If you are training for a career as a welder or are looking into enrolling in a welding school or welding trade school, one of the most important things you can do is familiarize yourself with the common challenges that you might encounter in your line of work.
A welder’s most common obstacle to overcome is a welding defect. Defects in a weld are flaws that affect its structural integrity, appearance or performance.
In this article, we will go over what welding defects are and discuss 16 common welding defects and how training at a welding trade school like the one offered at Universal Technical Institute (UTI) can help you learn the skills necessary to avoid these.
What Is a Welding Defect?
A welding defect is a discontinuity or imperfection in a weld that degrades the weld's overall quality. Welding defects can compromise the strength, durability or appearance of a welded joint. They can result from a variety of factors, such as improper welding techniques, incorrect settings on equipment, or external influences like contamination or material defects.
Knowledge of welding defects and ways to avoid them is an important part of professional welding education, which is why welding schools spend so much time on technique, inspection and quality control.
Universal Technical Institute’s Welding Technology program focuses on providing hands-on training in various arc welding methods, enabling students to learn how to prevent welding defects. Students start off learning the principles of welding and move through a range of courses that build their skills from the ground up.
16 Common Welding Defect Types
Whether you’re working with MIG, TIG or stick welding, defects can happen. Here are 16 common types every aspiring welder should know:
Distortion
When welded metal starts to warp or change shape, it's called distortion. Poor clamping, uneven heating or improper sequencing are common culprits.
Excess reinforcement
This happens when too much filler metal is added to the joint, resulting in an overly thick bead. It can weaken the weld and make finishing more difficult.
Hot tear
Also known as hot cracking, this defect occurs when the weld contracts unevenly as it cools, causing fractures in the weld metal.
Slag inclusion
Slag inclusion is a defect that can occur when nonmetallic materials get trapped in the weld. Some causes can be improper cleaning or incorrect welding techniques.
Spatter
Spatter refers to tiny droplets of molten material that stick to the surrounding surface. It’s often caused by incorrect voltage, current or travel speed.
Undercut
This defect appears as a groove along the edge of the weld bead. It can weaken the joint and typically results from using excessive heat or improper technique.
Weld crack
Welding cracks can form during or after welding and are one of the most serious defects. They’re usually caused by thermal stress, contamination or poor joint design.
Whiskers
Whiskers are thin projections of metal that extend from the weld surface. They’re often the result of excessive current or improper torch angles.
Burn through
When too much heat is applied, the weld pool can melt entirely through the base material, creating holes or openings.
Incomplete fusion
Incomplete fusion occurs when the weld metal fails to properly bond with the base metal or adjacent weld beads, often due to insufficient heat or incorrect technique.
Incomplete penetration
Incomplete penetration happens when the weld doesn’t extend through the entire thickness of the joint, leaving weak spots behind.
Lamellar tearing
Lamellar tearing is caused by stresses acting on the material’s thickness, leading to cracks that run parallel to the surface. It’s more common in materials with poor ductility.
Mechanical damage
Mechanical damage includes any external harm to the weld, such as dents or scratches, usually caused by improper handling or post-weld processing.
Misalignment
When two pieces of metal aren’t properly aligned before welding, the resulting joint can be structurally weak and visually unappealing.
Overlap
When the weld metal flows over the base metal without fusing properly, overlap can occur. It often results from improper travel speed or torch angles.
Porosity/blowholes
Porosity refers to small gas pockets trapped within the weld, while blowholes are larger voids. Both are caused by gas contamination or improper shielding.
Prep To Forge a Welding Career With UTI
Learning to identify and prevent welding defects is a skill that comes with proper training and hands-on practice. UTI’s welding trade school program can teach you about welding defects and a range of other topics, preparing you to pursue a career in the industry after graduating.1
Interested in becoming a welder? It’s easy to get started. Enroll in our Welding program today and graduate in just 9-10 months!
Universal Technical Institute of Illinois, Inc. is approved by the Division of Private Business and Vocational Schools of the Illinois Board of Higher Education.