Friday, March 4, 2011

RE: [MW:10135] Can I use E 7018 in Pipe root runs? Wats the disadvantages?

Hi All,

6010 bieng cellulosic electrode has a high arc force,which makes it more penetrating and therefore used for root
7018 is a basic electrode which gives better strength to the weld so to have better pen we need to use 6010 for root

--
With Warm Regards,
Prakash Verma
Metallurgist-Drilling Riser Systems
QS Supply Chain.
Aker Solutions Supply chain hub-India
AkerSolutions
Tel.+91-20-66 28 8538
Email. prakash.verma@akersolutions.com


-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of krishnasamy masanam
Sent: Thursday, March 03, 2011 8:27 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:10124] Can I use E 7018 in Pipe root runs? Wats the disadvantages?

Dear Friend!
E 7018 is best for weld deposit. you can weld with E 7018 but the root penetration will not be sufficient. for your help just read the follwoing items. It might be help for you.

saamy

Welding consumables - Part 1
Part 2
Part 3
Part 4
Part 5
The next series of Connect articles will cover welding electrodes and filler metals, beginning with a brief look at the requirements for a flux. Whether a flux is in an electrode coating or is in granular form, as in a submerged arc flux, the requirements are the same.
* The flux must be capable of providing a protective shield to prevent
atmospheric contamination of the electrode tip, the filler metal as it is transferred across the arc and the molten weld pool. Generally, it does this by decomposing in the heat of the arc to form a protective gaseous shield.
* It must be capable of removing any oxide film (failure to do so will
result in lack of fusion defects and oxide entrapment). It does this by reacting chemically with the oxide.
* It should improve mechanical properties by providing clean, high
quality weld metal and perhaps by transferring alloying elements across the arc.
* It must be capable of providing the desired weld metal composition,
again by transferring alloying elements across the arc.
* It should aid arc striking and arc stability.
* It should produce a slag that will shape the molten pool and hold
the pool in place during positional welding if required.
* Any slag should be readily removable and preferably self-detaching.
* It should not produce large amounts of fume and any that it does
should not be harmful to the welder.
These requirements have resulted in a multitude of different consumables, many being apparently identical, and this can make filler metal selection a difficult and confusing task. This article attempts to give some insight into the various types of flux coated manual metal arc (MMA) electrodes before moving on in later articles to look at other types of welding fluxes.
Most MMA electrodes can be conveniently divided into three groups by their coating composition. These are cellulosic, rutile and basic coatings, each of which gives the electrode a distinctive set of characteristics.
Cellulosic electrodes contain a large proportion of cellulose, over 30% and generally in the form of wood flour. This is mixed with rutile (titanium dioxide, TiO2 ), manganese oxide and ferro-manganese and is bonded onto the core wire with sodium or potassium silicate. Moisture content of these electrodes is quite high, typically 4 to 5%. The cellulose burns in the arc to form a gas shield of carbon monoxide, carbon dioxide and, in conjunction with the moisture in the coating, produces a large amount of hydrogen, typically 30 to 45ml hydrogen/100gm weld metal.
The hydrogen raises arc voltage and gives the electrodes their characteristics of deep penetration and high deposition rates. The high voltage requires a high open circuit voltage of around 70 volts to allow easy arc striking and to maintain arc stability. The forceful arc also results in appreciable amounts of weld spatter and this limits the maximum current that can be used on the larger diameter electrodes. A thin, friable and easily removed slag is produced, giving a rather coarsely rippled weld profile. The slag is also fast freezing so that, unlike most other electrodes, they can be used in the vertical down position - 'stovepiping'.
Electrodes with a sodium silicate binder can be used only on DC electrode positive (reverse polarity). Those with a potassium silicate binder can be used either DC electrode positive or on AC. The electrodes require some moisture in the coating to aid the running characteristics and they must never be baked, as may be done on basic coated electrodes. This has the advantage that the electrodes are tolerant to site conditions. If they become damp, drying at a temperature of around 120°C will be sufficient.
Electrode compositions are only available for welding low carbon non-alloyed steels although nickel additions may be made to improve notch toughness. Charpy-V values of around 27J at -20°C are possible in the unalloyed electrodes. The high hydrogen level means that any steel welded with these electrodes should be selected to have a very high resistance to hydrogen induced, cold cracking (see Connect articles numbers 45 and 46). They should not be used without giving due consideration to the steel composition, restraint and the need for preheat. The characteristics of deep penetration, high deposition rates and the ability to be used vertically down means that the main use for these electrodes is for cross country pipelining although they are used to a more limited extent for welding storage tanks.
Rutile coatings, as the name suggests, contain a large amount of rutile, titanium dioxide, typically around 50%, in addition to cellulose, limestone (calcium carbonate), silica (SiO 2 ) mica (potassium aluminium silicate), ferro-manganese and some moisture, around 1 to 2%. Binders are either sodium or potassium silicate. The cellulose and the limestone decompose in the arc to form a gas shield containing hydrogen (around 20ml/100gm weld metal) carbon monoxide and carbon dioxide. The electrodes have medium penetration characteristics, a soft, quiet but stable arc and very little spatter, making them a 'welder friendly' electrode. Striking and re-striking is easy and the electrodes will run on very low open circuit voltages.
The electrodes produce a dense covering of slag that is easily removed and gives a smooth evenly rippled weld profile.
The presence of cellulose and moisture means that the electrodes produce relatively high levels of hydrogen, perhaps 20 to 25ml/100gm weld metal. This restricts their use to mild steels less than 25mm thickness and thin section low alloy steels of the C/Mo and 1Cr1/2Mo type. Mechanical properties are good and Charpy-V notch toughnesses of 40J at -20°C are possible. They are probably the most widely used general purpose electrode. Rutile coated austenitic stainless steel electrodes can be obtained and can be used in all thicknesses as cold cracking is not a problem with these alloys.
Rutile electrodes, like cellulosic electrodes, require some moisture in the coating and they should not be baked. If they become damp, re-drying at around 120°C should be sufficient. Those electrodes with a sodium silicate binder can be used on DC electrode negative or AC.
Electrodes with the potassium silicate binder can be used on both polarities and on AC. The potassium silicate binder electrodes generally have better arc striking and stability characteristics than the sodium silicate binder types and a more readily detachable slag.
The next article will look at the basic, low hydrogen electrodes and some of the other less common types of coatings.
This article was written by Gene Mathers.
Copyright © 2010 TWI Ltd
Information and advice from TWI and its partners are provided in good faith and based, where appropriate, on the best engineering knowledge available at the time and incorporated into TWI's website in accordance with TWI's ISO 9001:2000 accredited status. No warranty expressed or implied is given regarding the results or effects of applying information or advice obtained from the website, nor is any responsibility accepted for any consequential loss or damage.

Part 2
Welding consumables - Part 2
The previous article, Part 1, dealt with the cellulosic and rutile electrodes. This article will cover the basic, iron powder and acid electrodes.
The description 'basic' originates from the chemical composition of the flux coating which contains up to perhaps 50% of limestone, calcium carbonate (CaCO 3 ). This decomposes in the arc to form a gas shield of carbon monoxide/dioxide.
In addition to the limestone there may be up to 30% of calcium fluoride (CaF 2 ) added to lower the melting point of the limestone and to reduce its oxidising effect. Also deoxidants such as ferro-manganese, ferro-silicon and ferro-titanium are added to provide de-oxidation of the weld pool.
Other alloying elements such as ferro-chromium, ferro-molybdenum or ferro-nickel may be added to provide an alloy steel deposit. Binders may be sodium silicate, only for use on DC+ve current, or potassium silicate which enables the electrodes to operate on both direct and alternating current.
The gas shield from basic electrodes is not as efficient as that from the rutile or cellulosic types and it is necessary to maintain a constant short arc if porosity from atmospheric contamination is not to be a problem. The electrodes are particularly sensitive to start porosity because of the length of time taken to establish an efficient protective shield. An essential part of welder training is familiarisation with the technique of starting the weld ahead of the required start position and moving back before proceeding in the direction of welding.
The penetration characteristics of basic electrodes are similar to those of rutile electrodes although the surface finish is not as good.
The slag cover is heavier than rutile electrodes but is easily controlled, enabling the electrodes to be used in all positions. High limestone coatings have been developed that enable a limited range of electrodes to be used in the vertical-down (PG) position. The weld pool blends smoothly into the parent metal and undercutting should not occur.
The slag is not as easily removed as with rutile or cellulosic electrodes but the low melting point means that slag entrapment is less likely. The chemical action of the basic slag also provides very clean, high quality weld metal with mechanical properties, particularly notch toughness, better than that provided by the other electrode types. A further feature of these electrodes is that the welds are more resistant to solidification cracking, tolerating higher levels of sulphur than a rutile or cellulosic electrode. This makes them valuable if it becomes necessary to weld free cutting steels.
The basic electrode is also known as a low hydrogen rod ('lo-hi'). The coating contains no cellulose and little or no moisture provided the electrodes are correctly handled. When exposed to the atmosphere, moisture pick-up can be rapid. However, baking the electrodes at the manufacturers' recommended baking temperature, generally around 400°C, will drive off any moisture and should provide hydrogen levels of less than 5ml/100g weld metal. After baking the electrodes need to be carefully stored in a holding oven at a temperature of some 120°C to prevent moisture pick-up.
Many manufacturers now provide electrodes in hermetically sealed vacuum packs with hydrogen levels guaranteed to be less than 5ml/100g weld metal. These are particularly useful in site applications where there is a need to maintain very low hydrogen levels and baking and storage facilities are not available. The electrodes are taken directly from the pack and can be used for up to 12 hours from opening before sufficient moisture has been absorbed to require baking.
Basic, low hydrogen electrodes are therefore widely used in a variety of applications where clean weld metal and good mechanical properties are required. They can be obtained with alloyed core wires and/or ferro-alloy additions to the coating to give very wide selection of weld metal compositions, ranging from conventional carbon steels, creep resistant and cryogenic steels and duplex and stainless steels.
Where high quality, radiographically or ultrasonically clean weld metal is a requirement, such as on offshore structures and pressure vessels, basic electrodes will be used.
Developments over the last 20 or so years have enabled carbon-manganese steel consumables to give good Charpy-V and CTOD values at temperatures down to -500C. The low hydrogen capabilities also mean that basic electrodes would be used for the welding of thick section carbon steels and high strength, high carbon and low alloy steels where cold cracking is a risk (see Job knowledge articles Nos.
45 and 46).
In addition to the 'standard' cellulosic, rutile and basic electrodes discussed above, electrodes may be classified as 'high recovery'.
By adding substantial amounts of iron powder, up to 50% of the weight of the flux coating, to either basic and rutile electrode coatings it is possible to deposit a greater weight of weld metal than is contained in the core wire. These electrodes are described as having an efficiency above 100% eg 120%, 140% etc and this 3 digit figure is often included in the electrode classification.
The electrodes have thicker coatings than the 'standard' electrodes which can make them difficult to use in restricted access conditions.
They are, however, welder friendly with good running characteristics and a smooth stable arc. The iron powder not only melts in the heat of the arc to increase deposition rate but also enables the electrode to carry a higher welding current than a 'standard' electrode.
The iron powder is electrically conducting, so allowing some of the welding current to pass through the coating. High welding currents can therefore be used without the risk of the core wire overheating, thus increasing both the burn-off and the deposition rates. The high recovery electrodes are ideally suited for fillet welding, giving a smooth, finely rippled surface with a smooth blend at the weld toes.
They are generally more tolerant to variations in fit-up and their stability on low open circuit voltages means that they are very good at bridging wide gaps. However, the large weld pool means that they are not suited to positional welding and are generally confined to welding in the flat (PA) and horizontal-vertical (PC) positions.
The last type of electrode covering is described as 'acid'. These electrodes have large amounts of iron oxides in the flux coating which would result in a high oxygen content in the weld metal and poor mechanical properties. It is therefore necessary to incorporate large amounts of de-oxidants such as ferro-manganese and ferro-silicon in the flux. Although they produce smooth flat weld beads of good appearance and can be used on rusty and scaled steel items the mechanical properties tend to be inferior to the rutile and basic coated electrodes. They are also more sensitive to solidification cracking and are therefore little used.
The next articles will cover specification and classification of MMA
(SMAW) electrodes.
Part 3
Part 4
Part 5
This article was written by Gene Mathers.
Copyright © 2006 TWI Ltd
Information and advice from TWI and its partners are provided in good faith and based, where appropriate, on the best engineering knowledge available at the time and incorporated into TWI's website in accordance with TWI's ISO 9001:2000 accredited status. No warranty expressed or implied is given regarding the results or effects of applying information or advice obtained from the website, nor is any responsibility accepted for any consequential loss or damage.

Part 3

Welding consumables - Part 3
Part 1
Part 2
Part 4
Part 5
The last two articles covered the various types of manual metal arc consumables that are available.
In order to be able to specify the type of flux coating, welding characteristics and chemical composition of an electrode for a particular application, there needs to be some standardised method of unique identification that is universally recognised.
This requirement has led to the writing of a series of consumable specifications that enable an electrode to be easily and uniquely identified by assigning a consumable a 'classification'. The two MMA electrode classification schemes that will be dealt with in this month's article are the EN (Euronorm) and the AWS (American Welding
Society) specifications. There is insufficient space to cover in detail the whole range of compositions for MMA electrodes so the emphasis here will be on the carbon steel filler metals.
The European specification for non-alloy and fine grained steel MMA electrodes is EN 499. This divides the classification or designation number into two parts. Part 1 is a compulsory section that requires symbols for the process, strength and elongation, impact strength, the chemical composition and the type of flux coating. The second part is optional and includes that includes symbols for the type of current and metal recovery, the welding position(s) that the electrode can be used in and for the maximum hydrogen content of the deposited weld metal (NOT the electrode).
The designation of a covered electrode begins with the letter 'E'.
This tells us that this is a covered electrode intended for MMA welding. The next two numbers give the minimum yield strength that may be expected as shown in Table 1.
Table 1 Strength and elongation symbols
Symbol Min Yield Strength
N/mm Tensile Strength
N/mm Minimum
Elongation %
35 355 440 - 570 22
38 380 470 - 600 20
42 420 500 - 640 20
46 460 530 - 680 20
50 500 560 - 720 18
The next symbol indicates the temperature at which an average impact value of 47J can be achieved, as shown in Table 2.
Table 2 Impact value symbol
Symbol Temperature for
average of 47J °C
Z No requirement
A +20
0 0
2 -20
3 -30
4 -40
5 -50
6 -60
The third mandatory symbol is for the composition. Although the specification title (non-alloy and fine grained steels) suggests that the electrodes have no alloying elements present, up to 3% Ni and NiMo electrodes are included, see Table 3. (This symbol is only applied where the electrode contains 0.3Mo or 0.6Ni).
Table 3 Chemical composition symbols
Symbol Chemical composition % max or range
Mn Mo Ni
No symbol 2.0 - -
Mo 1.4 0.3 - 0.6 -
MnMo >1.4 - 2.0 0.3 - 0.6 -
1Ni 1.4 - 0.6 - 1.2
2Ni 1.4 - 1.8 - 2.6
3Ni 1.4 - >2.6 - 3.8
Mn1Ni >1.4 - 2.0 - 0.6 - 1.2
1NiMo 1.4 0.3 - 0.6 0.6 - 1.2
Z Any other agreed composition
The fourth symbol indicates the type of flux coating - basic, rutile etc as shown in Table 4.
Table 4 Symbol for flux coating
Symbol Coating
A acid
C cellulosic
R rutile
RR thick rutile
RC rutile-cellulosic
RA rutile-acid
RB rutile-basic
B basic
The next three symbols are not compulsory and give additional information on the percentage weld metal recovery and the type of welding current on which the electrode can be operated ( Table 5); the welding position ( Table 6) and the maximum hydrogen content of the deposited weld metal if the electrodes are dried or baked as recommended by the manufacturer ( Table 7).
Table 5 Symbol for weld metal recovery and current type
Symbol Weld metal recovery % Current type
1 <= 105 AC or DC+
2 <= 105 DC+ or DC-
3 >105<=125 AC or DC+
4 >105<=125 DC+ or DC-
5 >125<=160 AC or DC+
6 >125<=160 DC+ or DC-
7 >160 AC or DC+
8 >160 DC+ or DC-
Table 6 Symbols for welding position
Symbol Welding position
1 All positions
2 All positions except V-down
3 Flat butt and fillet welds, HV fillet weld
4 Flat
5 V-down, flat butt, flat and HV fillet welds
Table 7 Symbol for hydrogen content in weld metal
Symbol Max Hydrogen
ml/100gms weld metal
H5 5
H10 10
H15 15
A full designation may therefore read E42 2 B32H5. This describes a basic carbon manganese steel electrode; weld metal yield strength of 420N/mm2, better than 47J at -20°C, a weld metal recovery of over 105%, capable of being used on AC or DC+ current in all positions except vertical down and providing less than 5mls hydrogen in the weld metal.
The AWS specification equivalent to EN 499 is AWS A5.1 - Carbon Steel Electrodes for Shielded Metal Arc Welding. The classification comprises five characters but in the 2004 edition of the specification there are two separate schemes. A5.1, based on the US units of tensile strength in pounds per square inch, Charpy -V values in foot-pounds and A5.1M, based on the SI system, with strength in MPa, Charpy-V values in Joules.
It is thus possible to have virtually identical electrodes with different classifications, one using US units, the other SI units.
There is insufficient space within this brief article to describe fully all of the 18 types covered by the specification except perhaps for the most commonly used electrodes. For full details of the AWS scheme it is necessary to consult the specification.
To illustrate briefly how the electrodes are classified, the following gives a summary of the key features.
The first character 'E' is common to both classifications and indicates that the electrode is a flux coated manual metal arc electrode. The next two digits indicate the tensile strength. In the
A5.1 designation this is either '60', indicating a UTS of 60ksi and a yield strength of 48ksi, or '70', indicating a UTS of 70ksi and a yield strength of 58ksi. In the A5.1M designation these are 43 or 49, indicating a UTS of 430MPa, yield strength of 330MPa or 490MPa UTS, 400MPa yield respectively.
The last two digits give information on flux coating type, welding position, current type and polarity and Charpy-V impact strength, if required. Those electrodes suffixed XX10 or XX11 have cellulosic coatings; those suffixed XX12, XX13, XX14, XX19 or XX24 have rutile coatings and those suffixed XX15, XX16, XX18, XX28 and XX48 are basic low hydrogen. XX18, XX28 and XX48 all have iron powder additions and are therefore high recovery electrodes.
Listed below are those EN and AWS specifications that prescribe the requirements for ferrous electrodes.
BS EN 499 Non-alloyed and fine grained steel electrodes
BS EN 757 High strength steels
BS EN 1599 Creep resisting steels
BS EN 1600 Stainless and heat resisting steels
AWS A5.1/A5.1M Carbon Steel Electrodes for SMAW
AWS A5.4 Stainless Steel Electrodes for SMAW
AWS A5.5 Low Alloy Steel Electrodes for SMAW
This article was written by Gene Mathers.

Part 4

This article looks at the wire consumables used in the gas shielded MIG/MAG, metal cored (MC) and flux cored (FC) arc welding processes.
The MIG/MAG processes were first developed using a solid wire but some
25 years ago tubular wires began to be supplied and since then the use of these wires has grown rapidly and they now form a significant proportion of the welding wire market - cored wires are now used not only in the MIG/MAG process but also in TIG, plasma-TIG and submerged arc welding.
Solid wire for welding of alloy steels is an expensive commodity. The composition of a ferritic steel welding wire is not the same as that of the steel that it will be used to weld. The ingot from which the wire is drawn must contain all the de-oxidation and alloying elements that can be contained in the flux on an MMA electrode.
Steel is produced most economically in large tonnages whereas a consumable supplier requires only relatively small amounts and these requirements have a significant effect on the cost. In addition, it can be difficult to draw down the wire to the small diameters required for welding.
Cored wires for welding carbon and alloy steels, however, can be made from mild steel with the alloying elements added to the flux filling.
This enables small amounts of wire to be economically produced matching the composition of steels where the usage is limited, eg high chromium creep resistant steels or hardfacing. Non-ferrous and austenitic steel wires, aluminium, nickel based, stainless steel etc however, generally match closely the parent metal composition and obtaining ingots for drawing into wire is less of a problem.
MIG/MAG welding solid wires are provided in diameters ranging from 0.6 to 2.4mm, the most commonly used diameters being 1.2 and 1.6mm.
As mentioned above, the solid wires are generally formulated to match the composition of the alloy to be welded. Silicon, 0.5 to 0.9%, and perhaps aluminium, up to 0.15%, are added to ferritic steel wires to provide de-oxidation; carbon content is generally below 0.1%.
Alloying elements such as manganese, chromium, nickel and molybdenum are added to the ingot to provide improved mechanical properties and corrosion resistance. In addition the carbon and low alloy steel wires are often copper coated, both to reduce corrosion during storage and to improve welding current pick-up in the contact tip.
The stainless steel and non-ferrous wires are not copper coated. Poor control during the drawing operation may form laps on the wire surface that trap contaminants and give rise to porosity, as can a poor quality copper coat on ferritic steel wires.
Porosity from drawing defects can be a particular problem with aluminium alloy wires and where high quality weld metal is required, then shaving the wire to remove defects on the wire surface is recommended.
The cored wires are small diameter tubes in which are packed fluxes and alloying elements. There are two fundamental types, one containing mostly fluxes, the other containing metal powders. There is a sub-class of the flux cored wires, the self-shielded wires, that contain gas-generating compounds that decompose in the arc to provide enough shielding gas so that additional gas shielding is not required.
In cross-section, the wires may be seamless tubes packed with the flux and extruded before being drawn into a wire. Alternatively, they may be or made by rolling a flat strip into a 'U', filling this with the flux or metal power and then folding this into a tube. The edges of the tube may be butted together or overlapped.
The seamless and closed butt wires tend to have thicker walls and therefore less fill than the overlapped wires, perhaps as little as 20% of cross sectional area compared with 50% for the overlapped wires. This enables the overlapped wires to contain more alloying elements and they are therefore often used for stainless steel and hardfacing welding.
Cored wires have a number of advantages over the solid wires. The reduced current carrying cross-sectional area of the wire results in greater current density and an increase in burn-off rate with increased deposition.
The flux also produces a slag that will control weld bead shape enabling higher welding currents to be used in positional welding than can be used with MAG. A 7mm throat fillet is possible in the horizontal-vertical position, for example. The slag will also react with the weldpool and provide better properties than can be achieved with MAG. Good Charpy impact properties down to -50°C are achievable in carbon steels with the correct wire.
Disadvantages with the cored wires are:
* The wire is mechanically weak and over-pressure on the wire drive
rolls may crush the wire preventing it from feeding through the contact tip.
* The flux cored wires produce a slag that must be removed.
While solid wires often produce islands of a glassy slag that tend to lie in the finish craters this does not necessarily prevent a multi-pass weld being made without de-slagging.
This is not possible with flux cored wires, restricting their use in applications such as robotic welding to single pass welds. Metal cored wires are less of a problem in this context and are often used in fully automated, multi-pass applications.
As with MMA electrodes, the flux in the core may be either rutile or basic, the rutile flux providing a smooth arc, easy slag removal and 'welder appeal', the basic fluxes providing better mechanical properties and cleaner radiographic quality welds.
Hydrogen control is less of a problem than with MMA electrodes. Both rutile, basic and metal cored wires all have very low hydrogen potential levels, allowing lower preheat than might otherwise be the case and enabling rutile wires to be used in applications such as the welding of high strength or thick section steels. Hydrogen pick-up on the shop floor is also less of a problem as the flux/metal powder is contained within a sealed tube, preventing moisture ingress. Seamless wires tend to be better in this respect than seamed wires.
There are a number of specifications detailing the requirements for solid and cored wires for MIG/MAG, FCA and MCA welding and these will be covered in the next article.
This article was written by Gene Mathers.

Part 5

Welding consumables Part 5 - MIG/MAG and cored carbon steel wires Part 1 Part 2 Part 3 Part 4 To ensure that there is a consistency in composition and properties between wires from a variety of manufacturers, specifications have been produced that enable a wire to be easily and uniquely identified by assigning the consumable a 'classification', a unique identification that is universally recognised.
The two schemes that are dealt with in this article are the EN/ISO method and the AWS scheme. There are such a large number of specifications covering the whole range of ferrous and non-ferrous filler metals, both solid wire and cored, that it will not be possible to describe all of these here. This article therefore reviews just the carbon steel specifications.
The identification of the solid wires is relatively simple, as the chemical composition is the major variable although both the EN/ISO and the AWS specifications detail the strength that may be expected from an all-weld deposit carried out using parameters given in the specification. It should be remembered, however, that most welds will contain some parent metal and that the welding parameters to be used in production may be different from those used in the test. The result is that the mechanical properties of a weld can be significantly different from those quoted by the wire supplier, hence the need to always perform a procedure qualification test when strength is important. In addition, the mechanical properties specified in the full designation include the yield strength. (In the EN/ISO specifications, the classification may indicate either yield or ultimate tensile strength).
When selecting a wire remember that the yield and ultimate tensile strengths are very close together in weld metal but can be widely separated in parent metal. A filler metal that is selected because its yield strength matches that of the parent metal may not, therefore, match the parent metal on ultimate tensile strength. This may cause the cross joint tensile specimens to fail during procedure qualification testing or perhaps in service.
The EN/ISO specification for non-alloyed steel solid wires is BS EN ISO 14341. This specification classifies wire electrodes in the as-welded condition and in the post weld heat-treated condition, based on classification system, strength, Charpy-V impact strength, shielding gas and composition. The classification utilises two systems based either on the yield strength (System A) or the tensile strength (System B):
* System A - based on the yield strength and average impact energy of
47J of all-weld metal.
* System B - based on the tensile strength and the average impact
energy of 27J of all-weld metal.
In most cases, a given commercial product can be classified to both systems. Then either or both classification designations can be used for the product.
The symbolisation for mechanical properties is summarised in Table 1A for classification system A and Table 1B for classification system B.
For classification system B, the "X" can be either "A" or "P", where "A" indicates testing in the as-welded condition and "P" indicates testing in the post weld heat-treated condition. The symbol for chemical composition is summarised in Table 3A and 3B of BS EN ISO
14341 based on each classification system. For classification system A, the standard lists eleven compositions, too many to describe completely here. Six of the wires are carbon steel with varying amounts of deoxidants, two wires contain approximately 1% or 2.5% nickel and an additional two wires contain around 0.5% molybdenum. The designation of these wires is for example G3Si1, 'G' identifying it as a solid wire, '3' as containing some 1.5% manganese and Si1 as containing around 0.8% silicon; G3Ni1 is a wire with approximately 1.5% manganese and 1% nickel.
Table 1A Symbols for mechanical properties based on classification system A
Symbol Min Yield Strength
N/mm 2 UTS

N/mm 2 Min Elongation
% Symbol Charpy-V Test 47 J at Temp °C
35 355 440 to 570 22 Z No requirements
38 380 470 to 600 20 A +20
42 420 500 to 640 20 0 0
46 460 530 to 680 20 2 -20
50 500 560 to 720 18 3 -30
4 -40
5 -50
6 -60
7 -70
8 -80
9 -90
10 -100
Table 1B Symbols for mechanical properties based on classification system B
Symbol Min Yield Strength
N/mm 2 UTS

N/mm 2 Min Elongation
% Symbol Charpy-V Test 27 J at Temp °C
43X 330 430 to 600 20 Z No requirements
49X 390 490 to 670 18 Y +20
55x 460 550 to 740 17 0 0
57x 490 570 to 770 17 2 -20
3 -30
4 -40
5 -50
6 -60
7 -70
8 -80
9 -90
10 -100
A full designation could therefore be ISO 14341-A-G 46 5 M G3Si1 where the '-A' designates the classification system A, the "-G" designates solid wire electrode/or deposits, and the 'M' designates a mixed gas.
An example of a System B designation could be ISO 14341-B-G 49A 6 M G3, where "A" indicates testing in the as-welded condition.
A full designation could therefore be BS EN 440 G46 3 M G3Si1 where the 'M' designates a mixed gas and 'C' 100% CO 2.
The AWS specification AWS A5.18 covers both solid, composite stranded and cored wires comprising six carbon steel filler metals for MAG, TIG and plasma welding in both US and metric units.
The classification commences with the letters 'E' or 'ER'. 'E'
designates an electrode. 'ER' indicates that the filler metal may be used either as an electrode or a rod. The next two digits designates the tensile strength in either 1000s of psi.(ksi) or N/mm2 eg ER70 (70ksi UTS) or ER48 (480N/mm 2 UTS). However, note that there is only one strength level in the specification.
The next two characters identify the composition, essentially small variations in carbon, manganese and silicon contents, the wire type (solid wire (S) or metal cored or composite wire (C)) and the Charpy-V impact values.
With one exception, the solid wires are tested using 100% CO2, the cored wires with argon/CO2 or as agreed between customer and supplier, in which case there is a final letter 'C' designating CO2 or 'M', a mixed gas.
The permutations in these identifiers are too many and too complicated to be able to describe them all in sufficient detail but as an illustration, a typical designation would be ER70S-3, a 70ksi filler metal, CO2 gas shielded and with minimum Charpy-V energy of 27J at -20°C. E70C-3M identifies the wire as a solid wire 70ksi UTS metal cored filler metal, 27J at -20°C and tested with an argon/CO2 shielding gas.
The EN/ISO specification for non-alloy steel flux and metal cored wires is BS EN ISO 17632. This covers gas shielded as well as self-shielded wires. The standard identifies electrode based on two systems in a similar way as BS EN ISO 14341, indicating the tensile properties and the impact properties of the all-weld metal obtained with a given electrode. Although the specification claims that the wires are all non-alloy, they can contain molybdenum up to 0.6% and/or nickel up to 3.85%. The classification commences with the letter 'T', identifying the consumable as a cored wire.
The classification uses the same symbols for mechanical properties as shown in Table 1A&B and a somewhat similar method to describe the composition as BS EN ISO 14341. Thus MnMo contains approximately 1.7% manganese and 0.5% molybdenum; 1.5Ni contains 1% manganese and 1.5% nickel. In addition to the symbols for properties and composition, there are symbols for electrode core composition. Table 2 summarises the symbols for electrode core type and welding position in accordance with classification system A. Classification system B uses Usability Indicators as oppose to a one-letter symbol for electrode core type, which can be found in Table 5B of BS EN ISO 17632.
Table 2 Symbols for electrode core type and position based on classification system A
Flux Core Welding Position
Symbol Flux Core Type Shielding Gas Symbol Welding position
R Rutile, slow freezing slag Required 1 All
P Rutile, fast freezing slag Required 2 All except V-down
B Basic Required 3 Flat butt, flat and HV fillet
M Metal powder Required 4 Flat butt and fillet
V Rutile or basic/fluoride Not required 5 V-down and (3)
W Basic/fluoride, slow freezing slag Not required
Y Basic/fluoride, fast freezing slag Not required
Z Other types
In addition, there are symbols for gas type. These are 'M' for mixed gases, 'C' for 100% CO2 and 'N' for self-shielded wires and 'H' for hydrogen controlled wires. A full designation may therefore be ISO 17632-A -T46 3 1Ni B M 1 H5 in accordance with classification system A. For classification system B, an example may be ISO 17632-B -T55 4 T5-1MA-N2-UH5, where "T5" is the usability designator, "A" indicates test in the as-welded condition, "N2" is the chemical composition symbol, and "U" is an optional designator.
The American Welding Society classification scheme for carbon steel flux cored wires is detailed in the specification AWS A5.20. The full designation is ten characters in length beginning 'E' for an electrode then designators for strength, welding position, cored wire, usability, shielding gas, toughness, heat input limits and diffusible hydrogen, the last four designators being optional.
There are two strength levels - E7 (70ksi UTS) and E6 (60ksi UTS) followed by a designator for welding position,'0' for flat and horizontal and '1' for all positions, including vertical-up and vertical-down.
The next symbol 'T' identifies the wire as being flux cored and this is followed by either a number between 1 and 14 or the letter 'G' that identifies the usability. This number refers to the recommended polarity, requirements for external shielding, and whether the wire can be used to deposit single or multi-pass welds. 'G' means that the operating characteristics are not specified. The sixth letter identifies the shielding gas used for the classification, 'C' being 100% CO2, 'M' for argon/CO2, no letter indicating a self-shielded wire.
The non-compulsory part of the designation may include the letter 'J', confirming that the all-weld metal test can give Charpy-V values of 27J at -40°C; the next designator may be either 'D' or 'Q'. These indicate that the weld metal will achieve supplementary mechanical properties at various heat inputs and cooling rates. The final two designators identify the hydrogen potential of the wire.
A full AWS A5.20 designation could therefore be E71T-2M-JQH5. This identifies the wire as a cored, all positional wire to be used with
argon/CO2 shielding gas on electrode positive polarity. The weld metal should achieve 70ksi tensile strength, 27J at -40°C, 58 to 80ksi yield strength at high heat input, a maximum 90ksi at low heat input, and a diffusible hydrogen content of less than 5ml of H 2 /100g of deposited weld metal.
This article was written by Gene Mathers, reviewed and modified by Runlin Zhou.


On 3/3/11, manpreet <manpreetsin88@rediffmail.com> wrote:
> Hi Shri,There are&nbsp;some importent&nbsp;information missing like
> grade of material and thickness, E7018 electrode contains iron powder
> in the flux,With the root run a fast cooling electrode is desirable
> (that is why cellulosic electrodes are so commonly used)and the E7018
> is not a fast cooling electrode.I would suggest to go for E7010 for
> root runs which can be used for higher API grades, having said that
> you should also know that E7010 may induce hydrogen into the weld and
> cause cold cracking if Preheat not done. also E6010 is widely used for
> Pipe root runs.RegardsManpreet Singh
> 2011/3/2 Engineer Mech &lt;mengineer010@gmail.com&gt;&gt;
> Hi All,&gt;&gt;Can I use E 7018 in Pipe root runs? Wats the
> disadvantages?&gt;Can i go E 7018 root run&amp; filler WPS
> qualification?&gt;&gt;Regards&gt;Srinivasan&gt;&gt;--&gt;To post to
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[MW:34820] RE: 34813] Clarification in Rate of heating and cooling.

Hello,   Please see the response below.   Regards.   P. Goswami, P. Eng, IWE.   From: materials-welding@googlegroups.com <materials-weld...