Differences Between Good Weld & Bad Weld – Tips & Tricks

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Welding is undoubtedly getting a more popular and used profession across the globe, but the hobbyist market might have seen the most considerable expansion. Today’s welding machines are affordable and quite capable, so it is no surprise many have tried welding.

However, most beginners and hobbyist welders struggle to achieve the perfect weld at first. That’s why we compiled this detailed article to explain the characteristics of a high-quality weld and compare good weld vs bad weld.

What Are The Properties Of A High-Quality Welds?

Good weld quality is determined prior to the welding process, and in industry, it is usually selected by the welding fabrication drawing or blueprint. The welding fabrication blueprint provides welding symbols that strictly determine weld sizes and other dimensional requirements such as length and location.

However, some common characteristics identify the perfect welds: even metal distribution, lack of slag, no welding discontinuities, and tight and leakproof weld with high tensile strength. As a result, welds should have a consistent, smooth, and uniform appearance. In addition, a good weld will have a color-free appearance that indicates no oxidation has occurred.

MIG welding process and MIG Welds

Gas metal arc welding is one of the most straightforward processes to master, meaning you can achieve good MIG weld with little to no effort. This process utilizes a welding gun that feeds a wire electrode that acts as the filler material to join two metal pieces.

Ease of use has made MIG welding a go-to welding process in your everyday home repairs and DIY projects, but many beginners struggle to make a good weld.

A good MIG weld is easy to distinguish. The weld is straight and uniform with no slag, cracking, or holes. There are no breaks in the weld, it isn’t too thin and there are no dips or craters in the bead.

Image of a good staked MIG wled

Unlike a TIG weld, a MIG weld has no specific pattern as it is as smooth as possible. On the contrary, poor welds have holes, show a lack of strength, and don’t seem uniform. Let’s take a look at a visual representation of good and bad welds.

Keep in mind that the flux shielded arc welding process is quite similar to MIG welding, so the defects and poor and good welds result from similar mistakes. However, since the flux protects the electrode wire, there is no fear of porosity caused by a lack of shielding gas. However, flux core welding processes is somewhat hotter, so tackling thin materials might commonly result in a burn-through.

Good MIG weld and Bad MIG Weld

To achieve good metal inert gas welding results, you will need to be aware of the wire feed speed, voltage, shielding gas, and travel speed. Manufacturers usually recommend each of these factors for different material thicknesses, but if you get any of them wrong, you might deal with poor welds.

Here are visual representations that show how wire feed speed, voltage, travel speed, or lack of shielding gas affect the appearance of the weld.

Good and uniformed MIG welds that pass visual testing:

Horizontal 2F position with 2 welding beats stack together MIG welding with CO2 or MIX gas.
Horizontal 2F position with 2 welding beats stack together MIG welding with CO2 or MIX gas.
Vertical 3F Weld with MIG welding. uniformed zig-zazg beat by an experienced welder
Vertical 3F Weld with MIG welding. uniformed zig-zazg beat by an experienced welder
Single Pass with MIG welding machine on Horizontal 2F position. Spalted doe to not cleaning the material pre-weld.
Single Pass with MIG welding machine on Horizontal 2F position. Spalted doe to not cleaning the material pre-weld.

MIG welding mistakes and in general bad welding beats:

too high and too low amperage of a MIG weld
Left: amperage too high; Right: amperage too low.
too low and too high voltage of a MIG weld
Left: voltage too high, Right: voltage too low.
fast and slow travel speed of MIG weld
Left: travel speed fast; Right: travel speed slow.

Stick Welding and Stick Welds

Shielded metal arc welding is one of the most economical welding processes and is widely used for home and on-field repairs.

This welding technique is versatile enough to work with a range of materials, including alloy steel, carbon steel, stainless steel, iron, nickel, copper, and even aluminum.

A good stick weld is easy to notice, as it is straight and uniform. The thickness doesn’t change drastically and there is no spatter. In addition, there are no holes, breaks, or cracks in the bead.

Image of a good welding pass with stick welding and 7018 electrodes
Vertical welding pass with 7018 – well-staked welding bits.

Good Stick Weld bead and Bad Stick Weld Bead

The appearance and quality of stick welding beads are affected by several different factors. Most commonly, these are current, voltage, and travel speed. If you’re welding with an amperage set too low, your electrode will be especially sticky when striking an arc.

Meanwhile, too high amperage will make the puddle excessively fluid and hard to control. This can lead to excess spatter and a higher potential for an undercut. The optimal Stick arc length is the same as the diameter of the electrode.

A short arc will create greater potential for the electrode to stick to the base material, and too-long arc results in a spatter with a possible undercut. Let’s take look at the visual representation of good and bad Stick welds.

Good finishing welds that passed inspections on plates and pipes:

Pipe fitted vertical downed position multi-pass weld with 7018 electrodes and good finish that passes visual inspection.
Pipe fitted vertical downed position multi-pass weld with 7018 electrodes and good finish that passes visual inspection.
Horizontal 2F and Vertical 3F with 7018 electrode - multipass. Passed visual inspection
Horizontal 2F and Vertical 3F with 7018 electrode – multipass. Passed visual inspection
Vertical 3G stick weld (7018) in multipass on the oil tank. Passed x-ray and visual inspection.
Vertical 3G stick weld (7018) in multipass on the oil tank. Passed x-ray and visual inspection.

Bad welds and common mistakes:

long vs short stick travel
Long vs Short Stick travel
low vs high stick current
Low vs High stick current
short vs long stick arc
Short vs Long Stick arc

TIG welding and TIG welds

Gas tungsten arc welding is one of the most complex and challenging welding processes to master. Beginners can agree that achieving a good TIG weld might be a nightmare, but it is one of the most suitable methods for welding delicate aluminum parts.

A clean TIG weld is one of the prettiest welds you’ll see.

Tungsten inert gas weld is made of many tiny welds neatly layered on top of each other, which look like stacked dimes. As a result, there is no slag or burnout.

high-quality TIG weld

Even though different welding methods yield different results, everyone can agree TIG produces aesthetically pleasing welds. On the other hand, a bad weld is pretty easy to notice as it is very wide with no distinct pattern to it.

Good TIG weld and Bad Weld

Many different factors can affect the appearance of the TIG weld, and that’s the main reason TIG welding is considered challenging. Most commonly, issues happen due to incorrect type or size of filler metal, lack of weld preparation including cleaning, and incorrect amperage.

Since we explained how each one of these factors affects the weld appearance, let’s look at bad welds.

Single pas with TIG in 2F position without mistakes.
Single pas with TIG in 2F position without mistakes.
TIG-welded pipe with root pass in 5G welding position with a great finish with no mistakes.
TIG-welded pipe with root pass in 5G welding position with a great finish with no mistakes.
Root pass on pipe viewed from the inside. Weld has some consistency problems on stops but it passes visual tests.
Root pass on pipe viewed from the inside. Weld has some consistency problems on stops but it passes visual tests.
TIG amperage too low
TIG low amperage
TIG filler too big
TIG porosity
porosity in TIG weld
TIG filler too large

Oxy-acetylene Gas Welding and Weld Beads

Besides Stick welding, oxyfuel gas welding is one of the most economical processes. Even though it was widely used in the past for joining copper alloys, the latest welding methods have surpassed it. In this process, oxygen and acetylene gas produce heat input that melts the base metal, joining autogenous or adding filler metal.

Regardless of the fact that OFW is not widely used today, a professional welder can still produce quality welds. For example, a good oxyacetylene weld includes a uniform bead with no holes or globules of melted metal.

Good and Bad weld Produced by Oxyfuel Welding

The appearance of the oxyfuel welding line can be affected by several different factors, such as flame type, weld metal, dirt on the weld surface, and welding torch manipulation. Nonetheless, here are some examples of good and bad welds.

Good oxyfuel weld
Good consistent oxyfuel weld with no undercuts.
Poor oxyfuel weld
Poor oxyfuel weld

Good Weld Vs Bad Weld – What Factors Affect The Weld Quality?

Many factors can affect the weld quality, and they can vary in the welding process. However, we will explain the crucial factors that are responsible for either good or a lousy looking and inadequate weld.

Most commonly, voltage, travel speed, the current selection, wire electrode feed speed (for MIG welding), filler metal size, and shielding gas distribution can affect the weld quality.

Selecting Proper Voltage

The first thing you should know is that voltage determines the height and width of the bead.

However, too much voltage is marked by poor arc control, inconsistent penetration, and a turbulent weld pool that fails to penetrate the base material consistently.

On the contrary, too little voltage results in poor arc starts, control, and penetration. It also causes excessive spatter, a convex bead profile, and poor tie-in at the toes of the weld.

To get the voltage right, you should follow the manufacturer’s recommendations for the given material.

If there are none, you should practice on scrap metal until you get it right.

female welder setting voltage

How Does Travel Speed Affect The Weld Quality?

Your welding travel speed should allow you to keep the arc in the leading one-third of the weld pool.

Too fast travel speed will result in a narrow, convex bead with inadequate tie-in at the toes of the weld, insufficient penetration, and an inconsistent weld bead.

Meanwhile, traveling too slow introduces too much heat into the weld, resulting in an excessively wide weld bead and poor penetration. On thinner material, it may also cause burn-through.

MIG welding traveling speed

Wire Feed Speed/Amperage

Setting the wire feed speed or amperage too high (depending on what type of machine you’re using) can cause poor arc starts, and lead to an excessively wide weld bead, burn-through, excessive spatter, and insufficient penetration.

Meanwhile, a narrow, frequently convex bead with poor tie-in at the toes of the weld marks insufficient amperage.

Shielding gas and Cleanliness

When dirt or oil on the base material vaporizes and forms a gas pocket in the weld pool, leading to defects such as porosity. The porosity and pinholes easily identify a lack of or inadequate shielding gas in the face and interior of the weld.

Breeze or draft may blow the shielding gas away from the weld pool and cause porosity, so you make sure to protect it. In addition, higher gas flow can create turbulence, which pulls the outside atmosphere into the weld pool, leading to contamination.

image of shielding gas cylinders

Filler metal Selection

One of the primary goals of weld preparation is matching the TIG filler rod, MIG filler wire, or stick welding electrode composition to the base metal. Besides compositions, welders should match the thickness of the filler according to the root opening.

Keep in mind that an oversized filler rod will not generate enough heat energy to raise its temperature fast enough to allow it to melt smoothly into the weld pool. On the contrary, the too-small rod will be consumed so quickly that a consistent weld bead will not be possible either.

image of TIG wire

Manipulation of the Electrode

Sophisticated welding techniques such as TIG welding require quite skilled electrode manipulation. Even though each welder can develop its style, electrode manipulation is crucial when willing more extensive roots.

Even though you can use the straight technique for more minor welds, lousy manipulation in the thicker openings will result in the poor-quality weld.

Resources

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Adam Mason

Welder by trade for a decade and more. Now also a web designer and a blog owner. Doing product reviews and writing blogs about welding trade and perks and minuses of being a welder.

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