Measurement of martensitic transformation of 9% Ni steel during welding using ESPI system

Susumu Meguro, Satoru Kobayashi, Terumi Nakamura, Kaneaki Tsuzaki

Research output: Contribution to journalArticle

Abstract

Displacement and strain during welding are important parameters for evaluation of weld joint. But in-situ measurement of these values needs non-conductive method because weld joint reaches to high temperature. So we applied electronic speckle pattern interferrometry (ESPI) system to measurement of displacement and strain during gas-tungsten-arc (GTA) welding of 9%Ni steel. This system detects interference of refected laser illumination from weld joint surface. The change of interference depends on displacement of weld joint surface. ESPI measurement starts simultaneously with GTA heating, and continues during cooling after heating fnished. ESPI system reveals behavior of two dimensional displacement distribution during welding and martensitic transformation in weld joint. Quantitated displacement record of certain point in GTA heating area shows detail of martensitic transformation. Martensite start temperature (Ms) analyzed by ESPI result shows higher value than conventional value measured by uniform heating and cooling process. This result shows stress-assisted martensitic transformation occurred in this area, because tensile stress is forced after solidifcation of weld metal at GTA heating area. Quantitated value of Ms raising corresponds to additional chemical driving force for martensitic transformation. This driving force is estimated using free energy calculation. In the case of this study, this driving force is added as tensile stress at GTA heating area and ESPI result is useful to estimate the value of stress.

Original languageEnglish
Pages (from-to)632-638
Number of pages7
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume100
Issue number5
DOIs
Publication statusPublished - 2014

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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