Barium inoculation
Barium inoculation promotes graphite precipitation in cast iron and reduces hard, white microstructure. This improves toughness and formability.
Physico-Chemical Mechanism of Action
Barium inoculation acts as an effective nucleation agent in the molten pool. It promotes the formation of graphite by reducing carbon content and refining the grain. This prevents the formation of hard, white microstructure constituents like martensite or troostite.
Metallurgical Relevance & Risks in Welding
Sufficient barium inoculation ensures a soft, tough, and formable solidification. This reduces susceptibility to cracking and improves the formability of cast iron. With too little or no inoculation, a harder microstructure can form, which may lead to hot cracking.
Shop Practice & Action Instructions
For successful barium inoculation, it is important to respect the correct dosage point and temperature during the melting process. A typical dosage is about 0.1 to 0.3% barium-containing material in the melt. The inoculation time should be between 5 and 20 seconds, depending on the desired solidification structure. Too short or too long times can prevent achieving the desired microstructure.