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Welding of non alloyed steel

Oerlikon solutions for non alloyed steels welding and cutting applications

Unalloyed steels are in fact alloys of iron and carbon (proportion of 0.12% to 2.0%). The carbon steels are very widely used in large number industrial activities as transportation : automobile, trucks, railway cars and naval construction – pipe work and boiler making for chemical industries – offshore constructions – wind tower - building – mining… ).

Oxy flame and plasma cutting of non alloyed steel

Oxy flame and plasma cutting are the processes  that can be used for thermal cutting of unalloyed steels as well in manual applications with the range of CITOCUT machines and in automatic applications on automatic cutting table (OPTITOME – ALPHATOME – OXYTOME and PLASMATOME) with MACH HP for oxy-fuel cutting and NERTAJET HP for plasma cutting.

MMA equipment for non alloyed steel welding

The equipment is composed of a power source providing the welding current (from 10 A to ~500 A) by transformation of the primary main electrical network current (single phase or three phase 230 V to 440V). Modern arc power sources use "Inverter" technology providing cost effective solutions combined with increased ease of use (good striking, very stable welding current…).
The inverter power sources are also lighter than transformers for same welding current improving portability.

In Oerlikon range the equipment for MMA welding are named CITOARC. In addition a MMA welding kit is necessary to connect the power to the piece to be welded and to the electrode holder maintaining the covered electrode.

Consumables for MMA welding of unalloyed steel

The core metal composition of the electrode is generally similar to the base material while 2 main different coatings are possible rutile or basic (also named low hydrogen).

  • Rutile coated electrode are used for current works. Ease of use and good appearance of the weld joint are the main features but with limited mechanical properties.

In the Oerlikon range the designations are OVERCORD - FINCORD and CITOCORD with slight difference regarding welding positions.
Cellulosic coated electrodes FLEXAL are also available they are dedicated to pipe welding in position.
FERROMATIC electrodes with addition in the coating of iron powder provides high recovery welds (up to 200 %)

  • Basic coated electrodes create welds with less hydrogen content providing higher mechanical resistance for high security works. Handling of these electrodes is more delicate and require more dexterity from the welder.

In the Oerlikon range the designation are SUPERCITO – TENAX and SPEZIAL. A specific care has to be taken with basic electrode because the hygroscopic feature of the coating. Electrodes must be kept in dry conditions or baked before use, Oerlikon with the specific packaging solution named DRYPACK avoid to redry the electrodes after the opening of the packaging.

SPEZIAL is a double coated basic electrodes developed by Oerlikon. Advantages of the double coating with the SPEZIAL are numerous :
  • A fusion close to the one of rutile coated electrode with welding quality equivalent to basic electrode quality (very high tenacity).
  • Not sensitive to magnetic blow-out effects (straight crater, not flared).
  • Easy striking and restriking.
  • Great flexibility of use in all positions, even very difficult ones (very closed chamfers, poor accessibility, irregular spacing and preparations of the edges to weld).
  • Glossy vitrified black slag self-removing
  • Very sound welds from striking (no porosities or blow holes) with no undercuts or spatters.
  • SPEZIAL is versatile and  may be used with all welding currents
    - direct current (+ polarity at the electrode) power sources, rectifiers and inverters.
    - alternating current power sources (transformers supplying no-load voltage >65 V).

TIG equipment & consumables for non alloyed steel welding

The equipment is composed of a power source providing a DC welding current (from 10 A to ~500 A ) by transformation of the primary main electrical network current (single phase or three phase 230 V to 440V). Modern TIG power sources use "Inverter" technology providing cost effective solutions combined with increased ease of use (good striking, very stable welding current…).
The inverter power sources are also lighter (up to 10 times) than transformers for same welding current improving portability.

In Oerlikon range the equipment for TIG DC welding are named CITOTIG DC. In addition a TIG welding torch with a non-consumable electrode in Tungsten is required. Argon gas cylinder and a regulator-flowmeter is necessary to control the flow of the argon (Ar) shielding gas.

The choice of the filler metal will be done in accordance with base material to be weld. The Oerlikon range covers most of the current applications. CARBOROD is the commercial designation of this rods.

Plasma arc welding of unalloyed steel

Plasma arc welding is similar to TIG welding with a key difference: in the welding torch the arc is mechanically constricted creating together with the plasma gas an ionized atmosphere of high temperature. At the impact point of the plasma base material is melted with a great energy concentration achieving a deep and narrow penetration. The plasma arc and the pool are protected by a shielding gas added from the torch.


Plasma arc welding process can be used manually for low welding intensity (~15 A - micro-plasma) but is more often employed in automatic applications for high quality works in piping and in boiler making.
Filler metal is not mandatory especially for root pass but will improve productivity for large welds.

MIG-MAG equipment for non alloyed steel welding

MIG/MAG welding equipment is composed of a power source providing the welding current, a wire feeder (built-in or separate), a welding torch or gun and a device for shielding gas supply.
Various technologies for the electrical power source are available step control transformers (CITOLINE and CITOMIG) or inverters with digital control (CITOSTEEL, CITOPULS and CITOWAVE). Modern MIG-MAG power sources use digital controlled inverter technology providing cost effective solutions combined with increased ease of use (lower weight, very stable welding current…).

With these power sources, the current metal transfer modes (globular, short-circuit, spray and pulsed spray) are available but several evolution developed and patented by Air Liquide Welding are possible for example:

  • Speed Short Arc (SSA) increases the welding speed, reduces sheet deformation, allows work in position and improves the overall quality of the welds
     
  • High Penetration Speed (HPS) that improves by 50% the productivity of MIG/MAG operations by : reduction of number of passes compared to a classic Spray Arc transfer – possibility of welding in restricted joints with tight angles with long stick-out – reduction of sheet distortion and heat affected zone

Consumables for MIG-MAG welding of unalloyed steel

Welding consumables. CARBOFIL, CARBOFIL 1 and CARBOFIL 1A are the commercial designations of the solid wire for welding unalloyed steels in the Oerlikon range. Wire diameters are comprised between 0.6 mm and 1.6 mm. Wire is delivered in spools for most of the manual applications and in large bulk (drums) for automatic and robotic applications .The choice of the filler metal will be done in accordance with base material to be weld.

 

CARBOFIL GOLD are solid wires with specific coating providing excellent arc stability, low level of spatters, excellent feeding properties, low consumption of contact tips.


CARBOFIL GOLD is the perfect solution for the industrial sectors of automotive and transport, manufacturing, pipe welding, steel buildings and structural steel works where are required highly reliable welding consumables for use without compromise during welding.

Flux-Cored Arc (FCA) welding of unalloyed steel

FCAW is a variant of MIG/MAG process where the wire electrode is replaced by a tubular wire containing a flux.
Main advantages are all position welding, higher deposition rate and higher versatility. Main drawback is the higher level of welding fumes.
Flux-cored wires are used in various industrial sectors: automotive and transport, manufacturing, pipe welding, steel buildings and structural steel works.

Equipment to weld with flux cored wires is the same that the one for MIG/MAG welding.
Filler material is flux cored wire and in the Oerlikon range the commercial designation of these wires is CITOFLUX or FLUXOFIL according to the technology folded or tubular.

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Submerged Arc Welding equipment & consumables for non alloyed steel

The Submerged Arc Welding (SAW) equipment is consisting in :

  • one (or several) electrical power source providing high intensity welding current in DC (or AC),
  • a welding head feeding the flux and the electrode wire to the joint,
  • a flux feeding system storing the flux and controlling the flux deposition

 

Filler material is a combination of :

  • a flux (fused or bonded) : a mix of fluorides of calcium and oxides of aluminium, titan, manganese, magnesium or silicon. It comes with  a specific granulation size.
    In the Oerlikon range the commercial name is generally OP and most of the Oerlikon fluxes is suitable for welding of unalloyed steels.
  • a solid wire that in the Oerlikon range is designated OE or a flux cored wire named FLUXOCORD.

Most used combinations for welding unalloyed steels are :
- With solid wire : OE S1, OE S2, OE S4 or OE SD3/OP 191, OP 160
- With flux cored wire : FLUXOCORD 31 or 31HD/OP 121TT

More about the MMA welding process

MMA welding (Manual Metal Arc) or as per AWS SMAW (Shielded Metal Welding) use a consumable steel electrode covered with a flux.

An electric arc is generated between the plate to be joined and the stick electrode. With the heat generated in the arc, both (the piece and the electrode) are melting thus creating the weld pool. The coating of the electrode also melts and forms a shielding gas preventing the melted pool. As the welding operation is going on, the melted coating provides a slag that has to be removed. This process is one of the oldest methods of joining. Big drawbacks regarding this process are to be mentioned: it produces sparks and fumes, post-weld cleaning is important, it is a quite slow process and it requires a high level of skill from the welder. Low cost, flexibility portability and versatility are the main advantages of the process.

More about the TIG welding process

TIG welding (Tungsten Inert Gas) or as per AWS GTAW (Gas Tungsten Arc Welding)

In this process an arc is generated between the base material and a non meltable tungsten electrode part of the welding torch. At the point of contact of the arc the base material is melted and an additional filler material is provided into the pool. The pool is protected by a shielding gas (generally argon because tungsten is sensitive to oxygen) provided from the torch.

Advantages of the process are:  the clean and high quality of the welds with high penetration, requiring little or no further works for post-welding clean. The main drawback is that TIG is the slower process in arc welding.
The process can easily be used in automation application.

More about the MIG-MAG welding process

MIG-MAG welding (Metal Inert Gas or Metal Active gas) or as per AWS GMAW (Gas Metal Arc Welding)

In MIG-MAG process an arc is generated between the base material and a continuous wire electrode that is consumed. The filler metal is the electrode wire fed throughout the torch.
Shielding gas is necessary to protect the arc and the molten pool. Various possibilities can be used: inert gas (a mixture of Argon + CO2) for MIG welding and CO2 for MAG welding. The shielding gas choice depends on various factors and on the required results.


MIG/MAG welding process is the most used method in all industrial applications as it is the fastest, economical and a high productivity process, requiring low skills from the welder. Disadvantages of the process were poor quality of weld appearance and spatters but modern power sources with advanced arc transfer modes provide much better results that in the past.
MIG/MAG process is used in manual applications but is more and more often used in automatic and robotic applications.

More about the Submerged Arc Welding process

Submerged Arc Welding (SAW) is an arc welding process where an arc is generated between the base material and continuous wire electrode (solid or flux cored wires).

The arc and the molten pool are completely covered by a layer of flux, thus no sparks, no radiation and no fumes are produced. The SAW process is almost always operated in automatic application, flat butt or fillet positions for long welding beads or high thickness. Welding current is high (up to 1200 A in single wire and much more when used in multi-wire) and the deposition rate is very high. It is the arc welding process with the highest productivity.


Main advantages are very sound welds, productivity and important thickness weldable in one pass, no fumes and non-visible arc radiation. Main drawback is the heavy automatic equipment necessary to operate the process.
Submerged Arc Welding process is used in various industrial sectors: transportation industries (trucks and railway coaches..) pipe fabrication and heavy structural steel works.