ISSN: 0090-3973
Page Count: 9

Crack-Arrest Testing of Irradiated Nuclear Reactor Pressure Vessel Steels at the Oak Ridge National Laboratory

Iskander, SK
Metals and Ceramics Division,TN,

Milella, PP
Agenzia Nazionale per la Protezione dell'Ambiente (ANPA),

Pini, A
Agenzia Nazionale per la Protezione dell'Ambiente (ANPA),

Manneschmidt, ET
Metals and Ceramics Division,TN,

(Received 5 June 1997; accepted 2 July 1998)

Abstract

Crack-arrest testing of nuclear pressure vessel steels has been conducted at Oak Ridge National Laboratory for many years. Four methods have been used to initiate fast-running cracks in crackarrest specimens: (1) the deposition of a brittle weld bead using hardfacing weld electrodes, (2) water quenching a chevron crack tip, (3) quenching the crack tip by discharging a large current into the crack tip region, and (4) the use of duplex specimens. A problem often encountered with Methods 1 and 4 is the control of the width of the heat-affected zone (HAZ). The HAZ is generally tough and can arrest crack propagation before it has run into the test section. Irradiated crack-arrest specimens were prepared using Methods 1, 3, and 4. Method 1 was the most successful, while Method 4 was the least successful. This paper will discuss some of the reasons for the success, or lack of, as well as the results of testing both a high-copper weldment and a low-copper forging in terms of the shift and shape of the K^a toughness curve compared to the Charpy V-notch shift. The present ASTM Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, K^Ia, of Ferritic Steels (E 1221-88) validity criteria will also be discussed in light of the results.

Keywords:
crack-arrest toughness, shift of toughness curve, American Society of Mechanical Engineers (ASME) KIR curve, ASME KIa curve, pressure vessel steels, reference temperature, RTNDT, effect of neutron irradiation on crack-arrest toughness

Paper ID: JTE12158J
DOI: 10.1520/JTE12158J
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