Journal of the Korean Society of Manufacturing Process Engineers (한국기계가공학회지)

The Korean Society of Manufacturing Process Engineers (한국기계가공학회)
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Effects of Long-term Artificial-Aging on the Hardness Variation of Dissimilar Metal Weldments

이종금속 용접부의 경도변화에 대한 장시간 인공열화의 영향

  • Kim, Chung-Seok (Dep. of Materials Science and Engineering, Chosun UNIV.)
  • 김정석 (조선대학교 재료공학과)
  • Received : 2018.10.23
  • Accepted : 2018.11.14
  • Published : 2019.01.31
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Abstract

This study investigates the effects of long-term artificial-aging on hardness variation in the dissimilar metal weldments for nuclear power plant facilities. These dissimilar welds are inevitably required to join the components in nozzle parts of pressurized vessels, such as austenitic stainless steels and ferritic steels. A artificial thermal aging was conducted in an electrical furnace to simulate material degradation at high temperatures. The test materials were held at the temperature of $600^{\circ}C$ for 10000 hours and interrupted at various levels of degraded specimens. The degradation of hardness is a well-known phenomenon resulting from long-term aging or high-temperature degradation of structural materials. In this study, the variation of hardness at each position was different, and complicated in relation to microstructures such as twins, grains, precipitates, phase transformations, and residual stresses in dissimilar weldments. We discussed the variation of hardness in terms of microstructural changes during long-term aging.

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References

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