Primary solidification structure
The primary solidification structure forms immediately after the melt solidifies and determines mechanical properties such as strength and toughness.
Physical-Chemical Mechanism of Action
After the melt enters the liquid state, it begins to cool. During this process, the metal crystallizes and forms the primary solidification structure. This structure consists of various crystal phases whose structure and arrangement determine the material's mechanical properties.
Metallurgical Relevance & Welding Risks
The primary solidification structure has a major impact on the weld's mechanical properties. A fine, homogeneous structure provides high toughness and strength, while a coarse or heterogeneous structure can lead to lower stress levels and potential cracking. Improper cooling steps can alter the structure and impair weld service life.
Workshop Practice & Action Guidelines
To achieve a good primary solidification structure, it is crucial to perform the cooling step in a controlled and uniform manner. This can be achieved by selecting the right welding process (e.g., TIG welding for high-quality steels) and correctly using shielding gases. Cooling steps should be designed to keep the metal within a critical temperature range to ensure a homogeneous structure.