Steadite
Steadite is a ternary eutectic in phosphoric cast iron, consisting of austenite, iron phosphide, and cementite. It forms during the solidification of the remaining melt.
Physicochemical Mechanism of Action
Steadite forms through the condensation of austenite, iron phosphide, and cementite in phosphorized cast iron. This process occurs during residual melt solidification when the iron content is below 4.3%.
Metallurgical Relevance & Risks in Welding
The formation of steadite can lead to difficulties in welding. It can result in poor weld joints and increased stress buildup, which can cause cracks and distortion. Additionally, it can lead to increased weld toughness, which is difficult to machine.
Workshop Practice & Instructions
To avoid steadite, the iron content of the cast iron should be kept above 4.3%. If the iron content is low, adding carbon or nickel can help suppress the formation of steadite. Welding time and temperature should be precisely controlled to achieve a homogeneous joint.