Flux Cored Welding Wire

AES stock a vast range of fluxed cored and metal cored welding wires, available in gas shielded and gasless varieties. We are working hard at putting these on our website, so if you cannot see the product here yet, or just need technical support, call us free on 0800 975 94710.

Why use flux cored welding wire?

If welding with a solid wire is satisfactory, why use a higher priced flux cored wire? A flux cored wire is optimised to obtain performance not possible with a solid wire. For many welding applications like vertical-up welding, flat welding, welding over galvanized, or welding hard-to-weld steels, a flux-cored wire can do it better and faster.

Although gas metal arc welding (GMAW) with a solid mild steel wire is popular, easy-to-use, and effective for many applications, although it does have its limitations. For example, GMAW is slow for out of position welding. It’s either limited to short-circuit transfer and restricted by many welding codes due to the tendency for lack of fusion, or pulse transfer, requiring a special welding power source. It also requires very clean steel.

The ability to add a variety of materials to the core of the welding wire allows many performance enhancements to be made. Slag formers are added to shield the weld pool and shape and support the weld and iron powder increases deposition rates. Powdered alloys are added to produce low-alloy deposits or to improve the mechanical properties. Finally, scavengers and fluxing agents refine the weld metal.

Why be limited by a solid wire when a flux cored wire can do it better and faster? Select the flux cored wire optimised for your welding application, using it will increase your productivity and lower your costs. There’re two main types of flux cored wire available in today's market, gas shielded flux cored wires (FCAW-G), and self-shielded flux cored wires (FCAW-S).

Gas shielded flux cored welding wires

Gas shielded flux cored wires (FCAW-G) were introduced to the market around 1957. The core ingredients for this type of flux cored wire have been formulated to obtain performance impossible to achieve with a solid MIG welding wire. As all of shielding is provided by the shielding gas, the core materials may be carefully selected to maximize a certain area of welding performance. For example, obtaining smooth spray type transfer with 100% carbon dioxide shielding gas and welding speeds twice as fast in the vertical position.

Gasless (self-shielded) flux cored wires

Self-shielded Flux cored wires (FCAW-S) were introduced to the market later than Gas-shielded flux cored wires, around 1961. How are they different from gas shielded flux cored wires you might ask? Self-shielded Flux cored wires don’t require shielding gas because the core materials of the wire itself is designed in such a way, that when welding through the arc, it produces its own shielding gases as well as slag formers and compounds to refine the weld pool. The benefits of self-shielded flux cored wires lie in its simplicity. Ideally, they may be used outdoors in heavy winds without shelter and the additional equipment required for gas shielding.

MasterWeld Flux Cored Wires – Leading The Way In Maintenance Applications

The MasterWeld range of specialist flux cored wires are designed to save time and money combining all the benefits of flux cored wires for difficult maintenance applications in many different industries. After many years of expertise in this field and product development the MasterWeld range is probably the most diverse in the industry offering solutions to the most difficult maintenance welding applications. Our sales department has many years of metallurgical experience and after a careful analysis of the application, will recommend the right product for your application. Please see below many industries which these flux cored welding wires are of benefit.

Steel Production Industry

Processing of iron ore

Every day, tons of raw materials are processed in blast furnaces with many signs of wear. All manufacturing processes of steel production are subject to extreme conditions such as shock, temperature, corrosion, fumes etc. a durable wear.

The MasterWeld flux cored wires for these processes on are specifically designed to help reduce costs due to longer life.

Sinter plants

Throughout the process of sintering plant, different abrasion. Whether the mixture of coke, limestone and iron ore, the burning process or the subsequent crushing of the sinter cake, each phase is accompanied by severe wear.

Through extensive product development in the MasterWeld range, the life of the components in the manufacturing process are greatly increased.

Blast furnace

High temperatures, corrosive fumes and chemical processes accompanying the melting process results in all parts being subjected to severe abrasive and corrosive wear.

The MasterWeld products for this application offer excellent protection against this type of abrasive and corrosive wear.

Continuous casting and rolling

The transition stage in steel production from liquid to solid state results in considerable wear due to the combination of thermal fatigue and friction of metal on metal.

When rolling the rollers and machine parts are exposed to high temperature fluctuations.

The MasterWeld flux cored wires for this industry have been for many years currently developed specifically for these different requirements and are shown to be able to improve the lifetime and thus reduce maintenance costs.

Cement Industry


The best armour and lining of the mill guarantee optimum working conditions. Only by proper coordination of all components can the grinder for long periods of time. Our many years of international experience puts us in a position accurate make analysis of the Operating Conditions and recommend the right Masterweld products.

Rotary kiln

The main bottleneck in a cement factory, the rotary kiln. Every fault and the associated shutdown of the entire system is of course highly uneconomical. The more important is a quick and effective maintenance welding solution with the most effective MasterWeld products.

Concrete processing

The world's most widely used building material with its constituents of water, sand, bricks and cement in the production by the rotation of a permanent chassis and paddling abrasion. The failure or repair times of mixers and pumps can be very high.

MasterWeld flux cored wires drastically reduce the wear process that takes place in this industry.

Agricultural Industry


All machinery used in agriculture, especially for working the soil, subject to a continuous abrasive wear.

It is possible for the life of the agricultural machinery and components to increase enormously.

Oil presses

High pressure and temperature during the pressing process in the screw channels causes severe wear of the surfaces.

With the addition of MasterWeld flux cored wires we can permanently improve the surface quality thus providing greater productivity of the oil press.

Sugar Industry

With the accumulation of harvest debris resulting in severe wear to component parts. As an economical alternative to the regular replacement, or repair of the affected parts may be the use specialist flux cored wires suitable to the food industry thus effectively improving the life of these parts.

For rolling in the juice of the sugar mill, we have developed MasterWeld products that optimize the surface properties thus enabling higher productivity.

Recycling Industry

Recycling of metals

The shredding of cars is the most common form of steel recycling, during this process the hammers of the shredder are exposed to a variety of materials causing maximum wear resulting in frequent replacement of parts and considerable downtime. A protective layer with the correct MasterWeld flux-cored wire provides considerable improvement to the life of these parts.

Recycling of plastic, glass and building materials

Although requirements for this industry are considerably different, due to the abrasive substances that are used, parts wear out considerable quickly. The MasterWeld flux cored wires offer a considerably cost-effective alternative to the replacement of these parts.


The combustion process in a waste incineration plant causes corrosive and hazardous fumes. The MasterWeld stainless flux cored wires with the addition of special alloys offer a solution to these corrosion problems caused by these complex chemicals thus enabling a safe and efficient operation of the plant.


The interior of a combustion chamber is exposed to the chemical reactions to severe corrosive caused by fly ash. With this severe wear, this can cause damage to the boiler wall resulting in costly maintenance, with weld deposits of the correct MasterWeld flux cored wire the cost savings are considerable.

Electrical Industry


Fossil fuels (coal, oil, gas) power plants Hydropower plants Nuclear Power Plants Biomass power plants Wind energy


All parts of the plant for loading and unloading, conveying, grinding, mixing, etc. are exposed to severe abrasion. To ensure the smooth operation of major power plants protection of these parts is important to the operator.

With the use of the correct MasterWeld flux cored wires in these important parts of the plant wear is reduced and the profitability will increase.

In the pulverization of coal for power plants there are diverse applications of our products, to reduce the wear and reduce unnecessary downtime.

Water and wind

Wind and water turbines are exposed to various types of stress. These are a combination of erosion, cavitation, and mechanical fatigue.

With the use of the correct MasterWeld flux cored wires in these important parts of the plant wear is reduced and the profitability will increase.


When transporting or feeding biomass material in power plants, the contamination from sand, earth or stones causes heavy wear and possible failure of the augers.

The solution to this problem is a protective layer with the correct MasterWeld flux cored wire. MasterWeld flux cored wires for the mining industry.

Mining Industry

Extraction of raw materials

The extraction of raw materials such as ores, brown coal or potash needs a well-functioning Machine to ensure good return on investment. The correct MasterWeld flux cored wire can reduce the wear caused by these moving parts on teeth etc seriously reducing downtime and replacement of expensive parts. Different soil compositions require different impact/abrasive resistance, and it is vital that the correct flux cored wire is used for the job.


For processing of mined rock crushers are used different.

When shredding tremendous forces acting on the machine. Large print and related temperatures reduce the use of set time of the breakers.

The specially developed products from MasterWeld can reduce the wear of the machine.


Construction and earthmoving equipment must function properly in everyday use in the most demanding environments.

All surfaces that encounter hard rock mineral are subject to a high abrasion. To minimize downtime, we highly recommend the use of MasterWeld flux cored wires for hardfacing the surface thus considerably reducing downtime incurred.

Oil and gas industry


Oil and gas extraction Separation and transportation of crude oil Valve trim Petroleum Refinery Petrochemical Industry Raw chemicals


The oil and gas production are moving steadily in the border area of technology. Corrosion and mechanical conditions warrant maximum performance of the materials used. With the continuous development of material science, MasterWeld flux cored wires are now at the forefront of technology available due to constant research and development resulting in new and improved alloys to resolve new challenges that arise in this ever-changing environment. Valves must operate reliably in extremely corrosive environments. MasterWeld flux cored wires contain the best combination of alloys for these toughest areas.

Advantages and disadvantages of metal cored wires

In today’s world, fabricators have a wide range of choices in deciding the best welding process and consumable to use in a particular application. Many different considerations are necessary including welder skill, equipment, availability of the consumable, environmental issues, and the economics of the process. What is the best method to accomplish the task of joining two pieces of steel? One rapidly growing process is being seen in the use of metal cored wires. Higher duty cycles, faster travel speeds, low fumes and better cost effectiveness are some of the primary reasons. By exploring the advantages and disadvantages of the metal cored wires, you can best determine whether this is a process that you should employ to increase productivity and ultimately your profitability.

Since the day the carbon arc process to join two pieces of metal was discovered, we have been looking for ways to improve upon the process. At the turn of the century, Oscar Kjellberg developed the first coated electrode. In the 1930’s the first inert gas welding process (GTAW) was used as well as the first submerged arc welding (SAW). The main goal in every advancement was to improve first the integrity of the weld and second to improve upon the process itself, to make it faster, more efficient, and more cost effective through higher productivity. In 1948 the solid wire process was developed, and this expanded the usage of continuous solid wire applications that were not readily adaptable to the SAW process such as vertical and overhead welding.

Manufacturers and fabricators who depended a great deal on the welding process for their finished products were not totally satisfied with these improvements, they wanted more. In the 1950’s there were many innovative designs for continuous welding that would provide the end user higher deposition rates. Unfortunately, most had flaws and were not commercially viable. It was not until around 1957 that the flux cored wire process as we know it today was first introduced to the market. The first flux cored wires were large diameter, 1/8” (3.2 mm) and 5/32” (4.0 mm) diameters. Back then, the 3/32” (2.4 mm) diameter was a “small diameter” flux cored wire. Flux cored wires provided better metal penetration, smoother arc transfers, lower spatter levels and were overall easier to use than solid MIG wires, but they were limited to flat and horizontal positions and the equipment to use them was heavy and cumbersome. As flux cored wires developed, smaller diameters began to emerge into the welding market, which led to the ability to weld in all positions. Advancements in equipment also made welding with flux cored wires more comfortable for the welder. Now for the first time, high deposition rates were obtainable in the vertical and overhead positions. Acid (rutile) slag systems gave high welder appeal, good mechanical properties and lent themselves to many applications formally welded with the MIG or SAW process.

However, flux cored wire manufacturers and fabricators did not stop their developments and quest for a continuous process that was faster, better, and more economical. They needed to overcome one last hurdle, to achieve both high deposition rates or the amount of weld metal deposited per hour and high deposition efficiencies, how much of the welding consumable becomes part of the weld deposit. Could we reach the high productivity level of flux cored wires, but maintain the high deposition efficiencies of the solid MIG wire process? The answer came in the form of a fabricated composite cored wire known as the metal cored wire.

Metal cored wires are classified under the American Welding Society specification with solid MIG wires (AWS A 5.18-93 for mild steel, AWS A5.28-98 for low alloy and AWS A5.9-93 for stainless steel). Metal cored wires will carry the same basic classification for strength level and chemical composition as solid MIG wire but are denoted by a “C” for composite wire. For example, a 70 KSI metal cored wire having a chemical composition and mechanical properties like an E70S-6 solid wire would be classified as an E70C-6 composite wire. Considered to have some characteristics like flux cored wires and other characteristics like solid wire, metal cored wires do share a similar construction to flux cored wires and performance like solid MIG wires.

The outer metallic sheath of a cored wire conducts the electrical current for welding. Because of the fabricated, composite nature of cored wires, their current carrying density is greater, which improves deposition rates at equal current levels when compared to solid MIG wires.

The internal components of a metal cored wire are composed mainly of the alloys, manganese, silicon, and in some cases, nickel, chromium, and molybdenum as well as very small amounts of arc stabilizers such as sodium and potassium, with the balance being iron powder. Metal cored wires provide the benefit of being able to have alloy compositions formulated for specific applications in smaller batches than the normal large heats of solid wire. Many alloy compositions employing chromium, nickel and molybdenum are now available including austenitic and ferritic stainless-steel alloys. Metal cored wires have little to no slag forming ingredients in the internal fill of the wire. Just like solid MIG wire, welds made with a metal cored wire will only have small silicon islands from the deoxidized products that appear on the surface of the weld. This allows for multiple pass welding without de-slagging.

So, how do metal cored wires fit into a particular welding application? When is a metal cored wire the correct choice? What are the factors that need to be considered in choosing a metal cored wire? Do metal cored wires really offer that much benefit over flux cored wires or solid MIG wires? When making a major process change in the welding of an application, it is normal to ask a lot of questions. The whole process can become a bit overwhelming to the point that no decision is made. To prevent that from happening, we will look at both the advantages and possible disadvantages of using metal cored wires.

High deposition efficiency

Whenever a weld is made, a percentage of the welding consumable is lost to slag, spatter, and fume. Deposition efficiency relates to the amount of a consumable that becomes deposited weld metal. The higher the deposition efficiency of a consumable, the lower the amount of that consumable is wasted by not becoming part of the deposited weld metal. Because of the characteristics of a flux-cored wire and slag covering the molten weld puddle, they are efficient in the range of 84-89% dependent upon the diameter and slag volume of the wire design. Solid MIG wires are highly efficient based on virtually non-existent slag. Solid MIG wires will typically exhibit efficiencies in the range of 95-98% depending upon the mode of the transfer used. Deposition efficiency is a true “spray” transfer under high argon shielding gas mixtures that will yield the highest deposition efficiency. Metal cored wires with their arc characteristics being like solid MIG wires and very low spatter level as well as low slag volume, also exhibit deposition efficiencies in the 92-98% range with the selection of spray transfer mode and high argon shielding gas mixtures. When solid wires are used in the “short arc” transfer mode or with higher carbon dioxide content shielding gas, some deposition efficiency will be lost due to the increased spatter level. This is also true with flux cored and metal cored wires. Changes in transfer mode and shielding gas will influence the deposition efficiency. In some high-speed applications, solid MIG wires are used at lower voltages to avoid a large spray column. Using a solid MIG wire at voltages that produce a high spray column could produce undercut and underfill, and can prevent the high travel speeds required for productivity. This practice produces a higher level of fine spatter, which decreases the deposition efficiency of the wire. When the same practice is used with metal cored wires, the level of fine spatter is greatly reduced. Along with obtaining a better deposition efficiency, maintenance costs for tooling and equipment can be lower.

Deposition rates

The deposition rate of a welding consumable is the measurement of how much weld metal is deposited within a given period. Deposition rates along with deposition efficiency are the leading determinants of the cost effectiveness of a consumable. Generally expressed as pounds per hour (kg. /hr) flux cored and metal cored wires have some of the highest deposition rates of all of the welding consumables. Flux cored and metal cored wires are capable of having deposition rates as high as 12-14 pounds per hour (5.4-6.4 Kg/hr) for a 0.045” (1.2mm) diameter wire. This compares to a solid MIG wire in the same diameter of 8-10 pounds per hour (3.6-4.5 Kg/hr). The high deposition rates coupled with high deposition efficiencies and low slag volume will allow the metal cored wire to be used at higher travel speeds resulting in increased productivity. A general rule of thumb that has been used is that when a deposition rate of 9 pounds per hour or greater is achieved with a metal cored wire versus a solid MIG wire, the economics of the weld will show a cost saving in favour of the metal cored wire.

High duty cycles & high travel speeds

Any continuous welding process will inherently have a higher duty cycle, or the amount of continuous arc time, this makes sense. The SMAW process of stick electrodes requires the welder to stop in short intervals of the weld to de-slag and change electrodes. The duty cycle for SMAW electrodes is in the range of 20%. This translates to only 12 minutes of welding every hour an arc is generated. With a continuous process such as cored wire or solid MIG wire, the duty cycle increases to as much as 50% of the time or 30 minutes per hour for arc generation. This is one factor that makes the use of automated or robotic welding so attractive, the ability to use a continuous process. Along with the increase in duty cycle comes the benefit of faster travel speeds. Automated welding is only limited to the supply of parts to the weld station and the travel speed of the process. Solid MIG and flux cored wires can contribute to the higher duty cycles, but only metal cored wires have the capability of combining high duty cycles with high travel speeds to exploit these factors without sacrificing bead appearance, penetration, and weld integrity. Increases in travel speed of 35-40% are not unrealistic when converting from a solid MIG wire to a metal cored wire. Increased duty cycles and higher travel speed can significantly reduce the cost of welding. Fabricators who for the first time use a metal cored wire in an automatic application are often surprised at the ability to increase in travel speed while maintaining weld integrity and bead appearance.

Low slag volume & low spatter levels

Coupled with increase duty cycle of a consumable is the decrease in removing slag from the weld. This is one of the biggest advantages solid MIG wires has over flux cored wires. Because of the compositional characteristics of the metal cored wires, they also have a very low slag volume like solid MIG wires. The advantage of metal cored wires comes in decreased spatter levels that need to be cleaned from the parent material prior to finishing. In many cases, the small silicon islands formed on the weld are easily removed. Metal cored wires tuned to the proper welding parameters and using high argon mixes for shielding gas will also have a decrease in the amount of spatter.

This is especially an advantage to continuous operations where the part moves from an assembly/welding operation directly into a cleaning and painting operation. Cleaning of weld spatter from a fabricated piece can cost significantly in post weld clean up. One particular application in which this was evident was in a mobile crane manufacturer who went from a basic slag flux cored wire to a metal cored wire and saved an average of 12-14 man hours per unit in post weld cleaning prior to painting. Metal cored wires has the advantage of having arc stabilizers in both the internal components as well as applied to the surface of the wire. The arc stabilizers enhance the arc characteristics as well as minimize the spatter levels.


The real payback for any change in process or welding consumable comes with the economics of the change, how can we do it better, but at a lower cost per unit. A common mistake is to try to obtain the incumbent filler metal at a lower price. Because the actual cost of the filler metal for welding is a small percentage of the total, maximum savings are not achieved. When breaking down the actual cost per pound for a deposited weld, the cost of the filler metal only contributes approximately 15% of the total cost. Other factors such as labour, overhead, equipment, electrical cost, deposition efficiency and deposition rates of the filler metal can have a much larger impact. Bottom line with a filler metal is that it’s not how much it costs per pound that counts, but how much it costs per pound to use. An analogy to this would be in purchasing paint. Take one brand that costs £10 per gallon versus another brand that cost £20 per gallon. If the lower priced paint takes additional coats for coverage and does not cover the same square footage per gallon, any savings in the purchasing price is lost. The same can be true of choosing the correct filler metal to maximize the cost per pound of deposited weld metal.

Consider an actual application using 0.052’ (1.4 mm) E70S-6 MIG wire welded under pulse conditions at 425 inches per minute wire feed speed, 24.5 volts and travel speed of 70 inches per minute. This was converted to metal cored wire welded and at the same wire feed speed, voltage, and travel speed. Because of the benefits of the metal cored wire, the travel speed could be increased to 85 inches per minute, or a 20% increase. Not only did the travel speed rise, increasing the through put, but the number of necessary repairs also diminished as did the amount of time to make repairs by 10%. Because the line time cost was calculated in pounds per minute, a huge saving in real pounds was realized from even small advances in productivity improvement. The cost per pound for the metal cored wire was more than the cost per pound for the solid MIG wire, but the realized savings more than offset any additional cost for the metal cored wire.

In another application, a 0.040” diameter (1.0mm) ER409Cb solid MIG wire was welded under pulse conditions at 180 amps, 20 volts and 19.6 inches per minute travel speed for a thin wall tube. Conversion to an 0.045” (1.2 mm) EC409Cb metal cored wire welded under pulse conditions at 190 amps, 21 volts and 27.5 inches per minute travel feed speed. Not only did the travel speeds increase, but an additional advantage was seen in the ability of the metal cored wire to bridge gaps due to poor fit up. This also contributes to a lower defect rate and the need to rework parts offline. The results were on average, a 40% increase in production, lower consumable cost per pound of weld metal and lower maintenance cost.

Disadvantages to metal cored wires

So far, we have weighted to show the advantages of converting solid MIG wires or flux cored wires to a metal cored wire, but there are disadvantages as well. To gain the fullest potential benefit from using a metal cored wire, an automated or robotic set up is required. Expecting the maximum potential increase in travel speed to be met and consistently maintained in a handheld operation is expecting a lot from a welder. Automated systems are consistent and don’t tire nor do they need breaks. If a continual supply of parts is supplied, an automated system keeps on working. If a current application is being managed only by handheld welding stations, a capital investment would need to be made in an automated system. Repetitiveness of an application is necessary to minimize set up and jig costs. Experience in programming a robot is necessary due to an increase in weld puddle fluidity. Such would be the case in welding a small diameter tube where the positioning of the torch to the part is more sensitive with a metal cored wire. The cost of the automated system must be considered also as well as the ability to provide a reasonable payback on the investment.

To obtain a spray transfer, which is the best mode to provide excellent wetting in of the bead and to minimize spatter, high argon gas mixtures are required. Although high percentages of argon in the shielding gas reduce fume generation these types of shielding gases also generate more heat and higher amounts of radiant light. Water cooled welding guns and protection from not only the arc, but also reflected light are essential for a safe workplace. This is another reason automated systems help in maximizing the benefits of metal cored wires. They are not as susceptible as a welder to the effects of the additional heat and radiant light generated.

To gain all position capability with a metal cored wire, like the solid MIG wires, either a short arc transfer mode or pulse mode is required. Short arc would be eliminated due to the significant drop-in deposition rate, deposition efficiency and increase in spatter. Most pulse machines do not contain a program specifically for metal cored wires. Although not necessary, the development of a synergic curve and pulse parameters does enhance the performance of a metal cored wire. If existing equipment is not able to pulse or does not have a pulse program specifically for metal cored wires and the desire to enhance the arc and operability is there, the equipment manufacturer will have to adjust and program modification to the power source. Depending upon the machine manufacturer, these adjustments may be able to be made to the current power sources.

A significant increase in productivity and through put in one station will be negated if the subsequent stations down the line cannot handle the additional parts. It wouldn’t be an advantage to increase productivity by 30-40% in a weld station if it’s only operated 50-60% of the time due to parts backing up. Payback on the investment would be extended to the point of being unattractive to most. When considering the increase in parts per hour that can be achieved from changing to the higher productivity metal cored process, the stations down the line from the operation also need to be considered as far as their capability of handling the increase from productivity gains.


The industry to a large extent still views metal cored wires as being somewhat marketing smoke and mirrors. It’s sometimes very hard to understand how a product that has a greater cost per pound than a filler metal will actually save money when evaluated as cost per pound deposited, or the true cost for the welding application. It’s not until actual results are obtained that the reality of what can be achieved is believed. It’s human nature to believe what is in front of our eyes rather than what someone is promoting today. Trying metal cored wires in your application could result in significant improvement in productivity. Evaluating the total picture should result in being able to identify specific benefits over the consumables that may be currently being used. Among these benefits, which translate into cost savings, are high deposition rates, high deposition efficiencies, high duty cycles, high travel speeds, low slag volume and low spatter. In addition, the newer technology offered by manufacturers would give the operators the added benefit of lower fume generation rate for a safer, healthier weld environment. Metal cored wires can be a benefit regardless of whether they’re used in a handheld operation or in an automated weld station. From handheld to simple automation to a full multi-process robot, metal cored wires can and do offer benefits over other choices in consumables.

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Company Registration: 07988136 Registered Office: Olympic House, Collett, Southmead Park, Didcot, Oxfordshire, United Kingdom, OX11 7WB


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