Phase Boundary
The phase boundary interface is the boundary area between two different material phases, such as metal and melt. Here, physical and chemical properties change abruptly.
Physical-Chemical Mechanism of Action
The interface forms during the transition from one state to another, such as when a metal melts or cools. At this boundary, atoms and molecules change their structure and properties.
Metallurgical Relevance & Risks in Welding
The interface plays a key role in the development of cracks and hardness problems in weld areas. Cooling too fast can lead to glass-hard martensite, making the weld prone to cracking. Cooling too slow coarsens the grain and reduces the steel's toughness.
Workshop Practice & Instructions
To ensure a safe weld, it's important to control the interface. This requires correct heat treatment and a suitable cooling pattern. For steels with high carbon content, the critical temperature window (t8/5) should be between 5 and 25 seconds to ensure adequate toughness.