Zener pinning of grain growth
Zener grain growth describes how grains in metals enlarge during cooling. This can alter the mechanical properties.
Physical-Chemical Mechanism of Action
During cooling of metals, grain boundaries can move and grain growth occurs. This process is named after Zener, who studied the importance of these phenomena.
Metallurgical Relevance & Welding Risks
If cooling is too fast, grain growth can be interrupted, resulting in fine grains, which impairs toughness. If cooling is too slow, grain growth can be promoted, leading to large grain size, which increases hardness and reduces fracture strength.
Workshop Practice & Action Instructions
To achieve optimal grain growth, cooling should be controlled. This can be done by selecting the appropriate welding process and proper cooling strategy. For steels with high zinc or nickel content, it is especially important that grain growth is not interrupted to ensure stable mechanical properties.