Combined Microalloying
Combined microalloying: Simultaneous addition of small amounts of niobium, titanium, and vanadium to control the microstructure and strength.
Physical-Chemical Mechanism of Action
Niobium, titanium, and vanadium are microalloying elements. They react with the steel and alter the grain structure. This microalloying affects the microstructure and increases the strength of the material.
Metallurgical Relevance & Risks in Welding
The correct microalloying addition improves the mechanical properties of the weld. However, too little or too much can lead to unwanted microstructural changes, which can reduce toughness and increase the risk of cracking.
Workshop Practice & Instructions
For optimal combined microalloying, use the following amounts: Niobium 0.1-0.3%, Titanium 0.05-0.15%, and Vanadium 0.2-0.4%. The additives must be precisely worked into the weld pool preparation. Too rapid cooling can make the structure too hard, while too slow cooling makes it too soft.