Determination of Mo-Rich Laves-Phase in Weld Metals of a Creep-Resistant 9% Cr-Steel Using Light Optical Microscopy

Creep-resistant 9% Cr-steels feature different phases in their weld metal microstructure; especially after creep-rupture testing. Laves-Phase in such alloying concepts is widely studied, but there is still a need for a simple identification technique utilizing light optical microscopy. The Lichtenegger–Bloech color tint etchant was utilized to contrast the weld metals microstructure in as-welded condition, after post-weld heat treatment and creep-rupture tested. Proof of the presence of Laves-Phase after creep-rupture tests in the weld metal of a 9% Cr-steel GX13CrMoCoVNbNB9-2-1 (CB2) was performed using Lichtenegger–Bloech and light optical microscopy. To validate Laves-Phase within the analyzed microstructure, scanning electron microscopy and energy dispersive x-ray spectroscopy were performed. For a thorough analysis, phase analysis was done in selected regions of interest. The results show that the Laves-Phase in this type of steel can be easily contrasted and quantified at comparatively low lateral resolutions by Lichtenegger–Bloech, with no further need of analysis required.