Mild steel (also know as plain-carbon steel or low-carbon steel, something we’ll go over later in the article) is iron that contains small percentage of iron, which makes it strong but not readily tempered. But, we will elaborate on this a bit more throughout the remainder of the article.
Properties of Mild Steel / Low Carbon Steel
Mild steel is known for being low in carbon (hence the name Low-Carbon Steel) and tends to be cheaper and easier to make. The carbon content that you’ll typically find in a piece of Mild Steel will typically range from .05% to .30% depending on the weight which makes it ductile. On the other hand, high carbon steel will typically have a carbon count of .3% 2%. If the steel has a higher carbon count than that it would have to be called cast iron. Mild steel is not counted as an alloy which means that one won’t find many other alloys included in it’s makeup.
*you can improve the surface hardness of mild steel via carburizing
Due to the fact that Mild Steel has a lower carbon count it is known as being more weldable, and machinable that higher carbon steels.
*The carbon content that you’ll typically find in a piece of Mild Steel will typically range from .05% to .30% depending on the weight which makes it ductile.
It also means, however, that it is almost impossible to harden and make stronger through quenching and heating. The lower carbon count also means that it has less tensile strength than both alloy and higher carbon steels. Also take note of the fact that Mild Steel has a vast amount of ferrite and iron, which makes it magnetic.
*Ferrite is a solid solution phase of carbon that’s dissolved in alpha-iron, which is a body-centered cubic crystal (You can learn more about body centered cubic crystals here)
Not having alloying materials in it’s makeup means that improperly coating mild steel will result in the appearance of rust. The great thing about mild steel not having alloying materials is that it is incredibly affordable. The price of mild steel as well as it’s other characteristics is a major contributing factor to its popularity among welders.
How exactly do they make Mild Steel?
The process of making Mild Steel isn’t that much different from the process of making other carbon steels. For the most part, it’s made with both iron ore and coal. After the materials are taken from the ground they are blended together using a blast furnace. After the initial melting, they are moved to another furnace to get rid of any impurities in the combination as well as make the necessary adjustments to the mild steel chemical makeup. After the melting is finished the mild steel cools and is molded into a rectangular shape. Using both hot rolling and cold drawing the rectangular mild steel is brought down to the necessary size.
What is Mild Steel used for?
Below are a few of the basic applications of Mild Steel:
Many people believe that learning how to weld can help them find and settle down on a career. This is a true assumption – especially if you seek to become things such as Welding Inspector or an Engineer. Before you’re ready to hop into a career of welding you have to understand that it doesn’t immediately make things easier. There will be a fair number of hardships that are accompanied by this occupation. In addition to this, there are quite a few things that you as a future welder should make sure that you understand before you get started.
1. A welding degree isn’t much like a 4 year college degree
Welding is very much a hands-on learning experience. You’ll have to spend quite a bit of time learning on your feet. For the most part, you’ll have 2 different experiences during your time in a welding class. First, you’ll have to spend quite a bit of time learning in the classroom-basically so you can learn the theory behind it all. Next, you’ll have to learn in a workshop. This is what we call a lab and it gives you time to practice with the equipment you’ll be using to weld. While this is a great setup for those who learn best through practice, it does mean that it wouldn’t be very beneficial for you to begin skipping class.
2. What is hand-on-work exactly?
Welding equipment isn’t very simple to use – there are a wide number of buttons on the machines that need to be adjusted and calibrated in order for the machine to be used properly. In the lab you’ll have to use the machine – which will give you more time to use the machine and figure out how to use it. In the lab you’ll learn how the application of angles works and how the bead on the weld can be made better. In addition to this, in class you’ll have to perform quite a bit to pass certification exams that you’ll be forced to take.
3. Do you really learn how to weld from a book?
It can really help a budding welder to know the theories behind what they learn in class. Understanding why certain things happen when they’re welding can be really beneficial to making a person an overall better welder. It can also help a person avoid certain issues that tend to arise when they’re welding.
4. How exactly can someone grade you on welding?
When you take a course on welding you get tested based on things that you learn both from your teacher and the book. You’re also give a project that contains aspects given to you by a professor. After these things, you’re then graded based on you welding according to standards given by the AWS.
5. How helpful is learning how to weld in a college setting vs. in another area?
There are actually quite a few ways to learn to weld. The downside is that a number of welding positions require you to have a degree. Positions such as Engineer or Welding Inspector can take at least 12 years to obtain without getting a degree. College also gives you several soft skills that makes you more of a prospect such as the ability to communicate or an understanding of costs.
6. Is college really for you?
Welding isn’t the easiest thing in the world to study – but nothing in the world is really easy. If you’re interested in learning how to weld though, it can be beneficial for you to study welding. If you want to get a jumpstart on your education, it can be helpful for you to get familiar with the tools involved. Don’t worry though, while it may seem futile to get a degree in welding it is actually beneficial for you to do so.
7. There are several welding processes
There are a number of welding processes, ranging from Forge welding all the way to Gas Tungsten Arc welding (GTAW). We won’t go too deep into detail on the different types of welding because we have an article here that goes into detail on all of them.
Forge Welding
Video credits to Mitchel Jacobsen. It explains the process of Forge Welding.
Flux-core Welding
Video credits to Weld.com. It explains the process of Flux Core Arc Welding.
Electroslag Welding
Video credits to Engineer’s Academy. It explains the process of Gas-Metal Arc Welding.
Gas Metal Arc Welding
Video credits to Weldtube. It explains the process of Gas-Metal Arc Welding.
Gas Tungsten Arc Welding
Video credits to Weldnotes.com. It explains the process of Gas-Tungsten Arc Welding.
MIG Welding
Video credits to Weld.com. It explains the process of Submerged Arc Welding.
Plasma Arc Welding
https://www.youtube.com/watch?v=JM5CnQDelpE
Video credits to Jordan Smith. It explains the process of Plasma Arc Welding.
Shielded Metal Arc Welding
Video credits to Weld.com. It explains the process of Stick Welding.
Submerged Arc Welding
https://www.youtube.com/watch?v=xo7gSbEtWlY
Video credits to Jordan Smith. It explains the process of Submerged Arc Welding.
8. Safety isn’t optional
Essentially, you must be safe when you’re welding, at least if you want to have a long welding career. You want to make sure you have the correct gear, pick an adequate location, as well as do a few other things to make sure you won’t harm yourself or others.
Tack welding is a temporary way to hold welding components together, making sure each component stays in the same position, maintains alignment, the same distance, etc. until you can finish welding. Tack welds are a great way to set up welds without using fixtures and are typically very short welds.
Tack welding is usually done using the same type of process used for the overall weld. An example of this would be the way electron beam tack welds (made with less power) are done for welds done with electron beam welding. Also, if the final weld is done while the pieces are still clamped in fixture tack welds are used to keep each element in place and help reduce the stress. of each component.
What are the Advantages of Tack Welding
Tack Welding offers several benefits such as those listed below.
Benefits of Tack Welding:
Tack Welding is relatively straightforward as there is very little need for fluxes or filler metal. Nor is there a large open flame.
It doesn’t take an incredibly large amount of skill to learn tack welding.
Video credits to Redwingsteelworks. He demonstrates what he says is the right and wrong way to tack weld.
What are the disadvantages of Tack Welding?
There is usually both an upside and downside to performing a particular action. Tack welding is no exception to this. below are a few of the disadvantages of tack welding.
The electrodes must be able to reach both sides of the metal being joined.
Warpage can occur at the part where the weld is being done.
The metal may be less resistant to corrosion.
Issues / Tips for troubleshooting tack welds
Many people think that tack welding is the easiest method of welding to learn. It isn’t. In fact, many people actually tack weld the wrong way, they just don’t know it. Many of the errors they perform on their welds don’t show at first. This is why many simply overlook the troubleshooting process when they do tack welds.
Below are 3 tips for troubleshooting your tack welds:
People often worry about the amount of tack they’re using on their welds. This is why many welders refuse to use enough tack on their welds, they simply let the tack rest on the top of their welds rather than forcing them to penetrate the weld. This is the main reason why many welders welds aren’t relatively strong at all.
If you don’t use enough heat to fuse both of the pieces of metal then your weld won’t stay. In fact, if you make adequate use of your clamps and make sure to place your tacks in the correct spots, then you won’t have to worry about whether or not you’re tacking too much.
If you think of your tacks as simple, quick welds then you likely won’t be able to penetrate your metal thoroughly. Just as in a normal weld, tacking requires penetration in order to really work. To make sure you fully penetrate your metal, you can make sure to weld in either a u-shaped or circular motion – which ensures that your welds end up being even. Just make sure to reach the goal of welding, which is to make sure that your welds stick.
Tip 2. How to handle warpage
Much like freezing water, when you heat metal the molecules expand. When the metal cools it then contracts in a place completely different place. This is one of the main reasons why it’s such a pain to weld metal at 90 degree angles. The metal changes every single time you apply high levels of heat to it.
When you want to avoid the effects of warping, you typically think that performing quick tacks will get the job done. This can actually do much more harm than it does good. Instead of doing this it makes much more sense to pay attention to the place where you place your tacks. To make sure that your tacks are solid make sure that they are placed evenly around the metal.
Tip 3. Remeasure after you clamp
Many think that performing a tack on metal will take away the need for clamping, that’s not the case. When you clamp instead of tack you can avoid the warping issue that tacking can cause on a weld. The benefit of clamping is that it can take away the chances of warpage affecting the weld itself. If you don’t clamp the metal, then it’ll likely move around while you weld which will result in error.
Keep in mind that the clamps won’t completely eliminate the shifting that occurs during a weld. You should always make sure to measure each side after tacking to make sure that you can catch issues early. If you do, then you can apply methods which will allow you to fix the weld. If you don’t check your measurements after tacking, then you won’t be able to know whether or not you’re placing them in the correct place which can result in an incorrectly placed weld.
In short, if you want to make sure that you’re tacking correctly perform the above actions and makes sure you tack, this will result in adequate welds that perform to your satisfaction.
What makes tack welding important?
Although tack welding is temporary it is still just as important as the main weld. Tack welding is important because it does the below things for the weld:
It makes sure pieces are aligned.
It maintains the joint gap
It contrasts and controls distortion and movement in welding
In many ways, when you purchase a welding power source you have to make sure that you look at all of your options, because there are a few of them. You have to make sure that the piece of equipment you purchase has enough juice, is efficient, and fits all of your needs. To speak more clearly, the variables that come into play when you choose a power source are:
The current you’ll need
Level of convenience you need
The power available to use
How much you’re willing to spend
The process/es used: You’ll figure out the process/es to use when you know the base materials you’re going to use.
3 General Power Source Types for Welding
AC Transformer
Transformers are electrical devices that use induction to pass AC signal between circuits (they typically change the voltage and electric current while doing so).
AC/DC transformer rectifier
AC/DC transformer rectifiers are electrical devices that converts AC (alternating current), to DC (direct current) through a process called rectification.
DC generator and inverter
An inverter is a method using a direct current (DC) to produce an alternating current (AC). They draw power from sources such as solar panels and use electronic circuits to turn / “invert” the DC into an AC.
Below are a couple welding processes and the typical power source used
MIG Welding Power Sources
For most MIG welding direct current, constant potential power sources are used. MIG welding uses power sources offer the arc (when welding) a constant voltage. The voltage then determines the arc length.
When there is a sudden change in arc length or wire-feed speed the power source you use will increase/decrease the current. This change will either cause the current to increase or decrease depending on the change in arc length (this also effects the wire burn off rate). The burn off rate will actually adjust automatically to restore the original length of the arc.
With that, if you want to make a change in the arc length you can make a permanent change in the output of your power source.
Other Considerations
There are a few variables that must be taken into consideration so you can control things such a spatter, heat, etc.
These variables are:
Slope: The slope of the power source refers to the way an increasing current cause output voltge to decrease. The slope of the power source isn’t the slope of the arc system.
In MIG welding the slope is used to limit the short circuit current which helps reduce spatter when short circuits between the workplace and wire electrode are cleared. Greater slopes have lower short circuit currents and less spatter (with limitations).
Inductance: When inductance is introduced to a weld it helps to reduce spatter in the weld.
Voltage: The Arc voltage is the voltage between the workplace and the end of your wire. You cannot read arc voltage on your voltmeter because of voltage drops you encounter in your welding system.
Arc length or welding voltage plays a large role in choosing which type of metal transfer chosen. For example, short arc welding needs much lower voltages compared to spray arc welding which requires higher voltages.
TIG Welding Power Sources
TIG welder power sources can actually be either AC or DC – however, in both types the output is called drooping/constant current. This means that the welding current and arc voltage relationship has a constant current for any power source setting.
Length of the arc has a direct relationship with consistency of the welder’s ability to hold the torch above the workpiece. Not only that, but there is also a relationship between arc length and arc voltage – higher voltage means you have a shorter arc and vise versa. TIG power sources are designed to have a lower range of current as well as a reduced variation on changing voltage.
DC Power Source
DC power sources produce a concentrated arc with the majority of it’s heat being placed in the workpiece, making it a great power source for welding. Arcs with their cathode roots on the electrode result in little cleaning of the workplace surface.
AC power source
Materials such as aluminum have an oxide film on their surface, which means that an AC power source must be used. When you switch between negative or positive polarity, the periods when the electrode is positive both cleans the surface and removes the oxide.
Shielded Metal Arc Welding Power Sources
Manual Metal Arc welding or Shielded Metal Arc welding needs a power source that is capable of giving a constant current even if the arc experiences voltage changes due to small changes in the length of the arc.
Submerged Arc Welding Power Sources
SAW can be operated with either an AC or DC power source. AC is supplied by a transformer and DC is supplied by a transformer-rectifier. The current for a single wire will range from, at a low point, 200A (1.6mm diameter wire) to around 1000A (6 mm diameter wire). Generally speaking, welding is usually done on a thick plate where single wires are normally used over a limited range of 600 to 900A, with twin wire systems operating between 800 and 1200A.
Many consider welding to simply be an activity that requires multiple pieces of metal to be joined together by some form of heat. This is typically true. The application of heat to metal allows them to have enhanced malleability which also allows them to be joined together in a single joint – don’t forget that when the heat is applied, one must also apply pressure to the pieces of metal to make sure that they are joined. Welding has been around for quite some time. Before it was known as the “welding” that we know it as it was called “forge welding” which basically meant that 2 pieces of metal were being joined together.
In short, forge welding required the welder to use an open flame to develop enough heat to make the metals that were meant to be welded malleable. Eventually, this method of welding began to die out. As energy sources were harnesses gas and electric welding methods were harnessed to keep the welders safer in the workplace. More tools than we care to think about have been created by welders. This is because of the wide applications that welding has in construction as well as in everyday life.
Welding is a process that has a wide variety of application to everyday life. It’s important to keep in mind that these applications also require that each of the welding processes be diversified.
As well as a few others. Below, we’ll go over each type of welding (the broad type) as well as a few subcategories.
What is Arc Welding?
Arc welding is a fusion process that uses an electric arc from power supply (either AC or DC) that creates a heat around 6500 degrees Fahrenheit which melts the metal at the joint. One can guide an arc mechanically or manually along the joint.
Metals used in arc welding react to the nitrogen and oxygen in the air when they’re heated to the degrees possible by the arc. To help prevent the negative effects of the reaction to the metal, a slag (protective shielding gas) is used to reduce the weld’s contact with the air. The weld is finished to once it cools and solidifies.
Video credits to Weld.com. It’s a very thorough introduction to arc welding.
Arc Welding sub-types
[table id=98 /]
What is Oxy-fuel Gas Welding?
Oxy-fuel welding is a blanket term uses to describe welding processes that use the combustion of both Oxygen and fuel to produce enough heat for fusion welding. Oxy-fuel processes entail the use of a flame (that’s produced near the end of the welding torch) to melt the parent metal with / without filler metal. The actual fuel and gas are placed inside of a chamber where they’re mixed (this chamber is a part of the welding torch.
With oxy-fuel welding you may relinquish a few of the benefits that you get with arc welding but, you receive some of the following benefits:
Welders get decent control over the heat input, filler metal addition, and temperature (all independently)
The flame chemistry can be altered from carburizing through neutral to oxidizing.
Equipment is relatively inexpensive and portable
Oxy-fuel Welding sub-types
[table id=99 /]
What is Resistance Welding?
Resistance welding is the process of joining metals through the application of pressure and a current for a period. The advantage of resistance welding is that one doesn’t need anything other than the materials used to create the weld (it’s an economical choice).
Resistance Welding sub-types
[table id=100 /]
What is Solid-State Welding?
Solid State Welding is a joining process that doesn’t have either a vapor or liquid phase. Not only that but it uses pressure and doesn’t have to use temperature. For solid state welding to take place the cohesive forces between atoms and metal are used.
There is no better time than the present to get interested in a career in welding.
Regardless of the are you’re in, the fight for clean energy will be in a constant rate of growth. Eventually, we will be living in an entirely green economy, it’s inevitable. The thing to pay attention to now are the fields that’re going to make people the most money.
A few examples of green energy sources are:
Ethanol
Solar
Natural Gas
Water
Wind
Etc.
Considering there are so many industries where green energy is so important, it makes sense to simply look for the common denominators in all of the industries. Now, since we know that developing a society to the point where they could utilize each of these methods on a full scale would require a lot of metal we can deduce that the best filed to be in would be one that requires constant interaction with metal. One of the fields we know has this requirement is metal fabrication or welding.
Welding is what many would call a green collar job – one that has a huge demand even in our economy. It is incredibly challenging to find a welder with enough skill to complete complicated projects, which is why it’s so profitable to learn and be skilled at welding.
It’s important to keep in mind that welding is a job that is profitable to work in even without the green industries. There are a number of welding jobs available to talented welding professionals. When the green energy initiative goes into full swing, it’s important to make sure that you have already learned enough about welding to be considered a skilled individual. Once it does take off, companies will be willing to pay much more than they currently do for welders. Many companies already have training areas set up to train their own skilled metal fabricators. It’s important to be good enough at fabrication that you’re able to perform at a high level in almost any area of welding.
Not only is welding an area where individuals have the capability of working in green areas but welders also have access to a wide number of other things.
Such as: Traveling all over the globe
Working in exotic areas
Making more money than those in the most esteemed positions
Making a difference in their community
Other Green Collar Jobs To Watch Out For
[table id=94 /]
While none of us really know what energy solutions will actually make it, we can be sure that whatever does make it will require a welder. If the ability to push the world into sustainability isn’t enough to motivate you into action, how about the ability to make 6+ figures without having to get a four or more-year college degree?
In an earlier article we mentioned that all exceptional welders have basic math skills. These skills are necessary if you plan to ever get good at the craft, for reasons that may not be so obvious. In reality, when we say fitter math we are referring to the basic algebra that we are forced to learn in a high school setting. The fact of the matter is that it’s kind of challenging to weld properly and pick up jobs if it’s difficult for you to measure angles and perform simple calculations.
Just remember, it isn’t as hard as you think
It’s common knowledge that many people get frightened when they see even a bit of math. In reality, we all think that things that involve math require us to do things the “hard” way. In reality, when you force yourself to perform trial and error experiments all of the time because you don’t know the formulas that will get you the exact measurements you need to get it right the first time you try. When you first look at fitter math we ask that you do one thing, keep an open mind. It isn’t as hard as we make it seem.
As with welding, when you first approach fitter math you have to be incredibly patient. You likely won’t get it right on your first try but as you keep learning I’m sure that you’ll figure it out. Despite the fact that it will save you quite a bit of time, it will also make sure that your clients are always happy with the work you do for them.
The connection between reading blueprints and fitter math
Before we open up on this section of the article, we ask you one thing – when you first start looking at blueprints don’t think everything is about the symbols, because it isn’t.
Why? Because welding is not all about knowing welding symbols – it’s more about knowing the math that goes into welding. We say this because it’s much easier to weld if you know how to weld efficiently, which means, with math. The symbols that are apart of welding can easily be learned on the job, the math can’t.
Keep in mind that when you’re welding many of the blueprints that you come into contact with won’t have the exact reference points that you need. Another thing to keep in mind is that a majority of engineers also make the mistake of overlooking certain key details that are necessary for the weld to be performed. Don’t blame the engineer because they also have tight schedule and relatively large workloads. When you first get your hands on a new blueprint it’s helpful to take a seat and figure out exactly where you’re likely to run into an engineer induced mistake.
It may not seem like it but, fitter math is probably the best option you have
If you want to save yourself sometime in the long run learning fitter math is probably your best choice. If you want to spend a great deal of time on each and every one your projects, then continue using the trial-and-error method of fabrication. If you want to be precise in your movements, then we suggest that you learn fitter math.
Welding is a process whereby metals and other materials are pieced together using pressure – this pressure can sometimes be utilized to create beautiful things. The pressure used in welding is pooled together with heat to change the shape of the materials being welded to the desire of the welder. To piece the metals together, the welder must use filler material that is compatible with the weld so as to make sure that a solid weld joint is formed. Welding is a simple process; it’s intended to join multiple pieces of metal together to form something more. On the other hand, there is a process called structural welding that requires a bit more skill than basic welding. This is because of the variety of colors and shapes that are involved in the process.
Who are a few metal fabrication artists?
Listed below we have several famous metal working artists and links to their respective websites.
As with any process, you are bound to encounter defects in the process. You can encounter things such as misshapes and off sizing of the metal. This can occur due to either a bad welding process or bad technique. Listed below are the most common defects that you’re likely to find.
There are 2 types of welding defects: External Welding Defects and Internal Welding Defects.
Overlap is the considered a protrusion of weld metal beyond the weld root. Overlap typically occurs in butt joints and fillet welds and results in notches occurring at the toe of the weld. These notches are undesirable due to the stress concentration that occurs under load. These discontinuities are caused by either insufficient current or incorrect welding technique.
How does overlap occur in welding?
Overlap in welding occurs when the molten metal from the weld flows over the surface of the base material and then cools without fusing to the base material. A common cause of overlap in welding is having too much weld metal supplied because of the weld speed being too low. When there is overlap in fillet welds it’s typically caused by the effect of gravity on excessive molten metal.
How do you fix overlap in welding?
To avoid overlap you must make sure to review your welding settings (welding speed and current).
Video credits to Weld.com. It goes over ways to prevent weld overlap.
Spatter
What is spatter in welding?
When you have particles that attach to the surrounding areas of the surface the result is spatter. Surprisingly it’s pretty common in welds done with gas metal arc welding. It’s also one of the defects that you can’t completely eliminate, no matter how hard you try. It is, however, possible to keep its occurrence as low as possible.
How does spatter occur in welding?
When your amperage is too high
When the setting of voltage is too low
When your welding surface is contaminated
When your arc is long
When you have an incorrect polarity
How do you fix spatter?
Make sure you welding surface is clean before you weld
A serious complication that many welders tend to encounter during the process are cracks in the weld. These cracks can manifest anywhere in the weld, such as in the metal, on the surface, or anywhere else that touches the heat of the welder.
The different types of cracks are:
Heat cracks
Cold cracks
Crater cracks
What are heat cracks in welding?
These typically occur in the crystallization portion of the welding process. Temperatures of the metal at this point typically rises to over 10000C
What are cold cracks in welding?
These types of cracks typically show up after the weld has been finished. They can sometimes take longer than average periods to show and will manifest as slight deformities in the metal.
What are crater cracks in welding?
These types of cracks tend to show at the end of the entire process and occur at the end of the weld. When there is not enough room at the end of the weld for shrinkage of the weld metal a crater crack forms.
Why do welding cracks occur?
When you use hydrogen while welding ferrous metals
When there’s residual stress from the solidification shrinkage
When the base metal is contaminated
When you are welding with a high welding speed but with a low current
When you don’t preheat before you weld
When there’s a bad joint design
When there’s a high sulfur content and alot of carbon in your metal
Make sure that the gas flow to the machine is properly adjusted
Reduce your arc travel speed
Make sure you have the correct electrodes
Weld with the correct technique
Video credits to Miller Welders. It goes over how to fix porosity in your welds – The right way!
Undercut
What are undercuts in welding?
When you have a groove formation at the weld toe you come into contact with this imperfection. When you have an undercut you have a weakened weld.
Why does undercutting occur?
When you weld with too high a current
When you weld to quickly
When you use an incorrect angle when you weld
When the electrode you weld with is too large
When you use an incorrect amount of shielding gas
When you don’t have the right filler metal
How do you fix undercutting in welding?
Use the correct electrode angle
Make your arc length shorter
Weld with a lower electrode travel speed
Weld with the correct shielding gas
Use the right electrode angle
Video credits to Herbert Bartley. It talks about how to avoid undercut in welds.
What are Internal Welding Defects?
Unfinished Penetration
What is Unfinished Pentration in welding?
When the groove of the metal isn’t filled completely the result is an incomplete penetration. This also means that the weld metal won’t fully extend throughout the thickness of the joint.
How do unfinished penetrations occurs?
When there is to much space in the metal you’re welding
When you move the bead too quickly
When you’re using too low of an amperage setting
When there is too large of an electrode diameter
When there is an improper joint
How do you fix unfinished penetration in welding?
Make sure to have a proper joint geometry
Have a properly electrode size
Reduce your overall arc travel speed
Make sure to have the correct welding current
Have the correct alignment
Video credits to Kevin Caron, Artist. It goes over way to make sure you get good welding penetration.
When you neglect to clean the weld pass and move on to another one.
When you have an incorrect welding angle
When your weld pool cools too quickly
When the current you use to weld is too low
How do you fix slag in the weld?
Make your current denser
Fix the cooling rate of the weld
Fix the angle of the electrode
Remove the slag from the bead
Fix the speed of the weld
Video credits to xAZAZELx13. This video goes over how to repair slag in the weld.
Unfinished Fusion
What is unfinished fusion?
When there isn’t a proper fusion in the base of the weld and in the weld metal you have an improper fusion. You can also find this in the adjoining beads of the weld. When you have unfinished fusion, you have a weld with gaps that don’t have molten metal in them.
Why do unfinished fusions occur?
When you don’t have enough heat
When the surface of the weld is contaminated
When you have an incorrect electrode angle
When you weld with too fast a travel speed
How do you fix unfinished fusion?
Make sure to use the correct arc voltage for your weld
Clean the metal before you weld
Keep the molten metal from flooding the arc
Lower your disposition rate
Necklace Cracking
What is Necklace cracking in welding?
Necklace cracking occurs when the electron beam weld doesn’t fully penetrate fully and a blind weld occurs. In these instances molten metal neglects to flow into the penetration cavity and onto the side walls of the workpiece. This occurs in metals such as is carbon steel, nickel base alloys, stainless steel, titanium alloy.
What is the cause of necklace cracking in welding?
The common causes of necklace cracking in welding are:
In short, cold welding (aka contact welding) is a solid-state welding process that bonds 2 pieces of material together by applying pressure to them both. The pressure applied to the pieces of metal breaks up the oxide layers and allows the two pieces of material to stick to one another. You don’t have to worry about applying heat to or melting materials with cold welding.
Pros
Reduces the necessary skills for welding exotic metals
Makes it possible to join a number of metals that are dissimilar and would be otherwise difficult to weld
Gives a near perfect welding joint without brittle intermetallic compounds, microfractures, and other joint weaknesses
Eliminates most heat affected zone (HAZ) problems since there is no concentrated heat and because of this, no HAZ, from the welding arc
Is a perfect process for welding aluminum, especially in joining copper with aluminum, two metals that would typically be a challenge to join with other welding processes
Cons
It is difficult to weld irregular shapes, and the best results are gotten with flat surfaces
Difficult to achieve in industrial settings because of the debris that float in the air
Carbon steel and hardened metal can’t be cold welded, this only works with non-ferrous ductile metal like copper, gold, aluminum, lead, etc.
Surfaces must be cleaned pristinely; meaning that multiple steps of cleaning may have to be taken and the metal may have to be prepped
Surface irregularities, contamination, and nanoscale molecular structures can hurt the results
How does cold welding work?
When you have 2 pieces of material without a solid oxide layer, the atoms on the exposed sides of the materials collapse into one another. This is essentially how cold welding works. The union of the two materials can fail if they are in either a reactive or oxygen intense environment. For cold welding to be effective both surfaces must be cleaned thoroughly and free of contaminants.
Video credits to Cody’sLab. It demonstrates (or attempts to demonstrate) cold welding in a vacuum chamber.
For cold welding to work the two surfaces being welded must essentially be both clean and flat (anatomically so). The bond produced will be equal to the strength of the parent metal.
What metals can be cold welded?
Cold welding can only be used on non-ferrous metals or soft iron with no carbon content. The most common metals used for cold welding are aluminum and copper. However, there are other metals one can use such as:
Cold welding is typically used to weld wires together, especially between metals that are dissimilar. This method of welding is great when one is laying underground wires and there is the danger of flammable gasses catching fire from welding processes that are heat inducing.
On top of this, this method of welding is used to seal containers that’re sensitive to heat, like containers with explosives for example.
Cold welding is generally used when heat will damage the product or may present a danger.
Requirements for cold welding
The main requirements for cold welding are prepping the joint’s geometry and a clean metal surface. Joint surfaces that are flat work best, so flattening any irregularities in the shape is what’s recommended.
The oxide layer and any other impurities can be removed by degreasing, wire brushing, or chemical or mechanical methods. There will typically be oil and grease on the surface of the metal that will have to be removed before wire brushing. This is necessary since the brush can force the impurities deeper into the metal. Thanks to the wire brush’s sharp bristles, soft metal like silver, gold, copper, aluminum, and many others are more susceptible to getting surface oils embedded below the surface.
After the oils are cleaned, one can continue to strip away the oxide layer itself. Varying with the metal, different brush types and bristle materials may be recommended. It’s always a good idea to check the metal’s specification sheet.
Is cold welding strong?
Colded welded joints are as strong as the parent metal if it is properly prepped. Joint strength varies with the metal’s properties. Unlike with other welding methods, cold welding joint strength can’t outperform the original metal strength.
Joint strength will be compromised if the joining surfaces aren’t cleaned sufficiently enough or are irregularly shaped. For typical cold-welding applications such as joining wire, the maximum bond isn’t very hard to achieve.
What are the possible weld joints?
Because cold pressure welding is best done on large contact surfaces, it’s best to use lap and butt joints.
Butt welds are typically used when welding pipes and wires together. This is because it’s simple to trim the ends, put clean metal onto the contact surface, and press the two wires together.
When you’re making a butt weld, the distance between the clamping points and the contact surface should not be too large since soft metals can always bend sideways rather than join together.
Cold lap joints can be tricky. By pressing sheet metal together you’ll reduce the thickness of it because of the applied pressure. Meaning that one should account for at least a 50 percent thickness when you’re prepping the project. Without that, the final part won’t meet the requirements of the project.
The project may be perfect, but the thinned part isn’t acceptable. One should consider the metals softness and ductility and perform a few test welds to determine the thickness that will occur as a result.
Machines that cold weld and can join wires
Cold welders are hand operated for wires with small diameters. But larger diameters need a pneumatic or electric-pneumatic operation. Many of these machines are portable and can handle strips, wires, and rods.
Making use of an air hydraulic intensifier, cold welders generate extreme pressure. On the operator’s side, there is a welding head. This is located on the top of the machine and serves to accept a welding die, control the applied pressure, and offer stability.
Once the die is placed and secured into the die pocket, rods/wires are then fed in on both sides. By applying pressure, one will cause the die to grip the wires near the endpoints and to push them tightly together. As a result of this, small impurities that remain on the wires cross-section surfaces are squeezed outwards from their cores. This is why cold-welding wires will create a better joint bond than when welding sheet metal. This is mainly due to the wires having a small joining surface area unlike with sheet metal.
Pressure is applied at least 4 times to get rid of all the impurities. This is considered the multi upset principle. Once the wires have bonded, one can remove them from the machine while chipping away the residue from around the joint area.
Hot welding vs Cold welding
Hot welding methods involve the use of an electrical arc, an active flame, or internal resistance to melt and meld the metal. Cold welding is better suited to specific applications and non-ferrous metal, while hot welding can be used for many more things.
Which metals can be cold welded?
The metals that can be cold welded include 70/30 brass alloy, silver alloys, silver, nickel, lead, zinc, aluminum, copper, gold and platinum. This method can also weld 7xxx and 2xxx series of aluminum alloy. These types of metals can’t be fusion welded because they will likely crack when under heat, and they are hard to weld together with welding methods outside of cold welding.
It’s impossible to cold weld carbon steel or any other metal that contain carbon. This will limit the cold-welding application because carbon steel is welded far more than most other metals.
Cold welding will work best with metals that have a face-centered cubic arrangement of atoms that won’t harden quickly. All of the metals that harden quickly tend to crack under the pressure felt when cold welding. This explains why only highly ductile metals can be cold welded.
The different methods of cold welding
There are only 3 similarly named methods, no different cold welding types.
JB Weld
There is a brand epoxy bonding system that’s used with metal, fiberglass, brick, and concrete named JB weld. It doesn’t actually create a weld between metals but it’s called the original cold weld formula.
Unlike with the cold-welding process, there is no interatomic attraction, and the metals don’t fuse to because a single homogenous mass.
JB weld works well to adhere metal, but the metals won’t be welded together. The product is a 2-component epoxy, base, and an activator. When this product is mixed and applied to metal parts one should secure them with clamps and start the curing process.
This method has a tensile bonding strength of 5020 PSI, which is compared to the typical E6010 stick electrode that has a 60,000 PSI bond strength.
This is no substitute for an actual weld unless you plan on making small repairs around the house.
Cold Metal Transfer
CMT or Cold Metal Transfer is a fusion welding process that makes use of a welding arc to make a joint. It’s often improperly titled cold welding. CMT is a MIG welding process that needs about 90 percent less input of heat than regular MIG welding processes.
Because this arcwelding process is so “cold” it has solved many problems like with the actual cold welding process.
CMT shouldn’t be mistaken for cold welding though, as it uses an electrical arc, filler metal wire, and it can be used with metal with which cold pressure welding isn’t an option. CMT relies on a precise filler wire retraction arc initiation to control the heat input.
Because only a robot is able to do this, it isn’t economical if cold pressure welding is a viable option.
TIG Cold Welding
As with CMT, TIG cold welding is of no relation to the method of cold pressure welding. There are some TIG welding machines that have a cold setting that limits the heat input. It does so by applying an electric arc to a small spot for a fraction of a second.
Temperature is minimal since any generated heat will dissipate quickly, especially with metals that are highly conductive like aluminum.
This is especially useful when one is welding thin sheets of wires and metal. One could achieve something similar with an advanced TIG welder by using the pulse settings.
You will achieve low heat TIG weld by setting a low pulse current and a high time dilation between the pulses. Low heat isn’t always good enough, so if cold pressure welding is an option, it will produce a better joint.
History of Cold Welding
Cold welding started in the Bronze Age, around 700 BC but back then it wasn’t anywhere as sophisticated as it is today. Archaeologists have excavated a number of utensils and tools from that time period that were made using an older cold welding process.
The first documented scientific experiment on cold welding was done in 1724 by Reverend J.T. Desaguilers. He found that if he pressed and twisted two lead balls together, they would make a solid joint. He then tested the bond strength on a steelyard with positive results.
The next notable point in history was the second World War when light alloy aircraft parts were made using cold welding in Germany. As industry made progress, cold welding became more advanced and became what is today a well understood process used in specialized settings.
