Austenite grain growth
Austenite grain growth is the increase in crystal size in austenite at elevated temperatures. It can be prevented by microalloying elements such as niobium or titanium.
Physical-Chemical Mechanism
Austenite grain growth occurs when austenite at elevated temperatures is in contact with dissolved microalloying elements. These elements can limit the crystal size and prevent it from growing too large.
Metallurgical Relevance & Welding Risks
Uncontrolled austenite grain growth can lead to coarsening of the grain in the weld. This can impair the toughness and mechanical behavior of the steel, leading to cracks or failure.
Workshop Practice & Instructions
To prevent austenite grain growth, microalloying elements such as niobium or titanium should be added to the weld pool. The temperature during the cooling process should be carefully controlled to limit the growth of crystal size.