Atom Probe Microanalysis of Weld Metal in a Submerged Arc Welded Chromium-Molybdenum Steel

Abstract

Resum6 -Un acier 2.25Cr -lMo, soude sous flux, est Cte etudie par microscopie electronique, microscopie ionique B emission de champ et la sonde B atomes. La microstructure bainite de l'acier soude consiste en ferrite et martensite. En traitment thermique B 690°C martensite se transforme en ferrite et cementite, et carbures (Cr,Mo)nC en forme d'aiguille se forment. Avec une reduction de la densite de dislocations, cela a result6 d'une amelioration de la tenacite de l'acier.Abstract -A submerged arc welded 2.25Cr -1Mo steel has been investigated using electron microscopy and atom probe field ion microscopy. The bainitic microstructure of the as-welded steel consisted of ferrite and martensite. During heat treatment at 690°C the martensite transformed to ferrite and cementite and needle-shaped (C~,MO)~C carbides precipitated. Together with a substantial decrease in dislocation density, this resulted in an improvement of the toughness.

In situ observation and electron backscattered diffraction analysis of granular bainite in simulated heat-affected zone of high-strength low-alloy steel

“…In fact, granular bainite (GB) may form in HAZ of filling passes according to our study which has been thought to deteriorate welding joint substantially [10, 11]. GB is an intermediate transformation product of austenite and consists of thin long α-phase laths that joined into coarse bundles with respect to the relatively equiaxed shape and carbon-enriched islands [12, 13].…”