Nozzle

Features Equipment
Cored wires, as a result of their superior deposition rates, enable the Power sources
fabricator to achieve genuine savings in welding times and hence Standard production MIG rectifiers are suitable for operating cored

Contact tip
labour costs. Increased sidewall penetration is another major process wires provided they have sufficient current capacity to match the
attribute, often leading to further economies. Additional benefits are amperage specified for a given size of wire. In addition the power
outlined below. source should have an appropriate duty cycle compatible with the
component being welded.

Flux core
Flux Cored Wires Wire Feeders
All-position capability The efficient feeding of cored wires will depend on the type of feed rolls
Good slag removal characteristic used. While 1.0mm, 1.2mm and 1.4mm cored wires are satisfactory
Low hydrogen levels when used in conjunction with a grooved drive roll and flat pressure roll,
Ideal for Use with Ar/20%CO2

Metal tube
it is recommended that geared and knurled feed rolls should be used
Able to deal with heavy rust and scale for the larger sizes on both single and tandem systems.
Produce a consistent level of mechanical properties

Arc
Torches

Shielding gas
Careful consideration should be given to the torch selected relative to

Slag
Metal Cored Wires wire diameter, proposed current level and duty cycle. In certain
High metal recovery (up to 95%) circumstances water cooling Is required e.g. for 1.6mm and larger
No inter-run de-slagging

Weld pool
diameter wires at high currents and high duty cycles.
Good weld appearance Shielding gases
Tolerant to variations in welding current With the exception of Corofil R58, which is designed for use with CO2,

Workpiece
Caters for majority of downhand applications at one current setting the flux cored wires can be used with either Ar + 15/20% CO2 gas
mixtures or in some cases CO2 gas. For optimum mechanical
Self Shielded or Gasless Wires properties, careful selection of an appropriate shielding gas is
No gas shield required
recommended, and advice should be sought from your gas supplier or
Good on-site accessibility
direct from Murex. The metal cored wires must always be used with Ar
+ 15/20% CO2 mixtures as the use Of CO2 will result in a serious
WARNING: Adequate safety precautions must be taken to offset the effect of heat, glare and fumes deterioration in weld appearance and the degree of fume and spatter
will be excessive. Coromig 58 has also been designed to run on CO2

Applications gas for single pass fillet welding. A flow rate of 15/20 litres per minute
should be maintained at the torch nozzle.
Consumables are available for use in numerous applications. Some
typical applications are given below. Contact your nearest Murex
distributor for details of selection to meet specific requirements.
What is Cored Wire? Polarity
DC electrode positive polarity is recommended for the Corofil rutile flux
cored wires since the use of the negative pole produces inferior running
characteristics and can occasionally produce porosity.
Flux Cored Wires A cored wire is formed by filling a U shaped metal strip with flux and/or metal powder, and The Coromig metal and basic flux cored wires on the other hand,
General fabrication of mild steel benefit from the use of DC electrode negative polarity giving an
drawing it out into a filled tube. In simple terms therefore this process produces an inside
General fabrication of medium steel under conditions of improved arc action and weld finish with a reduction in spatter.
high restraint. out covered welding rod with the flux material concentrated in the heart of the arc. Amperage
All-positional welding With flux cored wires the amperage used is ideally in the top half of the
Heavy deposition in downhand butt and flat or HV fillet joints The MUREX cored wire range is designed to provide the fabricator with a selection of range specified for a particular size except when positional welding with
Positional welding of structural work for service down to -60C. 1.0mm, 1.2mm, 1.4mm, and 1.6mm wires, when the dip transfer mode
Welding of stainless steels
wires to meet a wide range of applications at welding speeds up to three times faster is used at current below 220 amps. Coromig metal cored wires
eliminate the need for current variations relative to plate thicknesses
than manual metal arc electrodes. since one current setting for a given wire size will cater for 90% of flat &
Metal Cored Wires
HV applications. The weld cross-section is controlled by the travel
General fabrication of mild steel Cored wires are available for general purpose, high productivity welding, critical speed whereas solid wire would require considerable current re-setting
General fabrication of medium tensile steel to achieve the same flexibility.
Welding of high tensile as well as quench and tempered steels structures and pressure vessels, where good mechanical properties plus notch
Fabrication of mild and medium tensile steels with provision for
Voltage
weathering qualities when welding CORTEN A & B steels
toughness are required. In addition a range of wires for hard surfacing is also available. Arc voltage has a direct influence on the arc length which controls the
weld shape, depth of penetration and spatter level. As the arc voltage is
Structural steelwork and offshore structures for service down reduced the penetration increases and this is particularly important in V
to -50C. High deposition rates butt joints.
High quality weld metal properties An increase in voltage will result in a long arc length and increase the
Increased penetration compared to solid wire
Self Shielded or Gasless risk of porosity and undercut.
Hard surfacing of worn components When operating on dip transfer for positional welding at comparatively
Buffering layers Lower incidences of rejects, resulting in lower total fabrication costs low currents the arc voltage should be kept at the highest
Positional welding capabilities
practicable level to ensure adequate side wall fusion.

MUREX manufacture two ranges of cored wires: Corofil Flux cored and Coromig metal cored.
Welding Technique Torch Angles
Plate Preparation Corofil Flux cored wires Flux Cored Wires
Due to superior side wall fusion obtained particularly from the metal The Corofil flux cored wire range is divided into two types, Rutile (R) and Basic (B) each producing a stable arc, easy slag With Corofil flux cored wires the torch angle has a significant effect on
cored wires the combined angles of preparations can generally be slag control and weld deposit profile. For both fillet and butt joints the
reduced. A V-Butt joint for instance that would normally need a 60 removal, good appearance, plus a high recovery of approximately 90%. Corofil flux cored wires can be used with argon rich
recommended angle between the wire axis and the line of joint is
included angle for manual arc welding can be reduced to 45 thereby shielding gases with a CO2 content of 15-25% and some with CO2 and are recommended where high quality is required. between 60-70 and using a backhand technique i.e. pulling, with the
saving plate and hence weld metal to fill the joint. Cored wires have a wire pointing toward the completed weld. In this way the arc force
higher level of deoxidents than solid wires and normally operate at prevents the slag from running in front of the weld pool and reduces
higher current densities. This facility allows them to be used where light Coromig Metal cored wires the risk of slag traps. For HV fillets the wire tip should be directed
mill scale and primer have to be tolerated. For optimum radiographic toward the bottom plate at approximately 3mm from the line of the
standards with flux cored wires excessive rust and scale should be
The Coromig range of metal cored wires represent a novel concept in cored wire welding. Utilising a metal powder core and
joint with a torch angle of 45 from the vertical plate.
removed by grinding which will also serve to reduce slag formation to argon rich shielding gases, Coromig wires offer exceptionally fast welding speeds and deposition efficiency. Welding is
a minimum when using the metal cored wires. particularly smooth and almost spatter-free with a minimum of slag, and with fume levels comparable to those of solid wire
MAG welding. In addition Coromig 58 can be run on CO2 shielding gas for single pass fillet welds.
Developed to meet a wide range of welding applications Coromig wires are available for high speed general purpose, low 45 o

60 o 50 o temperature and high strength requirements. 60-70o

70 o
90 o
Torch angles and manipulation
Vertical but welds Vertical fillet welds
1st pass
Electrode extension (no weaving)
This term describes the distance between the contact tip of the torch
In certain circumstances the forehand technique i.e. pushing, can be
and the workpiece, sometimes described as electrode stickout.
used to advantage. On small fillet welds where penetration is not of
The current conditions should be set for the job in hand but during
welding it may be necessary to reduce the amount of heat in the paramount importance the higher welding speeds required are such
weld pool to accommodate poor fit-up or out of position welding. that the molten slag is prevented from running ahead of the weld pool.
An increase in the stickout length and the extra electrical resistance that This also has the advantage of producing a mitre fillet where as the
results will produce a cooler less fluid weld pool. Similarly any decrease backhand method tends to produce a more convex profile.
in electrode extension will have the effect of increasing welding current Metal Cored Wires
and this characteristic can be of benefit in controlling penetration Maximum penetration is obtained using a backhand (pulling) technique
especially where inconsistent fit-up is encountered. with a torch angle of 70/80 between the wire axis and the joint line.
10 o This will also serve to optimise gas coverage and is particularly relevant
to multipass butt welds.
10/20 o
Metal cored wire
1st pass Fill & Cap Fill & Cap
Single pass 10/20 o
10o 70 o
90 o

Preparation with root face Preparation with feather edges Triangular weave for single pass fillets. If necessary Restrict vertical down technique to thin plate or leg
Contact tip subsequent weld runs should be deposited using lengths of 6mm maximum. May be used for first pass
Contact tip protrudes from technique similar to that for filling vertical butt joints. No of multi pass joints
within nozzle shorter nozzle weaving is necessary for single pass fillets when using
Corofil R56XL.
Stickout length Stickout length
45 o
Spray transfer Dip transfer 70 o
bottom of deep grooves to allow for easier access whilst maintaining Positional Welding
the required stickout. In order to observe the weld pool and maintain a All the 1.0mm, 1.2mm and 1.4mm metal and flux cored wires are ideally
stable arc when using dip transfer a short shroud is recommended. suited to positional welding of open butt and fillet joints. Root runs in
When operating with dip transfer a stickout length of 12mm will suffice In this case the contact tip will extend beyond the shroud by 4/5mm. butt welds with rutile wires require ceramic backing tiles.
for most applications, where as spray transfer produces a greater Butt Welds
Travel Speed
amount of radiated heat and should have an extension of approximately For vertical open butt welds requiring complete root penetration both the
Travel speed has an important influence on penetration. For example
25/35mm. During actual welding any large variation in stickout length vertical up or vertical down technique can be used for root passes. When
when using a 1.6mm metal cored wire at 350A an increase in travel 45 o
produces an inconsistent weld deposit and excessive stickout will filling and capping butt welds in the vertical position the vertical up method
speed from 30cm/min to 60cm/min approximately doubles penetration
reduce the effectiveness of the gas shield. For a given wire feed rate an is preferred using triangular or single weave patterns. Here again, where low 60 o
beyond the root of the fillet.
extension of the stickout has the effect of reducing the amperage drawn temperature impact properties are required, care should be taken to minimise
At speeds in excess of 80-100cm/min penetration will decrease.
from the power source. Therefore, increasing the wire feed speed to the cross section of individual beads. Savings can be made in plate penetration
Similarly a reduction in penetration will occur if the welding speed
compensate for the current drop, will result in a significant increase in costs with Coromig metal cored wires as a uniform bead of penetration is
should fall to below 30cm/min, as the arc can impinge on the molten
metal deposition. For example, a 1.6mm metal cored wire at 400A using possible without root faces when the vertical down technique is employed.
pool in preference to the base material.
a stickout of 30mm will achieve a deposition rate of 9kg/hr as compared Fillet Welds
In addition the use of slow travel speeds should be avoided when low
with 8kg/hr at the same current with a stickout of only 10mm. Fillet joints may be welded using either the vertical-up or vertical-down
temperature impact properties are required. While the joint may be
Gas Shroud filled in fewer passes the individual weld deposits will be of large techniques. The choice will depend on the thickness of material being For fillet and lap welds superior weld appearance is achieved
To ensure adequate gas coverage when using spray transfer a long cross-section and therefore impact resistance will be reduced. Apart welded and degree of root penetration specified. Multi-pass fillet welds using a torch angle of 60/70, and a forehand technique (pushing).
shroud should be used and will extend beyond the contact tip by about from this, in the case of flux cored wires, there is the obvious difficulty should be completed on a similar basis to that of butt welds using the CORED WIRE
This results CORED WIRE
in a more even distribution of weld metal,
6mm. However, a short shroud may be necessary when welding in the of slag control to be considered. vertical up technique. accompanied by a slight reduction in penetration.

Murex Welding Products offer a comprehensive range of:

www.murexwelding.co.uk
Arc Welding & Cutting Equipment
Gas Welding & Cutting Equipment CORED WIRE CORED WIRE
Welding Consumables & PPE Welding Accessories
For full details visit the Murex website: