Small punch test evaluation of intergranular embrittlement of an alloy steel
The ductile-brittle transition temperature in steel is commonly determined using Charpy V-notch impact specimens as specified by ASTM E23-81. In some specific cases, however, the use of this standardized test specimen may be impractical, if not impossible. For instance, it is well known that ferritic steels show a substantial degradation of the mechanical properties after long time exposure to an irradiation environment. Because of the increase in strength and the reduction in ductility due to neutron irradiation, the Charpy V-notch transition temperature is raised causing concern from a safety point of view. To study these radiation effects, a test specimen much smaller than the standard Charpy V-notch specimen would be extremely desirable for two reasons. First, to study neutron damage small specimens take less space within a reactor. Secondly, the damage achieved in simulation experiments, such as proton or electron accelerators, is limited to small penetration depths. Several efforts on the development of such a small test specimen, similar to that used to determine the ductility of sheet metal, as recommended by ASTM E643-78, have been described in the literature. The paper reports on correlations between small punch (SP) and Charpy V-notch (CVN) test results obtained on temper-embrittled NiCr steel. The ductile-brittle transition temperature (DBTT) with intergranular embrittlement being induced by grain boundary segregation of specific impurities was determined. The relation between test results discussed in terms of the micromechanisms of intergranular cracking. It is suggested that in radiation embrittlement investigations similar correlations may be obtained.
- Research Organization:
- Ames Laboratory, Iowa State University, Ames, Iowa
- OSTI ID:
- 6461828
- Journal Information:
- Scr. Metall.; (United States), Vol. 17:12
- Country of Publication:
- United States
- Language:
- English
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Ductile-brittle transition temperature measurement of temper embrittled Ni-Cr steels by means of small punch tests
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Related Subjects
NICKEL-CHROMIUM STEELS
CHARPY TEST
CRACK PROPAGATION
DAMAGING NEUTRON FLUENCE
DUCTILE-BRITTLE TRANSITIONS
EMBRITTLEMENT
PHYSICAL RADIATION EFFECTS
CORRELATIONS
GRAIN BOUNDARIES
IMPURITIES
IRRADIATION
NEUTRON FLUX
SHEETS
TRANSITION TEMPERATURE
ALLOYS
CHROMIUM ALLOYS
CRYSTAL STRUCTURE
DESTRUCTIVE TESTING
IMPACT TESTS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS TESTING
MECHANICAL TESTS
MICROSTRUCTURE
NEUTRON FLUENCE
NICKEL ALLOYS
NICKEL STEELS
PHYSICAL PROPERTIES
RADIATION EFFECTS
RADIATION FLUX
STEELS
TESTING
THERMODYNAMIC PROPERTIES
360106* - Metals & Alloys- Radiation Effects