While welding is often used to join metals together, it can also be used as a protective technique. Weld overlay, also known as weld cladding, is the process of melting a protective layer of metal atop another metal surface. The application of laser light heats and melts the cladding metal onto the parent metal, creating a welded surface with greater corrosion or wear resistance. In some cases, multiple metals will be alloyed or layered over one another to enhance the surface’s properties even further.
Weld overlay can be further classified based on its function. Corrosion-resistance overlay, as its name suggests, is used with chrome or nickel based metals to protect against oxidation. Hard-facing weld overlay is similar, but it is performed with the aim of increasing wear resistance. These processes offer a cost-effective and economical way to extend the equipment’s working life.
Titanova offers expert laser cladding and hard-facing services that ensure quality results at affordable prices.
Types of Weld Overlay Processes
To create an effective overlay, providers will match both the materials and the welding technique to the project. To do so, they must consider the goal of the overlay, the properties of the parent metal, and the characteristics of the work environment.
Some of the application options include:
- Laser Welding. Typically an automated process, laser welding uses a focused beam of light to quickly melt the cladding into the parent metal. Laser offers high efficiency and excellent results with a smaller heat-affected zone than is possible with conventional arc welding.
- Shielded Metal Arc Welding (SMAW). Among the most common welding techniques is shielded metal arc welding, which is more affordable than some other options. It is a manual process that requires the use of a flux-coated consumable electrode. An electrical current creates an arc between the electrode and the metal surface, melting it to join the cladding to the parent metal. The flux melts to create its own shielding gas and produce slag, which adds additional protection to the overlay.
- Metal Inert Gas (MIG) Welding. MIG welding is like SMAW welding in that it uses a consumable electrode that melts to form an overlay. However, the electrode does not contain flux, so the shielding gas must be added separately.
- Tungsten Inert Gas (TIG) Welding. TIG welding is another shielded arc welding technique, like MIG, but it uses a non-consumable electrode. A separate wire is used to add filler material.
- Plasma Transferred Arc (PTA) Welding. PTA welding is an inert-gas process that uses a non-consumable electrode like TIG welding. The major difference is that the cladding material is added directly to the arc as a powder.
- Submerged Arc Welding. As its name suggests, submerged arc welding is distinct from other processes because the arc stays hidden—or submerged—beneath the flux blanket. In other respects, submerged arc welding closely resembles SMAW.
Laser Weld Overlay Process Benefits
Laser weld overlays offer significant advantages compared to other surface treatments, including other weld overlays. Because it produces the lowest dilution of any overlay technique, laser cladding is highly economical. The lower heat input also decreases the risk of overheating, meaning that it can be used with parts of all sizes, and the resulting heat-affected zone will be very small. Laser cladding also produces smooth, flat cladding free from surface imperfections. Items Laser clad require little to no finishing, further improving the efficiency of the process.
Industries and Applications
Laser cladding is used in any industry where iron-based metals are exposed to environmental conditions like abrasive materials, precipitation, moisture, or corrosive chemicals. For instance, construction, mining, and excavation equipment can often benefit from hard-facing, as can plumbing components.
Industries whose operating conditions make laser cladding a good option include:
- Power generation
- Petrochemicals
- Biopharmaceuticals
- Equipment manufacturing
- Wastewater and water treatment
- Construction
- Mining
Materials Often Used for Weld Overlay
Just as important as the choice of welding overlay technique is the choice of material. Not all metals can be welded together—titanium, copper, and aluminum, for instance, are poor candidates for overlays.
Some materials that tolerate cladding well include:
- Stainless steel
- Chromium-based alloys
- Nickel-based alloys, including Inconel and Hastelloy
Your provider will help you evaluate surface treatment options and determine whether a weld overlay is right for your situation.
Weld Overlay Services by Titanova
Titanova is a full-service, ISO 9001:2015-certified laser shop offering expert welding, hard-facing, and weld overlay cladding. To learn how a weld overlay could improve your equipment’s performance, contact our team today.