Influence of the Titanium Carbide Content in a Filler Powder Wire Charge on the Structure of the Weld Metal

The changes in the microstructure and hardness of the metal deposited with a powder wire 2 mm in diameter with various titanium carbide contents in a charge (from 10 to 100 wt %) during their surfacing by an unconsumable electrode are studied. In all cases, titanium carbide is shown to be conserved only partially and to be nonuniformly distributed over entire welding bath volume. TiC partially dissolves in the welding bath melt and then leads to the formation of fine (3–11 μm) titanium carbide phases in the eutectic. An increase in the titanium carbide content in the charge composition leads to a change in the form of fine carbides and also their sizes. The hardness of the weld metal is found to change insignificantly as the TiC content increases from 10 to 45%; however, in the case of surfacing by a wire with 100% TiC, the hardness decreases due to the absence of alloying elements in the powder wire charge. The introduction of titanium carbide through a filler flux-cored powder wire does not allow one to significantly decrease the degree of dissolving the carbide in the weld metal as compared to the introduction of titanium carbide with an electrode material.