Liquidus temperature line
The liquidus temperature line is the point in a phase diagram above which an alloy is completely liquid. It indicates when solidification starts.
Physical-chemical mechanism of action
The liquidus temperature line in a phase diagram gives the temperature above which all components of an alloy are in the liquid state. This line separates the liquid region from the solid region.
Metallurgical relevance & welding risks
The liquidus temperature line is critical for choosing the right welding process and shielding gas. If temperatures are too low, you can get incomplete fusion or too much cooling, leading to cracks and poor toughness in the weld. If temperatures are too high, the material can melt excessively, losing strength and mechanical properties.
Workshop practice & instructions
To stay on the right side of the liquidus line, you need to control welding parameters like temperature and time precisely. With highly alloyed steels (e.g., HSS), it's especially important to keep the melting temperature above the line to get a uniform weld. With lower alloys, keep the temperature below the line to avoid cracks and distortion.