How to weld a titanium forged disc?

Titanium forged discs are highly sought - after components in various industries due to their excellent properties such as high strength - to - weight ratio, corrosion resistance, and good biocompatibility. As a reliable titanium forged disc supplier, I am often asked about the welding process of these discs. In this blog, I will share in detail how to weld a titanium forged disc.

Understanding Titanium Grades for Forged Discs

Before diving into the welding process, it's crucial to understand the different grades of titanium forged discs. We offer Gr1 Titanium Forging Disc, Gr2 Titanium Forging Disc, and Gr5 Titanium Forging Disc.

Grade 1 titanium is the most ductile and softest of the commercially pure titanium grades. It is highly formable and has excellent corrosion resistance, making it suitable for applications where formability is a key requirement. Grade 2 titanium has slightly higher strength than Grade 1 while still maintaining good formability and corrosion resistance. Grade 5, also known as Ti - 6Al - 4V, is an alloy that combines aluminum and vanadium. It offers high strength, good weldability, and is widely used in aerospace, medical, and other high - performance applications.

Pre - welding Preparations

Material Inspection

Before welding, carefully inspect the titanium forged discs. Check for any surface defects such as cracks, scratches, or inclusions. These defects can lead to welding problems and affect the quality of the final weld. Use non - destructive testing methods like ultrasonic testing or penetrant testing to detect internal and surface defects respectively.

Cleaning

Titanium is very sensitive to contaminants such as oil, grease, dirt, and oxides. Any contaminants on the surface of the discs can cause porosity, cracking, or reduced corrosion resistance in the weld. Clean the surfaces to be welded thoroughly using a suitable solvent such as acetone or isopropyl alcohol. After cleaning, use a stainless - steel wire brush to remove any remaining oxides. It's important to use a dedicated brush for titanium to avoid cross - contamination.

Joint Design

The joint design plays a significant role in the welding process. Common joint designs for titanium forged discs include butt joints, lap joints, and T - joints. The choice of joint design depends on the application requirements, the thickness of the discs, and the welding method. For butt joints, ensure proper fit - up with a small root opening and minimal gap. A misaligned joint can lead to uneven heat distribution and poor weld quality.

Welding Methods

Gas Tungsten Arc Welding (GTAW)

GTAW, also known as TIG (Tungsten Inert Gas) welding, is one of the most commonly used methods for welding titanium forged discs. This method uses a non - consumable tungsten electrode to create an arc between the electrode and the workpiece. An inert gas, usually argon, is used to shield the weld area from atmospheric contamination.

• Equipment Setup: Select a suitable GTAW welding machine with a high - frequency start to ensure a stable arc. Use a pure tungsten or thoriated tungsten electrode depending on the welding current. Set the appropriate welding current, voltage, and travel speed according to the thickness of the discs and the joint design.
• Shielding Gas: Argon is the most commonly used shielding gas for GTAW of titanium. It provides excellent protection against oxidation and nitrogen absorption. Ensure a sufficient flow rate of the shielding gas to cover the weld area completely. In some cases, a trailing shield may be used to protect the hot weld metal as it cools.

Plasma Arc Welding (PAW)

PAW is another option for welding titanium forged discs. It is similar to GTAW but uses a constricted arc, which results in a more concentrated heat source and higher welding speeds.

• Advantages: PAW offers better control over the weld pool, higher penetration, and less distortion compared to GTAW. It is suitable for welding thicker titanium discs.
• Process Parameters: Adjust the plasma gas flow rate, welding current, and travel speed carefully. The plasma gas is usually argon, and a secondary shielding gas is also used to protect the weld area.

Welding Process

Welding Environment

Titanium welding should be carried out in a clean and controlled environment. Avoid welding in areas with high humidity, dust, or strong air drafts. A welding booth can be used to isolate the welding area and maintain a stable environment.

Arc Initiation

When starting the arc, use a high - frequency start to prevent contamination of the tungsten electrode. Once the arc is established, maintain a stable arc length. A long arc can cause oxidation and porosity in the weld, while a short arc can lead to electrode contamination and poor weld appearance.

Welding Technique

Move the welding torch at a consistent speed along the joint. Avoid stopping the arc suddenly as this can cause crater cracks. Use a weaving technique if necessary to ensure proper fusion and distribution of the filler metal (if used). When using filler metal, feed it into the leading edge of the weld pool at a uniform rate.

Post - weld Cooling

After welding, allow the weld to cool slowly. Rapid cooling can cause residual stresses and cracking in the weld. Cover the weld area with an insulating blanket or use a post - weld heat treatment to control the cooling rate.

Post - welding Treatment

Inspection

After welding, inspect the weld using non - destructive testing methods such as radiography, ultrasonic testing, or visual inspection. Check for any weld defects such as porosity, cracks, lack of fusion, or incomplete penetration. If any defects are found, they should be repaired immediately.

Heat Treatment

Depending on the application requirements, post - weld heat treatment may be necessary. Heat treatment can relieve residual stresses, improve the mechanical properties of the weld, and enhance the corrosion resistance. The heat treatment process should be carried out according to the specific titanium grade and the welding procedure.

Surface Finishing

The welded area may require surface finishing to improve its appearance and corrosion resistance. This can be done by grinding, polishing, or pickling. Grinding can remove any excess weld metal and smooth the surface, while pickling can remove any oxide layers and improve the surface finish.

Quality Assurance

Welding Procedure Qualification

Develop and qualify a welding procedure specification (WPS) for each type of titanium forged disc and joint design. The WPS should include details such as the welding method, process parameters, pre - and post - welding treatments, and quality control measures. Conduct welding procedure qualification tests according to relevant standards such as AWS D1.9 or ISO 15614.

Welder Qualification

Ensure that the welders are qualified and trained to weld titanium. Welders should have a good understanding of the properties of titanium, the welding process, and the quality requirements. They should be certified according to relevant welding codes and standards.

Conclusion

Welding titanium forged discs requires careful planning, proper preparation, and strict quality control. By following the steps outlined in this blog, you can achieve high - quality welds with excellent mechanical properties and corrosion resistance. As a titanium forged disc supplier, we are committed to providing high - quality products and technical support to our customers. If you have any questions about welding titanium forged discs or are interested in purchasing our products, please feel free to contact us for further discussions and procurement.

References

• AWS D1.9: Specification for Welding Aluminum
• ISO 15614: Specification and qualification of welding procedures for metallic materials
• Titanium: A Technical Guide, ASM International