How to Prevent Undercut In Stick Welding?

The most typical error made among welders, especially newbies is undercutting. However, you can never stop learning new ways to enhance your welding skills. In reality, this welding flaw is rather widespread, and it may be found in a variety of materials and joints.

As a result, people who are just getting started should have a rudimentary understanding of this undesirable fault to assist them to deal with it. Here in this article, you'll learn how to avoid undercuts when sticking welding and it'll explain what undercut is, what causes it, how to fix it, and how to remove it.

What’s an Undercut?

The undercut is a groove that forms by mistake with the welded joint. At the margin of the weld joint, there is a long dip in the base metal. We call it a funnel because it can physically hold fluid within. In summary, undercuts damage the weld in a variety of ways.

Assume you're welding a butt junction between two 5mm slabs. The welded joint and its rest of the area should ideally be at most 5mm wide. However, if it's an undercut then the width at the weld joint or base would be less than 5mm.

At certain places, the structural integrity of the joint is jeopardized. These low-thickness sections are usually the first to break under strain. By retaining excess water, an undercut reduces the strength of a joint. The trapped water increases oxidation in an already fragile location, causing the item to fail prematurely.

How Do You Prevent Undercut And Burn?

  • Apply the Correct Current: If you're seeing extended, persistent undercuts, reduce the current. To achieve correct fusion, this decreases overheating.
  • Make Use of the Appropriate Voltage: Select the most suitable place on the voltage slider for no undercuts, a clean finish, and a consistent bead profile.
  • Welding Should Never Be Done in a Hurry: Allow plenty of time for stirring and avoid early solidification by moving the stick slowly.
  • Fillers that are compatible: Before deciding on a filler material, check a table or an expert welder.
  • Maintain a Positive Work Attitude: Keep an inclination that properly distributes filler in the weld zone. This may be determined by looking at either face of the wedge and noting any changes.
  • Select the Right Electrode Shape: A good electrode fits into your groove well and distributes energy evenly.
  • Shielding that is Case-Appropriate: Make an educated decision based on the desired weld and make sure the gasoline composition is right for the job.
  • Thread with a firm grip: During weaving, gently pause at the margins to guarantee good fusing at these high-risk areas.
  • Ensure a Steady Arc: When there is excessive splatter or opposition to the movement then the arc length is wrong. Using these indications, adjust it and keep it consistent all through the welding.
  • Make ready the wedge properly: Maintain the proper fillet grooves, smooth them out, and clean them as professionally as possible.

What Causes Undercut In Welds?

Electrode Movement at High Speeds:

The effectiveness of the welding is mostly related to the rate and speed of motion of the electrode. If you use a fast velocity, the ultimate product will have multiple weak areas and insufficient metal fusion. The very weak molten metal with the welded zone is to blame for this poor result.

Heat Produced in Excessive Amounts:

When a strong current generates a lot of heat, it quickly rushes into the weld region, causing fast solidification. Slow solidification would guarantee that the molten metal was properly cured and fused. Rapid curing, on the other hand, favors rapid solidification, resulting in an undercut.

  • Inadequate Welding Technique:

Weaving is a technique in which the operator weaves the wedges together by moving the electrodes sideways. It guarantees that heat is distributed evenly over the weld region, resulting in consistent curing. When welding, make sure you have a good grip on the electrode. Because there is no appropriate fusion in the gap of both the welded metal and the base material when an undercut develops, the parent material melts improperly.

  • Lengthening of the Arc:

The arc is the distance connecting the electrode's tip and the weld's surface. There are four fundamental welding roles: horizontally, vertically, level.  The arc length variation is influenced by these points. A long arc length causes the more molten metal to be cast than is required, resulting in an undercut. Make sure the size is appropriate for your project's needs.

Incorrect size of electrodes:

Electrodes are available in a variety of sizes and styles. If you choose a big piece, the quantity of liquid steel deposited rises as well, resulting in an undercut. Similarly, if the electrodes become too tiny, the quantity of liquid steel deposited is inadequate, resulting in surface imperfections.

  • Positioning the Electrode at an Incorrect Angle:

Weld quality is greatly influenced by the angle at which the electrode is held. When the source substance is put on a flat surface, it is common to keep the electrodes in an upright direction. If the ground is unsteady, an undercut is more likely to form because the asymmetry of fillers stimulates the formation of an undercut.

Shielding Gas that has been contaminated:

Shielding gas that has been contaminated is being used to protect molten steel from corrosive infiltration. Possible agents include gases such as nitrogen, oxygen, and hydrocarbons, which can permeate the process and reduce porosity.

Wrong Filler Particles Portion:

Materials such as silver, aluminum, lead, and copper are frequently used in advanced welding procedures such as brazing and soldering. They enhance the joint's physical and structural qualities. A terrible decision of filler metal can be devastating since it might interfere with the joint's characteristics.

  • Surface Quality of Parent Material:

Prior to, throughout, or then after welding, it's always a good idea to keep your hands clean. Undercutting may be encouraged by improper hygiene. They generally behave like contaminants, interfering with the weld metal's crystallographic characteristics.

What Causes Undercut In SMAW?

A shielded metal arc weld (SMAW) weld is made by creating a sphere or an arc here between a number of electrodes and a filler metal. The disintegration of the shielding develops into fumes that protect the puddle while the welder gradually delivers the coated electrode through into the weld joint. Excessive current is one cause of this problem, which causes the margins of the junction to burn and flow into the welding, leaving a drain-like imprint along the weld's length.

Final Note

This undercut in stick welding is a difficult subject. It's difficult to avoid undercuts. With a lot of effort and time, there's no assurance that you'll never run across this problem again. So, if it does happen, you'll have to learn how to handle it like an expert. Additionally, do everything you can to avoid undercutting.

Last Updated on 1 year by Richard Boyer

  • June 8, 2022
Richard Boyer

Richard Boyer has been a professional welder for over 27 years of his life, and now he is a trainer and blogger providing critical information to anyone interested in welding. He is helping out both hobbyists, novice and professional welders to learn newer and better techniques. Read more about me

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