Hull Weld Metal Diagram
The Weld-Metal-Diagram according to Hull shows the relationship between the degree of melting and transformation time in stainless steel welds. It helps predict the microstructure and mechanical properties.
Physical-chemical mechanism of action
The Weld-Metal Diagram according to Hull visualizes how the microstructure of stainless steels changes when they are welded. It takes into account the melting ratio (percentage of melted material) and the transformation time (time in seconds during which the material is transformed).
Metallurgical relevance & risks in welding
The diagram is crucial for optimizing welding parameters. An incorrect ratio between melting ratio and transformation time can lead to undesirable microstructures, such as too much martensite, which increases hardness and reduces toughness. This can lead to cracks and hot cracks in the weld pool.
Workshop practice & instructions
To use the Weld-Metal Diagram according to Hull effectively, the following steps should be observed:
1. Determine the desired melting ratio and transformation time for the stainless steel weld.
2. Adjust the welding parameters (e.g., voltage, speed) to achieve these values.
3. Continuously monitor the temperature and the process to ensure that the material stays in the optimal zone.