Core-shell microstructure
Almond-core structure is an inhomogeneous microstructure with a continuous change in chemical composition and phase distribution from the core to the edge.
Physical-Chemical Mechanism of Action
Mandelkern structure forms due to different cooling rates within a weld component. The core cools slower than the edge, leading to a continuous change in chemical composition and phase distribution.
Metallurgical Relevance & Risks in Welding
Mandelkern structure can lead to increased toughness and improved mechanical properties when properly controlled. However, uncontrolled cooling can cause uneven hardness distribution and possible cracks.
Workshop Practice & Instructions
To create Mandelkern structure, it's important to keep the cooling rate controlled. This can be achieved by choosing the right shielding gas and proper cooling techniques. A typical goal is consistent hardness with a core that has about 20-30 HRC.