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 (γ) and ferrite (δ) 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 δ was observed to be higher than that of γ. This implies a stronger texture for δ (a strong rotated cube texture 001 110 along with minor α-fibre rolling direction , RD / / 110 and γ-fibre normal direction , ND / / 111 ) than γ [Brass, Cu, Goss and S texture components ( 110 112 , 112 111 , 110 001 and 123 634 , respectively)] in the annealed state (BMZ). γ/δ 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 δ than γ 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. [ABSTRACT FROM AUTHOR]