Titanium plate welding always cracking? Hydrogen is the "culprit"! 3 tricks to solve the problem

In high-tech fields such as aerospace and medical care, titanium plates and titanium-steel composite plates have become indispensable key materials due to their high strength, light weight and excellent corrosion resistance. However, in practical applications, the welding process often fails - cracks occur frequently, not only affecting product quality but also posing safety risks to engineering projects. Today, we will delve into the causes of titanium plate welding cracks and offer practical solutions to help you overcome this technical bottleneck!

I. Uncovering the Culprits Behind Cracks: Three Key Factors Not to Be Ignored
Hydrogen: The Culprit of Cold Cracking
Hydrogen is the core cause of cold cracks in titanium welds. It mainly "invades" the welding process through two channels: on the one hand, moisture and oil on the plates and welding wires themselves will release hydrogen during welding; on the other hand, environmental humidity is an accomplice, which can significantly increase the hydrogen content in the welds.

During welding, high temperatures cause a large amount of hydrogen to dissolve into the molten pool. However, when the weld seam cools and solidifies, the solubility of hydrogen drops sharply. Hydrogen that should have escaped will be trapped in the weld seam if the cooling rate is too fast, leading to a supersaturated state of hydrogen. These "nowhere to go" hydrogen atoms will continuously diffuse, making the surrounding area fragile and laying a "time bomb" for crack formation.

2. The notch effect + high hydrogen concentration: Double threats amplify risks
When there is a notch in the weld seam, local stress concentration occurs; and when the hydrogen concentration reaches a certain level, it will reduce the toughness of the material. These two factors "join hands", causing the probability of crack occurrence to rise sharply, just like adding insult to injury to the already fragile weld seam.

3. Winter Construction: Special Challenges Brought by Low Temperatures
In winter, the low temperature makes water vapor prone to adhere to the surface of titanium plates, creating favorable conditions for hydrogenation of the weld seam. Especially for thin titanium plates with a thickness of only 1.2mm, due to their "slow heating" characteristic - slow temperature rise, the cooling rate of the titanium composite layer weld seam is too fast. During this rapid cooling process, the residual hydrogen in the weld seam has no time to escape and can only remain in a supersaturated state in the weld seam, eventually causing cracks.

II. Solving the Problem of Cracks: 3 Practical Methods, Please Take Note
1. Surface cleaning: Eliminating the "invasion" of hydrogen from the source
Before welding, it is essential to carefully clean the surface of the base material and the welding wire. This is a crucial step to reduce the source of hydrogen. Mechanical cleaning methods such as grinding or chemical cleaning can be used to thoroughly remove surface moisture, oil, and other impurities, keeping the base material and welding wire clean and dry, and laying a good foundation for subsequent welding.

2. Environmental Control: Creating a Suitable "Microclimate" for Welding
The ambient temperature for welding must not be lower than 5℃, which is a crucial prerequisite for preventing cracks. During winter construction when the ambient temperature is low, the base steel surface can be preheated by flame to address the issue: this not only removes moisture around the weld seam and reduces the source of hydrogen, but also raises the temperature of the weldment, slows down the cooling rate of the weld seam, allowing hydrogen sufficient time to escape and avoiding over-saturation and residue.

3. Process Optimization: Reducing Risks through Parameter Control
Reasonably adjusting welding parameters is crucial for preventing cracks. For instance, appropriately regulating welding current, voltage and welding speed can effectively control the cooling rate of the weld seam. By optimizing the welding process, the cooling process of the weld seam can be made more stable, allowing sufficient time for hydrogen to escape, thereby reducing the possibility of crack formation from the process perspective.