Effect of carbonate in electrode coating on the microstructure and mechanical properties of weld

Abstract

In this study, various additions of carbonates, MgCO(3), Na(2)CO(3), K(2)CO(3) and BaCO(3), respectively, were added in electrode coating to investigate microstructure and mechanical properties of weld metal. The results showed that alpha-Fe phase with bcc structure existed in each weld metal. The microstructure included of the primary ferrite (i.e. grain boundary ferrite and intragranular polygonal ferrite), the ferrite with second phase and acicular ferrite. When the addition of MgCO(3) and Na(2)CO(3) increased, the content of primary ferrite increased and acicular ferrite decreased. On the other hand, the addition Of K(2)CO(3) and BaCO(3) promoted the content of primary ferrite reducing and acicular ferrite increasing. So far as mechanical properties were concerned, the addition of carbonates affected hardness, tensile strength and toughness of weld metal. MgCO(3) and Na(2)CO(3) diminished the mechanical properties due to the microstructure became coarser. Oppositely, K(2)CO(3) and BaCO(3) improved mechanical properties due to the microstructure became finer. (C) 2008 Elsevier B.V. All rights reserved.