Flow curve
The flow curve shows the relationship between stress and strain during a forming process. It describes how the material work-hardens.
Physical-chemical mechanism of action
The flow curve is a graphical representation of stress (in N/mm²) versus plastic strain (in %). It shows how high the stress must be to plasticize and work-harden the material. With increasing strain, the required stress rises, reflecting the material's hardening behavior.
Metallurgical relevance & risks during welding
The flow curve is crucial for selecting the right forming technique and parameters. Too high stress can lead to defects and cracks, while too low stress results in insufficient hardening and poorer mechanical properties.
Workshop practice & instructions
When welding, it is important to know the flow curve of the steel being used. For optimal forming, set the stress so that it lies within the so-called "flowing zone." This means the stress is neither too high (to avoid cracks) nor too low (to ensure sufficient hardening). For steels with a high flow curve, careful stress control is essential to improve the mechanical properties of the weld.