How To Prep Aluminum For Welding

How To Prep Aluminum For Welding - When asked recently by a local welding supply specialist what was the most important thing for a successful aluminum welding job, he replied that it was clean, clean and clean.

Welding aluminum presents its own set of challenges.

Welding with filler and base metals can cause excessive difficulty and lead to poor quality welds.

How To Prep Aluminum For Welding

Aluminum's natural oxidation is also something you need to consider. It is crucial to prepare properly before welding, especially if fabrications must meet the requirements of industry codes like AWS D1.2 which governs structural welding of aluminum.

You can follow certain steps when treating and preparing filler and base metals.

This will ensure that you are not exposed to dirt, grease, and other airborne contaminants.

It also helps to prevent the aluminum from oxidizing naturally.

These steps will be covered and we'll give you best practices so that you don't sabotage your aluminum welding process before you even start.


Aluminum's Natural Challenges

Steel presents more immediate problems than aluminum.

Aluminum is more susceptible to problems than steel, including lack of fusion from the tough oxide layer and lack of penetration by high thermal conductivity.

Also, aluminum can be porosity because of the high solubility hydrogen in molten aluminum.

Therefore, it is important to eliminate all moisture and hydrocarbons.

Also, the thickness of the oxide layer must be controlled so that it does not hydrate due to excessive moisture.


Proper storage and handling of aluminum filler and base metals

The weld puddle can become porous by introducing oxidides of aluminum TIG filler metal into it.

MIG filler metals containing oxydes can cause a variety of problems including an erratic, increased resistance and poor feeding.

Thicker oxide layers on aluminum base materials must be removed mechanically to avoid contaminating the weld.

These are some things you can do to prevent this from happening in storage:

To minimize condensation, store all welding filler metals or base metals in dry areas with minimal temperature fluctuations.

You should keep welding filler metals in a dry, heated area or cabinet.

To prevent water contamination and condensation between layers, store aluminum pieces vertically.

To minimize condensation, make sure that all base and filler metals are brought into the welding area at least 24 hours before welding.

Before welding, keep filler metals protected.

These would include a TIG rod case and MIG wire spool cover.


The Best Joint Preparation to Weld Aluminum

Preparing the joint for welding involves two steps: mechanically removing any oxide layer (which has a higher melting temperature than the base metal), and removing any oil or grease that could cause a contamination.

Avoid using cutting methods that leave a smeared or ground surface.

A high-speed circular saw can be used to cut aluminum, while a band-sawed surface may cause smearing.

Grinders should not be used if possible.

However, a coarse disc grinder can be preferred to a wheel grinder if that is your only choice.

It is important to use a fast, sharp method that cuts through the material quickly and not smearing it.

For example, a wheel grinder can embed stones into aluminum, which could lead to a contamination or inclusion.

Smeared surfaces can cause lack of fusion. Prior to welding, it is important to file the surface.

Use oxyfuel flames for heating, oxyfuel gas cutting, carbon-arc cutting, gouging, or carbon arc cutting to avoid heat damage.

These processes can damage heat-sensitive areas and encourage the growth and hydration oxide films on the surface.

Plasma arc cutting and laser cutting are better than gouging and plasma arc cutting because they are less likely to introduce hydrogen or moisture to the oxide layer.

Remove the plasma arcs and laser edges from 2xxx and 6xxx series alloys mechanically.

These alloys' melted edges can cause heat-affected zone conditions and solidification cracks.

Cut off a minimum 1/8 inch of metal at the edge.

To remove and cut metal chips, use mechanical methods such as a milling machine or a coarse burr grinder.

Avoid aluminum cutting applications using lubricants whenever possible.

Hydrocarbons in petroleum-based lubricants can cause cracking and porosity by introducing hydrogen into the joint.

The majority of aluminum that comes from the factory will have oil and grease.

First, clean the surface with a solvent. Next, use a cheesecloth (or paper towel) to dry the joint.

These are preferable because they absorb more oils/moisture and are porous.

Make sure to clean the other side of the joint as well, so no impurities get through the aluminum or into the weld pool.

Use a solvent that does not leave behind any residue.

Avoid using chlorinated solvents near the welding area as these chemicals can cause toxic gas formation in the presence of the welding arc.

Use shop rags for cleaning welding joints.

These rags can transfer oil and dirt onto the welding surface.

To blow off the joint, do not use compressed air.

Compressed air can contain oil and moisture contaminants.

Only clean the joint with a stainless steel wire brush after solvent cleaning.

The metal surface is contaminated by hydrocarbons and other contaminants that are embedded in wire brushing.

This makes the brush ineligible for cleaning.

To clean any etched metal, use a stainless-steel wire brush.

Before welding, it is important to remove any by-products of etching.

To prevent contamination of the weld joint, clean all wire brushes and cutting instruments frequently.

If possible, use dedicated brushes for welding aluminum.

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