Quantitative characterisation of weld simulated structures in duplex stainless steel SAF 2205
Swedish Institute for Metals Research, Drottning Kristinas väg 48, S-114 28 Stockholm, Sweden
Professor in Applied Materials Technology, Royal Institute of Technology, S-100 44 Stockholm, Sweden
Abstract
Microstructures of SAF 2205 type steel after weld simulation were investigated using the automatic image analysis system. Conventional etching produced weak contrast between phases. After modification of the colour etching method, a clear distinction between the austenite and ferrite phases was obtained. Microstructure was quantitatively characterised by the area fraction and the width of austenite at ferrite grain boundaries, also by mean free distance between the austenite islands distributed in the ferrite matrix. The measured structural parameters are related to Charpy-V impact energy data. In particular the width of the austenite islands located at the ferrite grain boundaries had a significant influence on the impact energy.