Effect of welding conditions on transformation and properties of heat-affected zones in LWR (light-water reactor) vessel steels

Technical Report · Thu Nov 01 00:00:00 EST 1990

DOI:https://doi.org/10.2172/6337784· OSTI ID:6337784

Lundin, C D; Mohammed, S ^[1]

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1. Tennessee Univ., Knoxville, TN (USA). Welding Research and Engineering

The continuous cooling transformation behavior (CCT) and isothermal transformation (IT) behavior were determined for SA-508 and SA-533 materials for conditions pertaining to standard heat treatment and for the coarse-grained region of the heat-affected zone (HAZ). The resulting diagrams help to select welding conditions that produce the most favorable microconstituent for the development of optimum postweld heat treatment (PWHT) toughness levels. In the case of SA-508 and SA-533, martensite responds more favorably to PWHT than does bainite. Bainite is to be avoided for the optimum toughness characteristics of the HAZ. The reheat cracking tendency for both steels was evaluated by metallographic studies of simulated HAZ structures subjected to PWHT cycles and simultaneous restraint. Both SA-533, Grade B, Class 1, and SA-508, Class 2, cracked intergranularly. The stress rupture parameter (the product of the stress for a rupture life of 10 min and the corresponding reduction of area) calculated for both steels showed that SA-508, Class 2, was more susceptible to reheat cracking than SA-533, Grade B, Class 1. Cold cracking tests (Battelle Test and University of Tennessee modified hydrogen susceptibility test) indicated that a higher preheat temperature is required for SA-508, Class 2, to avoid cracking than is required for SA-533, Grade B, Class 1. Further, the Hydrogen Susceptibility Test showed that SA-508, Class 2, is more susceptible to hydrogen embrittlement than is SA-533, Grade B, Class 1.

• Research Organization: US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Div. of Engineering; Tennessee Univ., Knoxville, TN (USA). Welding Research and Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USNRC
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6337784
• Report Number(s): NUREG/CR-3873; ORNL/Sub-78-7637/1; ON: TI91004247; TRN: 90-036969
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
BWR TYPE REACTORS
PRESSURE VESSELS
WELDED JOINTS
PWR TYPE REACTORS
STEELS
MECHANICAL PROPERTIES
CHARPY TEST
CRACKS
EMBRITTLEMENT
HEAT TREATMENTS
HYDROGEN
ISOTHERMAL PROCESSES
MICROSTRUCTURE
STANDARDS
STEEL-ASTM-A508
STEEL-ASTM-A533
STRESSES
WELDING
ALLOYS
CONTAINERS
CRYSTAL STRUCTURE
DESTRUCTIVE TESTING
ELEMENTS
FABRICATION
IMPACT TESTS
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
LOW ALLOY STEELS
MATERIALS TESTING
MECHANICAL TESTS
NONMETALS
REACTORS
TESTING
WATER COOLED REACTORS
WATER MODERATED REACTORS
360103* - Metals & Alloys- Mechanical Properties
210100 - Power Reactors
Nonbreeding
Light-Water Moderated
Boiling Water Cooled
210200 - Power Reactors
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