Titanium alloy welding cracks and preventive measures

Welding cracks are common quality defects in titanium alloy welding. Because titanium alloys contain fewer impurities such as sulfur, phosphorus, and carbon, low-melting eutectics are generally not common in grain boundaries, and the effective crystallization temperature range is narrow. The shrinkage is small during the process of seam solidification, so hot cracks rarely occur during welding. If the quality of the base metal and the welding wire does not meet the standard requirements, if there are quality defects, and there are harmful substances in the interlayer, hot cracks may occur. Therefore, you should pay attention to the quality of the welding wire when welding. And do a good job in the protection of harmful substances and strengthen the heat treatment after butt welding, which can effectively avoid the occurrence of thermal cracks.

Delayed cracks may appear in the heat-affected zone during the welding of titanium alloys, and such cracks generally appear within a period of time after welding. In order to prevent the occurrence of delayed cracks, the hydrogen content of the welded joints should be reduced as much as possible. You can choose based materials and welding wires with less hydrogen content, and clean up before welding, and eliminate residual stress after welding. Generally, titanium hydride does not appear in titanium alloys with normal hydrogen content, so the probability of cracks in the weld is also very small. However, when using thick-plate α+β Grade 5 Ti-6Al-4V Titanium Plate for multi-layer welding, the use of industrial pure titanium as a filler material will cause the appearance of titanium hydride, thereby inducing hydrogen embrittlement.