Grain-inhibiting effect
Grain growth limiting effect holds back austenite grain growth at high temperature at phase boundaries, thus preventing the formation of large grains and improving mechanical properties.
Physical-Chemical Mechanism of Action
Grain growth limiting elements such as niobium or titanium bind to phase boundaries in austenite. They form a kind of protective layer that prevents the growth of new grains and also thermally arrests the austenite grain growth.
Metallurgical Relevance & Risks in Welding
Without grain growth limiting elements, austenite grain growth can proceed uncontrollably at high temperature, leading to large grain formation and thus poor mechanical properties. This can particularly affect toughness and resistance of the material.
Workshop Practice & Action Guidelines
To optimally utilize the grain growth limiting effect, it is important to ensure that the weld pool is kept stable and the correct amount of grain growth limiting elements is maintained. When selecting alloying materials, those with high niobium or titanium content should be preferred when high toughness and resistance are required.