What is a Weld Coupon?

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A weld test coupon is a small piece of metal used to test a welder’s proficiency in various welding procedures. Weld coupons are commonly utilized for applications such as welder qualifications, training, practicing difficult joints, and more. Here, we will dive into the specifics of weld coupons and their different applications, as well as the purpose of welder qualification tests.

What Is a Weld Coupon?

Welding is critical to various industrial tasks; therefore, it’s important for welders to demonstrate their proficiency to ensure they can deliver quality results. Many welding certifications require welders to showcase their skill level by passing a welding coupon test according to the required standards and codes.

Welding coupons are small pieces of metal, typically in plate or pipe form, used to evaluate a welder’s skill through destructive testing, visual inspection, and other methods. This allows welding professionals to demonstrate and determine another welder’s ability to deposit a high-quality weld joint.

Other Applications of Weld Coupons

Weld coupon testing is ideal for various applications, including:

• Welder Qualification/Certification. Weld coupons can be used for welding qualification tests, which determine whether a person or machine can produce a quality weld that is up to code.
• Welder Training. Weld coupons can be used to demonstrate proper welding techniques and assess a trainee’s skills.
• Welding Procedure Qualification. Welders must be able to meet specific inspection criteria to become qualified for certain welding procedures. Weld test coupons can be used for this qualification process.
• Mock Fit-up/Practice Joints. Professional welders and trainees can use weld coupons to develop mock-ups and practice complex joints.
• Procedure Qualification Record (PQR) Materials. A PQR documents what happened during weld coupon testing as well as the result of the test.
• Electron Beam Welding. Electron-beam welding is a fusion welding process in which a beam of high-velocity electrons is applied to two materials to be joined.
• Laser Beam Welding. Laser beam welding (LBW) is a welding technique used to join pieces of metal or thermoplastics through the use of a laser.

What Is the Welder Qualification Test?

A welding qualification test is a hands-on skills test conducted by a certified welding inspector to determine the quality of a welder or machine’s welds based on the code or procedure required by the industry standard, job site, or company. Specifically, a welding qualification test demonstrates a welder’s ability to deposit a quality weld when following a qualified welding procedure. As such, welders are typically provided with a Welding Procedure Specification (WPS) to follow while performing the test.

If a welder can demonstrate their ability to perform a weld that requires a high skill level, they will be deemed competent to perform welding procedures that are easier than what was demonstrated during the qualification test.

Welder qualification tests can take various forms. The reasons for this include:

• Each welding process requires different skill sets to perform.
• Different materials present their own difficulties or issues when welding and therefore require different skills.
• Different-sized workpieces require specific skills to account for varying diameters and thicknesses.
• Welding different-shaped materials, like plates and pipes, require different skills.
• Each welding code has its own unique requirements.

Weld Coupons From AAA Metals

Welding coupons play a critical role in evaluating a person or machine’s ability to accurately carry out certain welding procedures and create high-quality joints. At AAA Metals, we can manufacture weld test coupons in high quantities for use in various applications, including qualification tests, recalibrating robotic welders, training/practice, and more. Using grinders, we can create weld coupons with specific angles that can be used to practice and perform welding tests at difficult angles.

For more information about our weld coupon capabilities, contact AAA Metals or request a quote today. You can learn more by browsing our precision waterjet cutting, precision sawing, and precision laser cutting services.

Coupons can be furnished with a variety of finishes depending on your particular application. Some of the typical finishing processes are explained below.

Mill Finish – Coupon surfaces are provided in the as-received condition (as the material was received from the mill). After the coupons have been cut to size, no additional finishing is performed to improve the surface or to remove imperfections.  This finish is typically used to simulate a “worst-case” condition.  Coupons with a mill finish may have scratches, corrosion, and other defects upon receipt. It is important to note that Metal Samples provides mill-finish coupons as-is and accepts no responsibility for the condition of the surface.

    Glass Beaded – Coupon surfaces are blasted with fine glass beads to remove mill scale. This typically results in a finely textured surface with a typical surface roughness of approximately 50 µIn RA on steel coupons*.  Glass beading should remove any mill scale and surface corrosion, but it may not remove all surface defects such as scratches.  While not perfect, glass beaded coupons have a much better surface compared to a mill finish and provide more consistent surfaces.  The glass beaded surface finish is very economical and is our most popular surface finish.     Coarse Grit Blasted – Coupon surfaces are grit blasted using a coarse media such as aluminum oxide to remove mill scale. This also results in a textured surface, but it is coarser than a glass beaded surface.  Typical surface roughness will be 65-70 µIn RA on steel coupons*. Coarse grit blasting also removes mill scale and surface corrosion and does a better job of removing surface defects such as scratches compared to glass beading.     Sanded – Coupons are finished using a directional sanding process.  A wide range of surface roughness can be achieved by using different grit sizes.  A 120 grit belt is standard and is commonly used in corrosion tests. This results in a typical surface roughness of 125-130 µIn RA on steel coupons*. If a smoother surface finish is desired, finer belts such as 400 grit and 600 grit can be used.  Sanded coupons will exhibit a linearly directional finish and may exhibit slight beveling along the edges.     Double Disc Ground – Coupons are finished between two counter-rotating grinding stones, resulting in an extra-fine finish. This process is more expensive, but results in a superior, more repeatable surface finish compared to the other methods.  Double Disc Ground coupons will exhibit swirled grinding marks on the faces and have a typical surface roughness of 35-40 µIn RA on steel coupons*.  Finished surfaces should be free of contaminants and defects.  This option is excellent for studies where surface finish or repeatability is critical.     Lapped – Coupons are machine finished on a lapping plate using a lapping compound to produce a very flat and smooth surface.  Lapping can achieve surface roughness as low as 3-5 µIn RA on carbon steel*.  This method produces one of the best surface finishes but is more expensive than other methods, including grinding.     * Surface roughness listed is for reference purposes only.  Actual surface roughness will vary depending on the material and condition.

A note on surface finish
It is important to note that the items described above are finishing processes and not actual surface finishes. A true surface finish callout will specify the required surface roughness in a measurable unit such as RA or RMS. If coupons are ordered by a finishing process such as “120-grit sanded” then Metal Samples provides coupons finished using that process, but the actual surface roughness is not controlled.  Coupons can be ordered with a specific surface roughness if that is required, in which case Metal Samples will select the appropriate method(s) to achieve the desired roughness.