Glass transition temperature of amorphous phases
The glass transition temperature of amorphous phases is the range where an undercooled melt transitions from an elastic state to a brittle, glassy state without crystallization.
Physical-Chemical Mechanism of Action
The glass transition temperature of amorphous phases describes the temperature range in which a liquid metal composition is undercooled and changes from an elastic state to a brittle, glassy state. This happens without the formation of a crystalline structure.
Metallurgical Relevance & Risks in Welding
If cooling is too fast, a weld can turn into an amorphous state, leading to brittle and tough deformability. This increases susceptibility to cracking and changes the mechanical behavior of the weld. However, too slow a cooling process can lead to crystallization, causing other metallurgical defects.
Workshop Practice & Instructions
To control the glass transition temperature of amorphous phases, it is important to precisely set the cooling position and rate. For steels with high silicon or carbon content, careful control of cooling measures is needed to achieve an optimal crystallization state. The t8/5 time should be between 5 and 25 seconds to ensure a balanced microstructure.