Eutectic Carbide Morphology
The geometric appearance of carbides solidifying directly from the melt during the eutectic reaction. It shapes the wear behavior of high-alloy cast iron materials.
When welding hardfacing, you often see these eutectic carbides – they are hard, brittle microstructural constituents that form in the melt. When the melt solidifies, these carbides precipitate in a typical, often needle-like or fine structure. The size and distribution of these carbides determine wear resistance and crack behavior. Fine, evenly distributed carbides make the material tough and hard, while coarse or clustered carbides make it brittle and prone to cracking. During welding, you have to control the cooling. If you cool too fast, fine, hard microstructures form, but also stresses. If you cool too slowly, the carbides grow coarse and the material becomes brittle. The right cooling depends on the base material – you have to choose the heat input and interpass temperature so that the carbides remain fine, but no stress cracks occur.