Hardfacing Welding

What is Hardfacing?

Hardfacing is a welding-based process used to deposit a harder, more wear-resistant alloy onto the surface of a base metal. This significantly improves resistance to abrasion, impact, and mechanical wear, thereby extending the service life of the component.

The process utilizes specialized electrodes or filler wires and is typically performed using conventional arc welding methods. During hardfacing, the filler material is melted and metallurgically bonded to the substrate, forming a durable protective layer.

How Does Hardfacing Work?

Material Deposition: A hard alloy is deposited onto the surface of the base metal using welding electrodes or filler wires under controlled heat input.
Metallurgical Bonding: The surface of the base material partially melts and fuses with the filler metal, creating a strong metallurgical bond rather than a simple surface attachment.

The result is a dense, wear-resistant layer typically ranging from 1 to 10 mm in thickness. This hardfaced layer combines the properties of both the base metal and the deposited alloy, offering superior durability without replacing the entire component.

Are There Different Techniques for Hardfacing?

Yes. Hardfacing is commonly performed using two primary techniques: Build-Up and Overlay. These methods are used either to restore worn components or to reinforce new or lightly used parts to extend their service life.

Build-Up Hardfacing

Used to repair heavily worn components with gouges, scratches, and surface loss by rebuilding the original working profile.

Surface Restoration

Additional weld material is carefully deposited in damaged areas, followed by leveling and finishing to restore functionality.

Overlay Hardfacing

Applied to new or lightly worn parts using uniform weld passes to add a protective, wear-resistant layer.

Life Extension

Enhances durability and abrasion resistance without repair work, making it ideal for preventive reinforcement.

How Hardfacing is Performed?

Hardfacing is a specialized welding process designed to extend the working life of metal parts by building a hard, wear-resistant surface over the base material. Unlike typical welds, hardfacing covers the entire working surface rather than just seams or cracks.

Step 1: Clean the Part

All dirt, grime, oils, rust, and chemicals must be removed before hardfacing. Proper cleaning ensures strong adhesion and prevents weld defects such as inclusions, cracking, or warping. This applies even to new parts with coatings or paint.

Step 2: Build-Up Hardfacing

Repair any deep gouges, abrasions, cracks, or other surface damage. The surface should approximate the final desired shape. For new parts without damage, this step can be skipped.

Step 3: Buttering

Apply a thin buffer layer between the base material and hardfacing alloy, especially when using dissimilar metals. Buttering improves bonding and reduces the risk of cracking or shrinkage in the final layer.

Step 4: Apply Hardfacing

Deposit one or more coats of hardfacing material across the surface. The process can be spotty or complete depending on the workpiece’s purpose, typically requiring 1–3 layers.

HARD FACING

Where Is Hardfacing Often Used?

Hardfacing is widely used in applications where components are exposed to continuous impact, abrasion, or erosion. By reinforcing the working surface, it helps equipment maintain strength, dimensions, and performance over extended service periods.

Construction Equipment: Components such as excavator buckets, plow blades, and cutting edges endure severe impact and abrasive wear. Hardfacing strengthens these parts, reducing material loss and preserving operating dimensions.
Agricultural Machinery: In sugar processing, rollers used to crush sugarcane are subjected to constant mechanical stress. Hardfacing improves resistance to abrasion and impact, significantly extending roller service life.
Mining & Crushing Systems: Crusher jaws, wear plates, and liners are exposed to highly abrasive ore and rock. Hardfacing protects these critical components and can restore worn surfaces before full replacement is required.

Hardfacing often appears uneven and rough because it builds up material across the surface. Unlike conventional welds, the goal is durability and wear resistance rather than smooth seams.

Hardfacing is suitable for steels (carbon, alloy, stainless, manganese), cast iron, nickel-based alloys, and copper-based alloys. Materials that are too soft or used in non-wear-critical applications are generally not suitable.

Hardfacing is primarily used on high-wear components exposed to abrasion or impact. It is not effective for parts damaged by flexing or sheer stress alone.

Common processes include submerged arc welding and flux-cored arc welding. Other methods like plasma arc, laser welding, or brazing can also be used. The key factors are heat control and deposition rate to ensure strong, durable wear layers.

Common welding techniques used in hardfacing applications:

Plasma Transferred Arc (PTA) Welding

Laser Welding, Spray Fuse Welding, and Thermal Spraying

Oxy-Fuel Welding (OFW) or Oxyacetylene Welding

Gas Tungsten Arc Welding (GTAW or TIG Welding)

Submerged Arc Welding (SAW)

Shielded Metal Arc Welding (SMAW)

Gas Metal Arc Welding (GMAW or MIG) with Shielded Wire

Flux Cored Arc Welding (FCAW) with an Open-Arc or Gas-Shielded Hardfacing Wire

All metal parts even with normal use will wear as time goes by. This may cause them to lose their functionality and as a result, the need for a new part.

In certain industrial applications, like in mining or agriculture, this may happen more frequently. Hardfacing can be an ideal option for any metal part that may wear for being used. In short, hardfacing can help to:

Spend less downtime for replacing worn or broken components
Store fewer spare parts to inventory, because they are not needed
Longer equipment lifespan

Hardfacing is used for a wide range of applications, but we can highlight some examples.

Excavator plowshare
These parts suffer abrasion daily like any other construction equipment. The constant abrasion and erosion due to its daily outdoor heavy duty may significantly reduce the dimension and strength of the piece.
By hardfacing these parts, the total machinery lifespan can be extended many times, with a very reduced investment.

Sugar cane crusher roll
This part is constantly exerting pressure to mill the cane to extract the sugar to process. The sugar cane is a strong plant that can put these metal-made parts to the test.
Hardfacing is the usual procedure to extend the life of these parts, lowering production costs and downtime.

Mining crushing rolls
Mining is an industry quite related to hardfacing. The material obtained from the mine should be crushed to be processed.
Even with being made of hard material, in a short time these rolls are worn down because they deal with strong minerals all day long. So, more than a possibility, hardfacing is a must for mining crushing rolls.

There are several techniques and methods for applying hardfacing. The one you should choose will depend on your equipment and needs. Let’s talk about the techniques first.

Wear is typically caused by abrasion, impact, or metal-to-metal contact. Heat and corrosion can also contribute but are less common in hardfacing applications. Multiple wear types can occur simultaneously, such as abrasion and impact on excavator blades.

The ideal hardfacing machine handles long duty cycles, delivers consistent deposition, and minimizes the heat-affected zone. High-power welders (e.g., 220V) are generally more efficient, but most industrial-grade welders can perform hardfacing effectively. Equipment rentals can help test different machines before purchase.