Storage and handling of welding consumables

Storage and handling of welding consumables

consist of the following parts:

•฀ Hydrogen induced cracking

•฀ Coated electrodes

•฀ Flux Cored Wires

•฀ Submerged arc welding fluxes

of moisture in the coating, even after the final drying operation during manufacture. This moisture

decomposes in the arc during welding to give

hydrogen, (H), and consequential risk for hydrogen

induced cracking.

The moisture is bound in the crystalline structure

of some of the minerals in the coating and requires

a relatively high temperature to remove it. Basiccoated electrodes are designed to be dried at high

temperatures, resulting in a low coating moisture

level, and are often referred to as “low hydrogen


Hydrogen induced cracking

Hydrogen in welded joints in ferritic materials can

give rise to hydrogen induced cracking, also known

as cold cracking and delayed cracking

The major factors which influence the risk of this

type of cracking are chemical composition of the

steel (Carbon Equivalent factor CE), cooling rate

and hydrogen content of the weld metal.

The most common sources of hydrogen are:

•฀ Moisture in electrode coatings or SAW flux

•฀ Drawing lubricants on cored wires

•฀ Moisture in the atmosphere or shielding gas

•฀ Condensation, rust, oil, paint or primer in the

weld joint area

Coated electrodes can be divided into:

1) Non-alloy C-Mn, rutile or acid-rutile coated

electrodes , with H>15 ml/100g weld metal.

2) Non-alloy C-Mn and low alloy, basic-coated

electrodes, with H<10 or <5 ml/100g weld metal.

3) High alloy austenitic stainless steel electrodes,

rutile or basic coated, where hydrogen diffusion

does not occur because hydrogen is soluble in

the austenitic atomic structure, even at room


Moisture, lubricant etc. decomposes in the arc

during welding to give hydrogen,(H), which is

readily dissolved in the weld pool. On cooling this

(H) tries to escape via diffusion because it is less

soluble in the solid weld metal compared to the

molten weld pool. Any (H) that remains trapped

in the joint can cause hydrogen induced cracking.

Cracks generally form in the coarse-grained, HAZ

of the base material but for very high strength weld

metals cracks can also arise in the weld metal itself.

By following the recommended storage and handling procedures for welding consumables, moisture

levels can be minimised, along with the associated

hydrogen induced cracking risk.

Of the above listed groups, it is only types 1 and 2

which can give rise to hydrogen induced cracking.

For steel grades with a yield strength > 355MPa

the use of type 2 electrodes is recommended.

Type 3 electrodes are also dried at high temperature,

but this is to minimise the risk of porosity, also

caused by moisture in the coating.

Unfortunately, electrode coatings are hygroscopic,

i.e. they pick up moisture from the surrounding

atmosphere if freely exposed to it. Suitable coating

formulation design can minimise this effect but not

eliminate it. For this reason it is necessary to ensure

that electrodes are not able to absorb moisture (by

correct choice of packaging, storage and handling)

or, alternatively, to re-dry them before use.

Storage and handling of coated electrodes

Coated electrodes always contain a certain amount