Overlay Welding – Techniques, Applications, & Best Practices

Didn’t know anything about overlay welding? Well, it’s not something complex. It’s a very straightforward welding technique where a metallic layer is welded to enhance or protect the surface of another metal. This type of welding is quite useful for industries where there is a lot of risk of wear and tear of machinery, including aerospace, oil and gas, and mining.

So, what overlay welding does is, it increase the service life of machinery and parts cutting the requirement of replacing them with new ones. Hence, it saves a lot of money. Here, we will explain what exactly it is, how to do it, techniques you can do, safe practices, applications, benefits and limitations, and so much more.

So, if you’re a beginner welder or anyone related to this field, this knowledge is quite useful for you to understand this important welding technique.

What is Overlay Welding?

Overlay Welding

Overlay welding or weld cladding is a special technique where a metal is welded to protect the surface of another metal. The primary goal of this process is not only to provide protection but also to improve the properties of the metal without compromising or breaking the metal surface.

For instance, you can coat a hard, corrosion-resistant metal on any less durable metal. This will improve the metal quality and it will perform its duty longer than before.

Now, let’s move to the different types of weld cladding!

Types of Weld Cladding

Just like welding, overlay welding also has different types. Each of these types and techniques has several benefits over others and has different applications. Below is a detailed elaboration of these types.

1.Submerged Arc Welding (SAW)

SAW

During this method, a granular flux covers the entire metal, hence called submerged arc welding. It is very useful in producing high-quality thick welding coats. This technique has important applications in large scale industrial projects.

2.Gas Metal Arc Welding (GMAW)

GMAW

You have also known this technique as MIG welding. It involves a wire feeding gun that emits a gas to protect the welded surface from contaminations. This process is relatively easy to learn and has wide number of applications. Since, it’s versatile, you can use it for large scale and smaller projects alike.

3.Plasma Transferred Arc Welding (PTAW)

PTAW

It uses a plasma torch to melt the metal and a powder delivery system for overlay metal. Theis technique is very very accurate and you can use it to overlay smaller and delicate surfaces that are not easy to with other two techniques.

So which technique to choose? Well, SAW is best for the penetration abilities and speed, GMAW is very versatile, and PTAW offers extreme precision.

What are the Materials Used Commonly

The material usage totally depends on how you want the finished product to be. It’s entirely your choice to select the materials based on your desired outcome. Most commonly used materials for clad welding are:

All these materials make sure that the metals tolerate harsh environmental conditions and enhance their service life for a longer time.

What are the Applications of Weld Overlay Cladding?

As mentioned above, weld overlays have various applications and can be used in different industries. This improves longevity and enhances the functionality of the materials. Some important applications of overlay welding are discussed below:

Industrial Applications

• Oil and Gas

The oil and gas field is very complicated. The equipment used in the industry is exposed to frequent wear and tear, corrosion, and other environmental factors like high pressures. Flanges, pipelines, and valves started leaking over time.

To cater to that issue, corrosion-resistant alloys are welded through welder cladding process. It helps prevent all leakages and failures to guarantee safe and efficient operation.

• Mining

Mining tools and equipment are very strong and sturdy as they have to tolerate abrasive environmental conditions and wear and tear.

Weld cladding plays an important role to repair and reinforce these equipment, including excavator teeth, crusher hammers, and drill bits.

The process not only decreases downtime and upkeep costs but also increases service life.

• Power Generation

Weld overlay is critical for power plants to manage some essential components tolerating high pressure, high temperature, and corrosive steam. These include turbine blades and boiler tubes.

An overlaid protective layer protects them from wear and tear and corrosion besides boosting their efficiency.

• Aerospace

As with other equipment and tools, weld overlay protects landing gear and jet engine components from corrosion and wear.

If the process is done efficiently, it helps restore the original dimensions of the faulty components.

Repair and Maintenance Applications

Overlay welding is not only used to improve efficiency, but it also has applications in repairing and maintenance of different machine components.

You can repair damaged parts of your device by welding overlays. This technique is also very economical instead of replacing the parts with entirely new ones.

This is particularly true in the case of larger complex parts that are very expensive to replace.

What are the Benefits of Cladding Welding

So, there are multiple advantages associated with cladding welding. Some of the benefits are mentioned down below:

Extend Equipment Life

Welder cladding considerably increase the service life of different tools anf equipment by protecting them from wear and tear and corrosion.

Highly Economical

It is wise to overlay faulty components, especially if they are expensive. It reduces the cost of buying a new one and then replacing it.

Customization

You can improve the strength and efficiency of any material by using a metal alloy of your choice based on the properties you want in the finished product.

Less Downtime

If you are regularly upkeeping your faulty components through overlay welding, it saves a lot of downtime and reduce cost.

What are the Equipment Used?

You cannot perform the welder cladding process without using appropriate tools. There are several tools that are used for this purpose. We will discuss some of these equipment and tools in this section.

Welding Machines

• Automated Welding System

These are one of the most commonly used machines to in weld overlay applications to achieve consistent quality and even thickness of the overlay surface.

If you are working on a large-scale industrial project, the automated welding system is quite ideal for it as they provide precision and accuracy, such as aerospace and nuclear sectors.

You can use an automated welding system to perform a variety of welding techniques, including TIG, MIG, and SAW.

• Manual Welding Machines

These machines are very good for smaller intricate tasks where the automated welding machines don’t provide control. You can typically perform GMAW and PTAW with such machines. Make sure the welder is experienced and skilled enough to handle the intricacies of the welding.

Supporting Equipment

Besides welding machines, there are some supporting equipment that help perform the process of overlay welding. These supporting equipment are as follows:

• Wire Feeders

These are important for SAW and MIG and provide reliability and precision. So, make sure the weird feeders are capable enough to support. They basically control the consistency and speed of the wire feed to the welding zone. The wire feeder impacts the weld overlay cladding quality.

• Power Sources

Welding cannot be performed without a power source. So, you need a stable and right power source is important to maintain the needed energy output during the process of welding. The power sources manufactured for overlay welding must handle high currents and longer duty cycles without arc fluctuations and overheating.

• Oscillation Equipment

These equipment are very useful for welding techniques that need bead weaving. It helps spread weld deposits very evenly across the entire surface. This even distribution is primarily important when the area is large or when you need precision in overlay’s thickness and composition.

Safety and Control Equipment

Among supporting equipment, there are safety and control equipment that not only make the whole process safe and smooth but also keep the welder safe. The following are some of the most important safety and control equipment used in weld overlay services:

• Fume Extraction System

Weld overlay cladding produces a considerable amount of fumes and particulate matter. These extraction systems must be efficient for safe welding operation. It keeps the welder safe from inhaling fumes and reduces the risk of breathing issues and other related problems. You must ensure there are proper fume extraction systems, especially if you’re working in confined spaces.

• Cooling Systems

Just like simple welding, overlay welding also involves a lot of heat generation due to high-temperature flames. These high temperature not only affect the machinery but also the overlaying metal. Cooling systems manage welding equipment temperature to make sure they are not overheated and don’t produce uneven welds.

• Control Systems

Nowadays, the new welding machines have built-in advanced control systems that enable operators to fine-tune the parameters of the welding. With these control systems, you can operate can adjust voltage, current, wire feed speed, and other parameters to manage the welding quality and consistency.

• Personal Protective Equipment (PPE)

Personal safety is quite important for the welding process. So, it’s important to use personal protective equipment (PPE) during and after and overlay welding.

Welding helmets – The auto-darkening helmets keep the eyes and face of the welder from UV radiations, intense light, flames, and fumes.

Gloves and protective clothing – The gloves protect the hands and arms from skin burns and the protective clothing keeps the body safe from sparkling flames.

Respirators – Respirators protect the nose from toxic gases, fumes and poor ventilation.

What is the Difference Between Cladding vs Weld Overlay?

Cladding and weld overlay might seem the same, but they are actually different. Both of these enhance the properties of the surfaces, but the common difference between them is:

Weld Overlay Services

Weld overlay services provide a vast range of solutions to meet the specific needs of different industries and applications. These services are as follows:

Customized Weld Overlay Solution

Since they are customized, they are primarily tailored according to the specific needs of the projects and industries. It involves material selection and the methods of applications.

On-Site Welding

These services are useful for immovable components or large industrial projects where there is a use of heavy duty machinery or pipelines. So, there are different service providers that offer on-site welding functionality.

Inspection and Testing

Inspection is a must after overlay welding. Several providers offer careful inspections and testing to make sure that the integrity and performance of the weld cladding is preserved.

How to Perform Overlay Welding Process?

Overlay welding is a thorough process that needs to be precise and done after careful planning.

We will tell you all the main steps involved in overlay welding, starting from preparation to final touches.

Each step ensures the chemical and mechanical properties of the finished product.Here’s a step-by-step guide to the overlay welding process:

Step #1 Base Material Preparation

1. Cleaning

First things first, you need to clean the base material surface and get it rid from contaminants, such as oil, rust, and grease. Cleaning is mainly done with the help of chemical solvents, abrasive blasting, and mechanical brushing. If the surface is clean and smooth, it helps improve the quality of the welding.

2. Machining and Grinding

Based on the base material condition, it may have the need of grinding or machining to accomplish the desired surface profile. It helps achieve uniform surface which leads to a smoother and even overlay weld. Each step ensures the chemical and mechanical properties of the finished product.

3. Preheating

There are some materials that need preheating to prevent cracking and absorbing thermal shock before the actual welding. There is no specific value for the preheating temperature. It all depends on the material composition and thickness.

Step #2 Selection of Filler Material

1. Compatibility of Material

The material choice for the filler is entirely dependent on the properties you want in the final products. You can select the material based on corrosion resistance, thermal conductivity, hardness or wear resistance. However, you need to use only compatible metal with the base material to prevent delamination.

2. Material Form

There are various forms of filler materials. These are available in the form of wire, powder, and rod. The form of material you choose depends on what welding technique and weld overlay you choose.

3. Testing

In certain circumstances, different tests are conducted on samples to confirm whether the chosen material will perform well or not under expected functional conditions.

Step #3 Setup of Welding Equipment

1. Configuration

Configure and assemble necessary welding equipment according to the instructions of the manufacturer. During this, it’s important to set up power sources, wire feeders, and auxiliary equipment such as cooling systems and oscillators.

2. Calibration

Equipment calibration is very important to check welding parameters like current, speed, and voltage are according to the specific requirements of welding. This step ensures consistent and good quality welding.

3. Safety Checks

It’s important to perform safety checks to confirm that the equipment are operating in top condition. Check that all the safety measures are met before starting the welding process.

Step #4 Welding Process

1. Arc Initiation

Start the welding process by initiating the arc. You need to select the welding technique on your own choice, be it automated welding system or manual welding system.

2. Layering

Apply filler material in the form of layers and monitor the deposition very carefully to keep a check on the coverage and right penetration. Clad welding sometimes needs multiple passes to achieve adequate thickness of the material.

3. Monitoring

Monitor the process very constantly and check for any signs of welding defects. Look for posterity, cracks, uneven filling and other defects. Make adjustments based on the type of defect you recognize.

Step #5 Finishing and After Weld Treatment

1. Cooling

The welded material is allowed to cool down before putting it aside for finishing. Cooling should be done under a precise environment to prevent warping and stress.

2. Inspection & Testing

Now comes the inspection step. After cooling the welded material, do a visual inspection again and look for defects. Make changes according to the defect. If you don’t find any defect visually, its better to perform other non-destructive welding inspection methods.

3. Post-Weld Heat Treatment

Based on the overlay type, perform heat treatment to reduce stress and enhance the metallurgical properties of the whole welded area.

4. Polishing and Machining

In the final step, machining and polishing of the welded surface is done to get the desired dimension and finishing of the material.

It’s important to follow each and every step mentioned to accomplish a smoother and even welding finish. It helps achieve defect-less welding and saves a lot of money on repeated replacements.

Weld Overlay Cladding Challenges and Solutions

Though overlay welding has dozens of benefits, yet it pose challenges that directly impact the welding quality, it’s efficiency, and welding process outcome. So, it’s important to fully understand the challenges of overlay welding to make the welding process effective.

Some of the common issues that welders face during overlay welding with their solutions are mentioned down below. Have a look:

1. Material Compatibility

It’s very important that the overlay metal and the base material are compatible with each other In case of incompatibility, the weld will not be as strong as it should be. Also, it will not do much in increasing the chemical and mechanical properties of base materials. Ultimately, the metal will corrode and have poor bonding.

For this, do your research and invest time in finding the best compatible combinations of filler and ase material. Consult compatibility charts and carry out metallurgical analysis to check the compatibility of the materials under specific conditions.

It’s suggested to conduct preliminary tests like small scale welding trials to see base and filler material interaction. Make material choice adjustments based on the results of the tests.

2. Stress and Distortion

As you know heat is involved in the welding process, this heat sometimes cause the expansion and contraction of the material. This thing lead to distortion and residual stress. It will not only have a negative effect on the appearance of the material but also cause damage to the structural integrity and performance of the material.

To solve this issue, use controlled heat input techniques to reduce metallic thermal impact. Also, it’s advised to preheat the base material before welding to reduce distortion.

3. Getting Desired Properties

As mentioned earlier, overlay welding is performed to enhance the chemical and mechanical properties of the base material like wear and tear, corrosion, and hardness. Achieving this is a huge challenge because of the varying welding parameters and the behavior of the materials.

So, it’s important to carefully monitor the parameters and make quick changes based on welding requirements

Conclusion

Overlay welding is an important technique to improve the properties of the material like corrosion, hardness, and wear and tear. You can use different techniques for overlay welding, such as submerged arc welding (SAW), gas metal arc welding (GMAW), and plasma transferred arc welding (PTAW).

If you talk about the applications of the welder cladding, there are many. It is used in oil and gas, mining, aerospace, power generation sectors, and so many others.

You have to follow all the steps of the overlay welding mentioned in the article. It will make sure the welding outcome is consistent and without any defect.

However, you need to use personal protective equipment before starting to perform these welding tasks.