In any welding project, achieving a strong and durable weld is important. However, there are times when the weld can be weak or even broken. This can be caused by a number of factors, such as incorrect welding techniques, bad materials, or even operator error. In this blog post, we will discuss seven signs that indicate a bad weld.
What makes a Good Weld?
To understand what goes into making a good weld, you need to understand what a weld actually is. A weld is a joint between two pieces of metal that is made through the fusion of the metals. In order to make a solid weld, the metal needs to be melted and fused together in such a way that there are no gaps between the two pieces of metal. This results in a joint that is strong and durable.
As you are probably already aware, many different types of welds can be made depending on the type of metal being welded, the strength required from the weld, and more. For example, if you are welding steel to steel, you will want to use the fillet weld. If you are making structural welds, the groove weld is ideal. You will use the complete penetration weld for welds that require a lot of strength, such as between steel and stainless steel.
Now that you know what goes into making a good weld let’s talk about five signs that indicate a bad weld.
Porosity refers to the presence of holes in the weld metal. It can take many forms:
- distributed porosity
- surface-breaking pores
- Pipes from the crater
Porosity can lead to some serious problems. Some cases of fatigue can lead to weakness and even failures due to porosity.
We Can List The Following Possible Causes of Welding Porosity:
- Surface contamination can include oil, grease, and moisture.
- Poor gas shielding is caused by oxygen absorption and Nitrogen in the weld pools.
- Surface coatings Large amounts of fumes can get trapped during welding.
The separation of the filler weld metallic or discontinuity between the base and filler metal. There are many types: transverse, longitudinal, transverse, and throat.
It can lead to some serious problems like failure and propagation of crater cracks.
Cracked weld is caused by port parts fit-up, and rapid cooling is some of the possible causes. Poor width-to-depth ratios, low melting points of tramp elements in the base, concave surfaces, or incorrect electrodes can cause most centerline and longitudinal cracks.
Welding Slag is a type of vitreous matter that can be made from stick welding or submerged arc welding. After a welded joint is completed, slag inclusions are not added to the strength and protection of metals. They are waste in the weld material and must be removed. It is important to remove them as they will hinder inspection of the weld areas, cause a poor visual appearance, and also need to be removed if a second pass or layer is needed.
Slag results when the flux is melted in or on top weld beads using the wrong electrode technique. If the flux does not float to the top of the molten steel, it is possible for small areas to be embedded in the metal. This will not affect the structural integrity and strength of the weld.
An undercut is an area of the unfilled grove in the base metal that remains after fusion. This occurs along the weld’s toe lines. This can be easily seen in the joint design. It can lead to some serious problems like failure and propagation of crater cracks.
This is clearly an issue with welding techniques. Temperatures near the edges can be too hot, especially near the edges that are thinner or free. You can also experience erratic movements, electrode error, holding an arc too long, blowing too fast, and not pausing enough on the toes.
When the weld fails to fuse with the base material, it is called a lack of fusion. Reduction in strength and failures are some of the effects of a bad weld.
Some causes of incomplete fusion include:
- Improper welding fusion.
- Failure to raise the base metal or the previously deposited weld material to its melting point during welding.
- Too slow of a travel speed can cause the welds to roll over the edges. This will trap slag in the gap between the base and the bead.
- The wrong angle of the electrode pushes the weld material over the slag.
- Stay within a reasonable speed, or set your amperage too high.
- Too long an arc allows the weld to fall off randomly.
During GAS welding, ARC welding, or other processes, molten metal (or non-metallic) material is splashed or scattered. Droplets are small to large pieces of hot material that stick to the base material or surrounding metal material. In some cases, they may fly off the workbench or other areas.
The nozzle can become clogged with spatter, which can cause damage to the weld beads. The accumulation of spatter projections within the nozzle can cause injuries to the user and can make the cords unusable.
Here are some possible causes:
- Pool too hot or too cool
- Shielding gas is being used.
- Wire feed can be too high or low.
- Welding wire spools that are poorly wound.
- Welding wire stick out.
- Poor connections to the ground clamp
- Incorrect welding wire storage.
- High humidity in a wet environment
- Weld contamination includes dirty surfaces, oil, paint, and mill scale.
When the groove is too narrow or the weld metal doesn’t reach the bottom of a joint, it can cause incomplete penetration. It’s characterized by decreased strength and failure. It is similar to incomplete fusion. Insufficient heat input, improper joint preparation, improper shielding gas mixture, and improper welding wire diameter are all major causes. The wrong travel speed can even cause it.
Why You Should Not Try To Fix It Yourself?
Sometimes, the defects or issues with a weld might seem minor to a beginner welder. However, it’s important to remember that even minor defects can lead to major problems later on.
Especially when it comes to weld strength and safety, even the smallest of defects can become major problems. Even if you think you can fix the weld blemish, it’s always best to let a professional welder look at it and repair it if necessary. Services for welding and metal fabrication available in Young, New South, Wales, Australia, can help you with repairs that have to be done by professionals.
These are some of the joint weld defects you might encounter and their causes. Once you know what causes them, it becomes much easier to fix them. If you’re a do-it-yourselfer, these tips will help you save a lot of money on repairs. These tips will help you earn more money by completing better-quality welds if you’re a professional welder.