Lamellar graphite formation

Physical-Chemical Mechanism of Action

In gray cast iron, graphite crystallizes as flake- or strip-shaped structures, which create sharp-edged notches in the metal matrix.

Metallurgical Relevance & Welding Risks

These sharp edges can lead to cracks and hot cracking. The tensile strength of the steel drops because the graphite notches impede the movement of atomic currents.

Workshop Practice & Action Guidelines

To avoid lamellar graphite formation, ensure sufficient hardness and a good structure in the weld. This requires correct selection of steel with an appropriate carbon content (approx. 0.3 to 0.5 %) and careful control of welding parameters like temperature and time.