What is Undercut in Welding and What Causes It?

What is Undercut in Welding and What Causes It?

What is Undercut in Welding and What Causes It?

If you are a welder or work in the welding industry, you may have heard of “undercut” before. Undercut is a common welding defect that can occur during the welding process. Understanding what causes undercuts and how to prevent them can help welders produce high-quality, durable welds. In this article, we will explore the causes, effects, and preventive measures for undercutting in welding. Keep reading to learn more.

Understanding Undercut in Welding

Undercut in welding refers to a groove or depression that forms at the edge of the weld joint. This can happen when the molten metal does not completely fill in the weld groove, leaving an uneven or incomplete surface. These imperfections can weaken the weld, making it more susceptible to cracking or breaking. Luckily, undercuts are easy to spot. An undercut can often be seen as a small trench along the edges of the weld bead. Here are some ways this defect can be recognized:

  • A groove or depression along the weld toe.
  • A reduction in thickness of the base metal close to the weld.
  • Sharp edges or notches that can be seen and felt along the weld seam.

Undercutting can occur in all types of welding processes, including MIG/MAG, TIG, and stick welding. If you are a beginner welder, you may be more prone to creating undercuts due to a lack of experience or improper technique. However, even experienced welders can make mistakes that lead to undercutting.

Causes of Undercut in Welding

Undercutting can be caused by a variety of factors, including:

Welding Speed: Welding too quickly can prevent the molten metal from filling the weld area properly. You should maintain an appropriate speed to make sure the metal has time to flow and fill the joint well.

Incorrect Angle of the Electrode: Holding the electrode at an incorrect angle can cause the arc to focus too much heat on one side of the weld, melting the base metal without depositing enough filler material. The correct angle varies depending on the welding process; typically, a slight tilt toward the direction of travel is ideal.

Excessive Welding Current: Using current settings that are too high can form undercuts in a weld because it melts too much of the base metal. Welders should adjust their current to match the welding process, material thickness, and type.

Weak Welding Current: Using current settings that are too low can also result in undercuts because the base metal doesn’t melt enough to fuse properly with the filler material. Make sure to calibrate your current settings accordingly and avoid setting the current too high or too low. 

Insufficient Filler Material: It’s important to maintain a steady supply of filler material or else your weld joints may be underfilled, which increases the risk of undercuts.

While it is easy to read about the different factors that can cause undercutting, avoiding them while welding can be more challenging. Welders must have a good understanding of the welding process they are using and be able to adjust their technique accordingly. Regular practice and experience can also help identify potential issues and prevent undercutting.

Why is Undercut a Problem?

Undercuts can result in structural and visual problems that lower the quality and durability of the weld. Depending on the job and welding type, these issues can be a minor inconvenience or a major safety hazard. Here are some of the main problems associated with undercutting:

  • Decreased weld strength: Undercuts reduce the amount of metal fused together, weakening the overall strength and load-bearing capacity of the weld.
  • Cracking: Undercutting can lead to cracks in the weld due to stress concentrations at the edges.
  • Corrosion: The exposed base metal in an undercut is more susceptible to corrosion, which can compromise the integrity of the weld joint.
  • Brittle Welds: When undercuts occur in high-stress areas, they can result in brittle and weak welds that are prone to breaking.

Welders should always be vigilant and check for any signs of undercutting during the welding process. Catching and addressing it early can save time and money.

How to Prevent Undercut in Your Welds?

As mentioned earlier, preventing undercutting requires a good understanding of the welding process and proper technique. Here are some tips to help you avoid undercutting in your welds:

Equipment and Maintenance:

  • Quality Tools: Using high-quality welding equipment can significantly reduce the chances of defects. Invest in reliable tools that offer better control and precision. If you are a pipe welder, our tools can help you achieve consistent results.
  • Regular Maintenance: Regularly inspect your welding equipment to make sure it is in good working condition. Worn-out or damaged tools can cause welding defects.
  • Proper Storage: Store welding materials and tools in proper conditions to prevent damage. Moisture, rust, and other environmental factors can affect the quality of your welding supplies.

Proper Welding Techniques:

  • Maintain a steady travel speed to prevent insufficient fill or overheating.
  • Use a slight torch tilt to evenly distribute filler metal and protect the edges.
  • Fine-tune amperage and voltage settings to find the right balance between metal vaporization and penetration.

Training and Practice:

  • Skill Development: Invest time in developing welding skills through practice and training. The more experience you have, the better you will be at controlling the welding parameters and preventing defects like undercuts.
  • Welding Courses: Consider taking formal welding courses or attending workshops to improve your techniques. These courses often provide valuable insights into advanced welding methods and common issues.
  • Experienced Mentorship: Learning from experienced welders can be incredibly beneficial. Search for mentors who can offer tips and advice based on their own experiences.

These are some of the best methods used to prevent undercuts and strengthen your welds. However, don’t get discouraged if you encounter undercuts occasionally. With practice and experience, you will be able to identify and fix them quickly, resulting in stronger and smoother welds every time.

Get High-Quality Welding Pipe Fitting Tools with H&K Fabrication

By understanding the causes of undercut, such as high welding speed, incorrect electrode angles, and excessive welding current, welders can take proactive measures to prevent this issue. However, having the right tools and equipment is also key in producing high-quality welds. At H&K Fabrication, we offer a wide range of reliable and durable welding tools specifically designed for various types of pipe welding projects. Our team of experts can also provide insights and recommendations on proper welding techniques to prevent undercutting. Shop our selection of welding tools today.