Welding Problems And How To Fix Them

There are many causes of welding problems. Bad welds are not good. A weld is supposed to fuse two metal parts together by using a similar metal as a filler material, a poor weld is not only unsightly but is also unsafe, especially in construction where peoples lives may depend on it. Here we outline some welding defects and how to remedy them.

Causes of Weld Splatter

 Check the welding current to ensure its not to excessive. Check the size of the welding electrode for the job, an electrode to small and a high current will cause weld splatter.

Use a short weld arc with the appropriate current for the job. Use an anti splatter spray product, these products prevent weld splatter from adhering to welding equipment and metal surfaces including aluminium and other alloys.

Anti-spatter water based spray that prevents weld spatter from adhering to metal surfaces and welding components, available in a range of sizes.

 

Cause Of Weld Distortion

Distortion of the parent weld metal can be due to several factors, genrely speaking it is a result of the deposited weld shrinking.

Welding problems of distortion can be eased by clamping the job first then tack welding at various intervals,  before completing the full weld. Also using a peening hammer or powered tool while the weld is hot will assist in nullifying the shrinkage.Try to Develop a weld sequence to prevent  localised over heating.

On larger projects using heavy steel, pre heating can also help in reducing weld distortion.

How To Prevent The Warping When Welding Sheet Metal.

Choose welding electrodes that offer a high weld speed and moderate penetration, this will assist in giving less shrinkage to the weld area.

Avoid Excessive heat. This can be avoided by welding quickly.

Joint preparation. The better you prepare the join the less heat you will pump into the job, try to avoid a wide root opening. Hammering the edges of the join at the root will elongate the edges which when welded will shrink back to the original shape they were in, helping to prevent sheet metal warping.

During the welding procedure, try to make welds in minimal passes as possible, clamp joints where possible ad, if possible back up the weld so as to cool the joint as soon as possible.

Welding Distortion

Reasons for Poor weld Appearances

Poor welds not only look bad but also are likely to be weak. Use the following as a guide to make good clean neat welds.

Make sure the welding current is correct for the thickness of metal being welded, and for the type of material being welded, do not use excessive welder current. Use the correct technique and hand peice manipulation, eg vertical down, vertical up ect. Make smooth passes and travel rates.

Choice of electrodes, weld in the position recommended for the particular electrode being used, ensuring the weld rod is the right one for the job.

Prepare all joins correctly, trying to weld a but weld without preparation is asking for trouble.

3 Common Welding Problems

Cracked Welds and How To Avoid Them

Joint preparation should have a good root gap. Don’t make the weld in string beads. Lay down weld metal full size in short sections from 8.0 to 10.0 inches.. (Commonly called a block sequence.)

 Check for excessive rigidity of joint.

Redesign the structure and modify the welding procedure in order to eliminate rigid joints. Step 2. Ensure the welds are not too small for the size of the material to be joined. When welding heavy sections make sure the root is sufficient, fill the joint with several smaller passes. Again use correct welding processes.

Check the welder polarity and current, keep a steady arc length,  welds should be sound with proper fusion of the base metal.

Try to leave the ends free on the weld until the last pass, allowing sufficient movement.

Welding sequence should be such as to leave ends free to move as long as possible. For larger work pre heating will also assist in reducing localized stresses.

Causes of Weld Undercut.

Avoid high speed welding and use recommended current settings on the welder. Use the right electrode for the job and sound manipulation practice. Sometimes a too large electrode will cause a oversize weld puddle that in turn can result in undercut.

When using the weave technique, avoid over weaving as this will cause undercut, a proper weave should generally be no wider than three times the electrode diameter.

When making a horizontal fillet weld, the electrode should not be to vertical as this can cause weld undercut

Reasons For Poor Penetration.

Poor weld penetration can lead to cold welds. This is when the deposited metal from the electrode fails to penetrate the plate to be welded, with the weld virtually sitting on the plate as if glued on. This is more common with Mig welding and can be a serious problem when used in structural applications.

Make sure the parent metal is sound and clean, remove any rust or contamination by grinding or other abrasive methods.

Its essential that the correct electrode is being used for what they were designed to weld.

Also the welding position should be taken into account. For thicker metals, make sure you have a proper root prepared with sufficient gap at the joint. Its a good idea to use a backup bar where possible.

Between passes, chip or back grind the weld before continuing. Should the weld require an X-ray this step is critical as there should be no slag left at the weld face prior to the next pass. Start with smaller welding rods for the root passes and finish with larger ones, the root run should blister out on the reverse side of the weld.

Keep the travel of the weld steady and not to fast, good welder current is needed to maximize penetration.

Observe puddling time to see if it is sufficient to let trapped gases to escape. A good weld puddle ensures the weld metal is molten longer and will often give a sounder weld. If the weld has a series of string beads its possible for porosity to occur, a good fix for this is to utilize a small weaving action.

Causes of Brittle Welds

Is the electrode the right one for the job?. Bare electrodes will produce brittle welds. The use of Shielded arc electrodes is required to produce ductile welds. Check the size of the electrode also.

Avoid using excessive current, welding settings need to be in line with good welding procedures.

The composition of the parent metal should be known before welding, any alloy elements present will absorb into the weld, also the use of several weld passes will assist in making welds less brittle.

When welding in narrow groove joints use an electrode small enough to properly reach the bottom of the joint. 

The deposited metal should fuse with the base metal and not curl away from it or merely adhere to it.

The causes of welding defects are numerous, however by adhering to proper welding techniques and the use of good equipment most welding problems can be overcome and not encountered in the first place.