Hardfacing: What Is It and How to Do It Right

09. 21, 2022

Some people have the idea that hardfacing is a complicated business, intended only for a small elite of welding pros.

Other ones see hardfacing as a troublesome process that should be avoided.

In reality, hardfacing is a special process that can be done with the only purpose of extending the service's life of any equipment or surface.

Now, if a metal part reaches a longer lifespan through hardfacing, more time can be used and fewer times will need to be replaced.

So, hardfacing is a good idea when there is a need for saving money.

Even when hardfacing has several techniques to be done, it is not something too hard to understand.

So, let's get started by defining what hardfacing is.

What is hardfacing?

Hardfacing is the process to apply a tougher material to a base metal, to make it more durable or extend its lifespan.

This harder material is welded to the base metal by using specialized electrodes or filler rods.

They are meant to form very dense and thick layers (between 1 to 10 mm) above the base metal of wear-resistant material with high bond strength.

The coating material can add ductility, hardness, corrosion resistance, and erosion resistance to the original part.

Other names given to hardfacing are hard surfacing, surface welding, and cladding.

Among the base metals that can be hardfaced are the following ones:

ㆍCast Iron

ㆍCopper-base Alloy

ㆍNickel-base Alloy

ㆍStainless Steel

ㆍManganese Steel

ㆍCarbon and Alloy Steel

Many manufacturing equipment is made from low-alloy and higher carbon steel. Hobart's filler metals are a complete solution whatever the base material.

Before starting any hardfacing process is needed to identify exactly what material is made the part of because this defines the pre-heat and post-heat temperature that should be applied.

These pre-heats and post-heat settings are even more important as the alloy percentage of the part content are higher.

Why hardfacing may be needed?

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:

ㆍSpend less downtime for replacing worn or broken components

ㆍStore fewer spare parts to inventory, because they are not needed

ㆍLonger equipment lifespan

The savings from hardfacing

Industrial equipment is intended to last for many years. So, many companies take some years to replace theirs.

Most of the time, hardfacing is applied to used rebuild machinery, but even new equipment can be hardfaced to make it more wear-resistant.

Hardfacing parts from equipment for many years can mean saving between 25-75% of the cost of replacement parts.

On recent equipment, hardfacing can help to extend up to 300% of the lifespan of the parts.

What techniques and methods for hardfacing are there?

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.

Techniques for applying hardfacing

Hardfacing can be used to overlay, build-up, or both techniques at the same time. Each technique (or the combination of both) has a purpose.

The overlay is a technique used to avoid metal loss by adding a welded layer to the base.

The build-up technique restores older equipment worn by abrasion or impact to its original dimensions by placing several weld layers (each one on top of the other).

While the part is sound a combination of these hardfacing techniques can be used once and again.

Some of the most common coating materials used for hardfacing are:

ㆍCobalt-based alloys (like stellite) for wear and corrosion resistance

ㆍCopper-base alloys for rebuilding worn machinery parts

ㆍIron chromium alloys for high-stress abrasion

ㆍChromium carbide alloys

ㆍNickel-based alloys for metal-to-metal wear resistance

ㆍManganese steel for wear application

ㆍTungsten carbide for high-stress abrasion

ㆍNOREM

The one you should use for your equipment can be defined by the base metal and the method of choice.

There are many methods to apply hardfacing, like the following ones: