Everything You Need to Know about Guided Bend Testing of Welds
Two important reasons to test the ductility of a welded joint; product manufacturing that requires welding for assembly and when evaluating a welder's ability. Before product manufacturing commences,, the designed welding process must be tested to ensure the weld produced possesses adequate ductility. Also assessing a welder's competence to perform a sound weld can be determined by testing the ductility of a weld created.
Guided bend testing is a critical part of the weld qualification process. It evaluates the strength, ductility, and soundness of a weld by bending the welded specimen to a specified angle. Whether you're a seasoned welder or preparing for your first qualification test, understanding bend testing, how to prepare, and how to pass them is essential. In this article, we’ll dive into the details of bend testing, including the role of specialized equipment like the Hydraulic Wrap-Around Bender from Triangle Engineering.
What is a Guided Bend Test of a Weld?
A guided bend test is a type of destructive testing in welding used to assess the quality of a weld. ASTM E190 describes requirements for guided bend testing of welded materials. It involves bending a welded specimen to determine if the weld and heat-affected zone (HAZ) can withstand stress without cracking or failing. Internal defects not presented by X rays, may become visible in a specimen subjected to bend stressing. Bend tests are commonly required for welding qualification tests and are used to ensure welds meet industry standards, such as those set by the American Welding Society (AWS) and American Society of Mechanical Engineers (ASME).
There are three main types of bend tests:
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Face Bend Test: The weld face is placed on the tension side of the bend.
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Root Bend Test: The weld root is placed on the tension side of the bend.
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Side Bend Test: The weld cross section is placed on the tension side of the bend.
All three tests evaluate the weld’s integrity, but they focus on different areas of the weld joint.
How Does Guided Bend Testing Work?
There are two main types of guided bend test fixtures recognized by welding code; plunger and wraparound style. The wraparound method is recognized as the preferred method of bend testing aluminum weldments by the American Welding Society (AWS). Bend testing involves placing a welded specimen into a bend test fixture, which applies force to bend the specimen around a die of a specific radius. The goal is to bend the specimen to a predetermined angle (usually 180 degrees) without causing cracks or defects in the weld.
The Role of the Bending Machine
The bending machine, such as the Hydraulic Wrap-Around Bender from Triangle Engineering, is designed to apply consistent and controlled force to the specimen. This machine ensures accurate and repeatable results, making it a valuable tool for weld qualification testing.
The process typically involves:
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Preparing the Specimen: The welded sample is cut and ground to the required dimensions.
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Loading the Specimen: The specimen is placed into the bending machine.
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Applying Force: The machine bends the specimen around a die.
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Inspecting the Results: After bending, the specimen is examined for cracks or defects.
How to Prepare for a Bend Test
Preparation is key to passing a bend test. Here’s what you need to do:
1. Understand the Welding Procedure Specification (WPS)
The welding procedure specification (WPS) outlines the parameters for the weld, including material type, joint design, and welding technique. Familiarize yourself with these details to ensure your weld meets the required standards.
2. Practice Proper Welding Techniques
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Maintain Consistent Travel Speed: Inconsistent speed can lead to defects like lack of fusion or excessive penetration.
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Control Heat Input: Too much heat can weaken the heat affected zone (HAZ) , while too little can cause incomplete fusion.
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Ensure Proper Electrode Angle: Incorrect angles can result in slag inclusion or undercutting.
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Clean the Weld: Remove any slag, spatter, or contaminants that could affect the test results.
3. Prepare the Specimen Correctly
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Cut and Grind the Specimen: Use a saw or grinder to remove bend test specimens from the welded test assembly. Ensure the edges are smooth and free from burrs. Removal and preparation of bend test specimens can be achieved quickly and accurately utilizing Triangle Engineering’s Weld Coupon Abrasive Cutter and Back Strap Removal Tool
How to Pass a Bend Test
Passing a bend test requires attention to detail and adherence to best practices. Here are some tips to help you succeed:
1. Avoid Common Welding Defects
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Porosity: Caused by trapped gas in the weld. Prevent this by using clean materials and proper shielding gas.
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Lack of Fusion: Ensure proper heat input and electrode angle.
2. Ensure Proper Fit-Up and Alignment
Misaligned joints or improper root gaps can lead to test failure. Double-check your setup before welding in accordance with the weld procedure specification (WPS)
3. Follow the WPS
Deviating from the welding procedure specification (WPS) can result in bend test failure. Pay close attention to parameters like voltage, amperage, and travel speed.
4. Inspect Your Weld Before Testing
Perform a visual inspection to identify any obvious defects. Address any issues before submitting the specimen for testing.
The Role of the Hydraulic Wrap-Around Bender
The Hydraulic Wrap-Around Bender from Triangle Engineering is a state-of-the-art weld bend testing machine designed for precise and efficient bend testing. Its hydraulic system ensures consistent force application, while its wrap-around design minimizes specimen distortion. This machine is ideal for weld qualification testing and welder training purposes.
Key Features:
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Hydraulic Operation: Provides smooth and controlled bending force.
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Wrap-Around Design: Reduces stress on the specimen for more accurate results.
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Simple Tooling: Change between bending radii quickly and with minimal effort.
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Durable Construction: Built to withstand heavy use in industrial environments.
For more information, check out the Hydraulic Wrap-Around Bender on Triangle Engineering’s website.
Conclusion
Bend testing is a critical step in PQR development, welder training and performance qualification testing . By understanding how the process works, preparing thoroughly, and using the right equipment, you can increase your chances of passing the test and advancing your welding career.
If you’re looking for reliable bending equipment, consider the Hydraulic Wrap-Around Bender from Triangle Engineering. Its precision and durability make it an excellent choice for any facility performing welder training and qualification testing.