Insights into the Microstructure and Texture Evolution Using Electron Backscattered Diffraction and Thermal Stability of Low Mn Fe-25Cr-6.5Ni-3.5Mo Alloy

The effect of weld chemistry (two types of electrodes (E2594 and E2595)) on the microstructure and texture development using electron back scattered diffraction and thermal stability during shielded metal arc welding of alloy 2507 have been studied. Base metal showed alternate bands of austenite (?) and ferrite (8) in almost equal fractions. Weldments were mainly comprised of 3 zones, namely base metal zone (BMZ), heat affected zone (HAZ), and weld metal zone (WMZ). After welding, ferritic solidification mode was found with diverse morphologies of austenite viz. grain boundary austenite, Widmanstatten austenite, and intergranular austenite and a decrease in the fraction of austenite in WMZ and HAZ. The texture intensity of 8 was observed to be higher than that of ?. This implies a stronger texture for d (a strong rotated cube texture ({001}(110)) along with minor a-fibre (rolling direction, RD//(110)) and ?-fibre (normal direction, ND//(111))) than ? [Brass, Cu, Goss and S texture components ({110}(112), {112}(111), {110}(001) and {123}(634), respectively)] in the annealed state (BMZ). ?/d grains showed the Kurdjumov-Sachs (K-S) orientation relationship. Kernel average misorientation (KAM) graphs/maps showed no significant change in BMZ but a substantial decrease in KAM values in d than ? for both weldments. The peak temperature attained was sufficiently higher than the melting temperature of base/filler metal suggesting the proper melting and diffusion of molten metal throughout the thickness. The size of the melt pool widened for E2594 and was relatively small for E2595.

Automated summary

The effect of weld chemistry on the microstructure and texture development during shielded metal arc welding of alloy 2507 has been studied. The study found that the weldments were mainly comprised of three zones: the base metal zone, heat affected zone, and weld metal zone. The fraction of austenite in the weld metal zone and heat affected zone decreased after welding. The study also observed different morphologies of austenite and a stronger texture for ferrite compared to austenite in the annealed base metal.