Causes And Solutions Of Cracks in Titanium Plates

Cracks are a common defect in titanium plate welding. Titanium weld cracks are cold cracks, mainly caused by hydrogen in the weld. The main sources of hydrogen include moisture and oil in the plate and welding wire. Environmental humidity is the main cause of hydrogenation in the weld.
Under the action of high temperature during welding, a large amount of hydrogen is dissolved in the molten pool. During the cooling and solidification process of the weld, hydrogen easily escapes due to the rapid decrease in solubility. If the weld cools too quickly, the hydrogen will not have time to escape and remain in the weld, which will make the hydrogen in the weld supersaturated, so the hydrogen will try its best to diffuse and promote further embrittlement in this area.
If there is a notch effect in this part and the hydrogen concentration is high enough, cracks may occur. Especially during winter construction, the ambient temperature is low and water vapor adheres to the titanium plate, creating conditions for hydrogenation of the weld. Because the titanium plate is too thin (1.2mm), the steel plate is relatively "warm" and the temperature rises slowly. The corresponding titanium composite layer weld seam cools too fast. During the cooling process, the residual hydrogen in the weld seam has no time to escape. It exists in the form of super saturation in the weld, eventually leading to the appearance of cracks.
Therefore, during the welding process of titanium steel composite plates, the surfaces of the base metal and welding wire must be carefully cleaned, and the ambient temperature must be maintained at not lower than 5°C. During winter construction, flames should be used to preheat the base steel surface, firstly to remove moisture around the weld; secondly, to increase the temperature of the weldment and reduce the cooling rate of the weld.