Hot cracking susceptibility
Hot cracking susceptibility is the tendency of steels to crack during cooling due to residual liquid films at the grain boundaries. These films can form due to excessively high melting temperatures or insufficient deoxidation.
Physical-Chemical Action Mechanism
Hot cracking susceptibility occurs when residual liquid films remain at the grain boundaries of the steel. These films can form during welding due to excessively high temperatures or insufficient deoxidation. They prevent complete solidification and can lead to local stress concentrations that trigger cracks.
Metallurgical Relevance & Risks in Welding
High hot cracking susceptibility increases the risk of cracks in the weld. This can cause failure under mechanical stress and endanger the safety of the component. It is especially critical in highly stressed applications or steels with high hot cracking susceptibility.
Workshop Practice & Handling Instructions
To minimize hot cracking susceptibility, the following measures should be taken:
• Use a suitable deoxidizer (e.g., silicon) in the weld pool.
• Ensure that the melting temperature does not exceed the maximum allowable value.
• Cool the weld in a controlled manner and avoid too rapid cooling.
• Regularly inspect grain boundaries for residual liquid films and remove them if necessary.