Hardfacing Makes Tough Tougher
Have you ever needed to increase the strength of a metal part to help prevent wear?
Hardfacing is a fairly simple and effective way to decrease wear on your metal parts, helping them to succeed in their intended use. Keep reading to learn what hardfacing is & how to use it to your advantage in welding.
What is Hardfacing?
In simple terms, hardfacing (also known as hard surfacing) is a layer of impact-resistant and wear-resistant coating. This helpful coating can be applied to a part in order to increase its durability and service life.
The hard-facing process allows the equipment to be subjected to very harsh environments with fewer breakdowns and less downtime.
Hardfacing alloys come in a wide variety of specifications which are carefully selected to maximize the performance of the component to which they are to be applied. The hardfacing process can be used to build up surfaces that have already become worn down due to use, or to proactively armor surfaces on new parts before they are put into service. Hardfacing can be accomplished using a variety of processes, both in a shop and in the field, making it very versatile and cost-effective.
Additionally, using this process on new parts can extend service life by up to 300%. Still, if you hardface worn parts, you can save up to 75% versus replacement cost. Hardfacing does not require any specialized equipment and can be accomplished using equipment commonly found in many fabrication shops, repair departments, and garages.
What Parts Are Hardfaced?
Carbon steel, stainless steel, manganese steel, cast steel, cast iron, and a variety of alloys can all be hardfaced. The most commonly hardfaced items include those in various industries including:
- Mining industry: (crusher rolls, buckets, bucket teeth, screw conveyors, pan conveyors, blades, sprockets, rollers, hammers, and trackpads)
- Agricultural industry: (sweeps, teeth, shares, shoes, shovels, furrowers, plows, knives, cutters, rippers, hoes, chisels, spikes, blades)
- Construction industry: (augers, buckets, bucket teeth, moldboards, dozer blades, shears, grousers)
These tools often see extensive use in some of the most demanding environments on earth and may only last hours or days without being hardfaced. Spending a few hours of time hardfacing these items can yield weeks or months of service life gain, eliciting the famous Benjamin Franklin proverb “an ounce of prevention is worth a pound of cure.”
How Is Hardfacing Applied?
Hardfacing can be accomplished using a wide variety of processes including:
- flux-cored arc welding (FCAW),
- gas metal arc welding (GMAW)
- submerged arc welding (SAW)
- shielded metal arc welding (SMAW)
- oxy-fuel welding (OFW)
- plasma transfer arc (PTA)
- welding, resistance (stud) welding, and thermal spraying
The process selected is typically a result of what is available, what type of coating is to be applied, and where the application will take place.
Shielded Metal Arc Welding
If a piece of equipment in a remote area breaks down, it would be impractical to choose a submerged arc process to repair it, as the equipment is large, heavy, and stationary. In this instance, shielded metal arc welding (SMAW) would be a better choice, as this process can be performed quickly and inexpensively in the field.
Alternatively, if new equipment is being fielded for the first time, automated processes with a higher deposition rate are preferred due to speed and repeatability.
Flux-cored Arc Welding
Similarly, flux-cored arc welding (FCAW) is performed using inexpensive, readily available equipment in either a shop or field environment. Consequently, it’s one of the most popular processes for hardfacing applications. There are 3 patterns commonly used for FCAW and similar processes.
- Waffle Pattern: In the waffle or herringbone pattern, you can crisscross welds to form squares. Next, smaller aggregates such as sand, dirt, and gravel can form a “dead bed” which acts as a secondary protective layer.
- Dot Pattern: For equipment that will often encounter larger aggregates, a dot pattern may be chosen. This method consists of a series of dot-shaped welds which can vary in size and distance to both minimize warping of the base material and to allow a “dead bed” to form with the size of the aggregate that the equipment is expected to encounter most often.
- Stringer: The third common pattern is a stringer. Stringer beads are run in parallel and spaced at various distances from .25” to 1.5”. For larger aggregates, the beads should run parallel to the material flow. If you are considering hardfacing a piece of equipment, there are many options for achieving the desired result. If you are unsure of what process, filler, or shielding gas is appropriate, please contact your local welding supplier.
Hardfacing is Not as Hard as it Seems
In summary, hard facing is an effective and not-so-difficult way to reduce wear on your metal parts. Hopefully, you now know more about what hard facing is, its uses, and the standard application processes.
To read about other welding tools and processes, you can view our resources to learn more!