Which Hardfacing Process is Right for Your Application?
November 28, 2017
Hardfacing is a welding process used to apply a material with increased hardness, ductility, erosion-resistance, and/or corrosion-resistance relative to the base (parent) material. It is also commonly referred to as cladding or hardsurfacing. Due to hardfacing materials improved properties, a part’s service life is prolonged. Hardfacing can be applied to new part to offer a value-added feature, or it may also be applied to repair previously deteriorated parts.
The most popular procedures used to apply hardfacing are:
- Flux cored arc welding (FCAW)
- Open arc welding / gasless welding (OAW)
- Gas metal arc welding (GMAW)
- Shielded metal arc welding (SMAW)
- Submerged arc welding (SAW)
- Gas tungsten arc welding (GTAW)
- Oxyfuel or oxyacetylene welding (OFW)
- Thermal spraying
Flux Cored Arc Welding
FCAW is a semi-automatic or automatic arc welding process. This process typically requires a continuously-fed tubular electrode containing a flux (a chemical substance added to the welding environment as a cleaning agent, flowing agent, purifying agent or combination thereof) and a constant voltage. This welding process is often chosen in construction applications because it is quick and easily transportable.
Open Arc / Gasless Welding
OAW is a semi-automatic or automatic arc welding process. This process typically requires a continuously-fed tubular electrode that may or may not contain flux, and a constant voltage. This welding process is often chosen in field applications because it is quick, easily transportable, and requires no gas connection.
Gas Metal Arc Welding
GMAW (sometimes called MIG -metal inert gas welding) is a semi-automatic or automatic welding process in which a consumable wire electrode and shielding gas are fed through a welding gun. A constant voltage is most commonly used with this process.
This process is chosen because it provides high quality welds that can be deposited much faster than with SMAW or TIG welding processes. It is also versatile in that it can be used with a wide range of alloys and operated in multiple ways.
It is passed over when the application requires mobile flexibility as it cannot be used in the vertical or overhead welding position.
Shielded Metal Arc Welding
SMAW is a manual arc welding process that uses a consumable electrode coated in flux.
An electric current forms an electric arc between the electrode and the base metal. As the weld is laid, the flux coating disintegrates and forms a shielding gas and a layer of slag which protect the weld until it cools. This is a common method of welding as the process and equipment are relatively simple.
Submerged Arc Welding
SAW involves the formation of an arc between a continuously-fed wire electrode and a workpiece – similar to GMAW. This process uses a flux to create protective gases and slag to the weld pool. Before welding, a thin layer of flux powder is placed on the workpiece surface itself. The arc then moves along the line and excess flux is recycled via the flux feed hopper.
SAW is often chosen because of its high quality welds (often with little operator skill required), minimal fumes, and relatively high metal deposition rates.
A major disadvantage is that it can only be welded in flat or horizontal position.
Gas Tungsten Arc Welding
GTAW (or TIG – tungsten inert gas welding) is a welding process that produces an arc between a non-consumable electrode and the workpiece. The weld is shielded by a shielding gas that forms around the weld area. GTAW can be performed manually or adapted to automatic equipment. This process is very versatile as it can be welded in all positions and with most metals. This process is commonly chosen for critical applications in the nuclear, chemical, and aerospace industries.
GTAW produces exceptionally high quality welds. The major drawback of this process is that deposition rates with manual welding are low.
Oxyfuel or Oxyacetylene Welding
OFW is a group of welding processes that use heat with a fuel gas flame with or without the application of pressure and with or without the use of filler metal. OFW includes any welding operation that uses a fuel gas combined with oxygen as a heating medium.
Because of the control the welder has over the rate of heat input, and the temperature of the weld zone, it is well suited for the welding of thin sheet, tubes, and small diameter pipe.
Thermal spraying is a coating process that consists of a heat source and a coating material in either powder or wire form that is melted and sprayed onto surfaces at high velocity. There are three major categories in the thermal spray processes family: Flame spray, electric arc spray, and plasma arc spray. There are several of sub-categories under each.
Thermal spray advantages include:
- High throughput rates
- Low heat input rates
- Wide variety of materials can be used
- Favorable economics
- Easily repeatable process
If you have any questions regarding processes or applications, contact us and we will get you in touch with one of our technical experts.