. Compact tension specimens taken from Fast Flux Test Facility (FFTF) primary piping materials (Type 316 stainless steel and 16-8-2 SS weld metal) and from reactor vessel materials (304 SS and 308 SS weld metal) were heated in laboratory furnaces for 100,000 hours. Fracture toughness testing was performed on these specimens, which are 7.62- and 25.4-mm thick, respectively, at the aging temperature (482 and 427C). Results were analyzed with the multiple-specimen method. Thermal aging continues to reduce the fracture toughness of FFTF component materials. Results show that thermal aging has a strong effect on the toughness degradation of weld metals, particularly for 16-8-2 SS weld whose aged/unaged Jc ratio is only 0.31 after 100,000-hour aging. The fracture toughness of the 308 and 16-8-2 SS weld metals fluctuated during 20,000 to 50,000-hour aging but deteriorated as the aging time increased to 100,000 hours. The need to consider fracture control based on a fracture mechanics approach in design and safety analyses for operation exceeding 100,000 hours is discussed.

2:20 pm

SMALL SPECIMEN TECHNIQUES USED TO MEASURE THE EFFECT OF IRRADIATION ON THE MECHANICAL PROPERTIES OF STRUCTURAL MATERIALS FOR THE ACCELERATOR PRODUCTION OF TRITIUM PROJECT: A. Maloy, W.F. Sommer, MST-4, Los Alamos National Laboratory, Los Alamos, NM 87545; D.J. Alexander, K. Farrell, R. Klueh and M.L. Grossbeck, Oak Ridge National Laboratory, Oak Ridge, TN 37831; M.L. Hamilton, Pacific Northwest Laboratories, Richland, WA 99352

For determining the lifetime of target/blanket components for the accelerator production of tritium project, the mechanical properties are being measured after irradiation in prototypic proton and neutron fluxes produced using a 800 MeV, 1mA Gaussian proton beam (where 2 sigma is 3 cm). Small specimen techniques must be used to obtain a uniform fluence on the specimens at a prototypic temperature. Thus, small-scale specimens are being used to measure tensile, bend, creep, fracture toughness, and stress corrosion cracking properties after irradiation. The properties measured with these small-scale specimens will be compared with those measured with larger specimens.

2:40 pm

USE OF THE ABI TECHNIQUE TO ASSESS RADIATION EMBRITTLEMENT AND QUANTIFY TOUGHNESS RECOVERY FOLLOWING THERMAL ANNEALING OF NUCLEAR PRESSURE VESSELS: 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.

2:55 pm

SMALL PUNCH AND TEM DISC TESTING TECHNIQUES AND THEIR APPLICATION TO CHARACTERIZATION OF RADIATION EMBRITTLEMENT: J. Kameda, Ames Laboratory, Iowa State University, Ames, IA 50011; X. Mao, Department of Mechanical Engineering, The University of Calgary, Calgary, Alberta, Canada T2N 1N4

The present paper summarizes the development of miniaturized small punch (SP) and TEM disk testing techniques and shows their applicability in strength, difficulty and fracture toughness were empirically estimated by analyzing the deformation and fracture properties observe in miniaturized specimen tests. A correlation between the ductile-brittle temperature (DBTT) determined from the static SP and dynamic Charpy V-notched specimens tests has been theoretically and experimentally presented. The problems of cracking detection and data scattering often observed in the miniaturized specimen tests are discussed in terms of heterogeneous embattlement behavior of materials. It has been shown that miniaturized testing miniaturized testing techniques have capability of evaluating changes in the mechanical properties of ferritic and vanadium alloys caused by neutron irradiation and post-irradiation annealing. This work was supported by USDOE, Office of Basic Energy Sciences, Div. of Materials Science under contract no. W-7405-ENG-82.

3:15 pm BREAK

3:25 pm

A NOVEL TECHNIQUE TO MEASURE THE MATRIX CARBON COMPOSITION WITH AGEING OF 2.25Cr-1Mo BOILER STEEL: C. Orchard, B.J. Diak, S. Saimoto, Department of Materials and Metallurgical Engineering, Queen's University, Kingston, Ontario, Canada K7L 3N6

The classic work of Baker and Nutting developed a carbide precipitation map using time and temperature during aging of quenched 2.25Cr-1Mo-0.15C steel by the examination of precipitates in the transmission electron microscope (TEM). Since that time, analogous studies using higher resolution analytical TEM techniques have conformed this gradual transformation of carbides towards the stable M6C. In this study, a similar alloy was quenched and the thermodynamic response during tensile strain rate change tests were correlated with the aging time at specific temperatures. The strain rate sensitivity tests performed at 200C showed a solute drag contribution which could be attributed increasing when the M6C regime was approached. The calibration and sensitivity of this technique will be illustrated.

3:45 pm

EFFECT OF SPECIMEN THICKNESS ON NEAR-THRESHOLD FATIGUE CRACK PROPAGATION OF SA106 GR.C NUCLEAR MAIN STEAM LINE PIPE WELD JOINTS: E.S. 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

Characteristics of near-threshold fatigue crack propagation have been examined in SA106 Gr.C nuclear main steam line pipe and its weld to evaluate the effect of specimen thickness. Tests were performed for load ratios of 0.1 and 0.5 at room temperature in ambient air. Near-threshold fatigue crack growth rates decreased and threshold values increased with increasing specimen thickness. The proposed concept of stress state and microstructure influence on crack closure explains the effect of specimen thickness on near-threshold fatigue crack propagation behavior.

4:05 pm

POST-IRRADIATION ANNEALING OF MICROSTRUCTURAL AND MICROCHEMICAL CHANGES IN PROTON IRRADIATED 304L STAINLESS STEEL: J.T. Busby, J. Gan, G.S. Was, Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109-2104

Abstract not available.