Weldability and Adhesion Testing Service

Weldability and Adhesion Testing Service – Accredited ISO/IEC 17025 Joint Integrity and Surface Bonding Assessment for the Colombian Market

Weldability and adhesion are two critical properties that determine the integrity, strength, and durability of joints and bonded assemblies in a wide range of industrial applications, including construction, oil and gas pipelines, pressure vessels, automotive manufacturing, aerospace, shipbuilding, electronics, and medical devices. Weldability evaluates the ability of a material to be joined by welding without the formation of defects such as cracks, porosity, or brittle intermetallic phases, while adhesion testing assesses the strength of bonds between coatings, adhesives, or surface treatments and their substrates. In the Colombian market, where the Superintendencia de Industria y Comercio (SIC), the Ministerio de Minas y Energía (MinMinas), the Agencia Nacional de Hidrocarburos (ANH), and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict quality and safety standards for welded structures and bonded components, the accurate evaluation of weldability and adhesion is essential for product certification, supplier qualification, quality control in manufacturing, and import-export processes. Our laboratory offers a comprehensive weldability and adhesion testing service, applying standardized methods to evaluate weld joint integrity (tensile, bend, impact, hardness, and corrosion tests) and bond strength (pull-off, shear, peel, and cross-cut tests) under controlled conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them indispensable for regulatory compliance, material validation, and market access in Colombia.

Test Samples We Regularly Examine

Our laboratory receives a wide variety of materials, welded assemblies, and bonded components for weldability and adhesion testing. Typical samples include:

• Welded plates and pipes – butt welds, fillet welds, and lap joints in carbon steel, stainless steel, aluminum, titanium, and nickel alloys.
• Weld coupons and test pieces – from welding procedure qualification (WPQ) and welder performance qualification (WPQ) tests.
• Coated and painted substrates – for adhesion testing of organic, inorganic, and metallic coatings.
• Adhesively bonded assemblies – single-lap, double-lap, and peel joints for structural adhesives.
• Composite materials and bonded joints – for aerospace, automotive, and civil engineering applications.
• Brazed and soldered joints – for electronics and heat exchanger applications.
• Prototype and new material combinations – submitted by manufacturers for validation of weldability and adhesion before series production.
• Samples retrieved from field installations – for failure analysis and assessment of joint integrity after service.

Weldability Testing – Evaluating the Integrity and Performance of Welded Joints

Weldability testing is a comprehensive evaluation of the mechanical, metallurgical, and corrosion properties of welded joints. Our procedures follow international standards and the requirements of the Colombian oil, gas, and construction sectors, ensuring that welded assemblies meet the required safety and performance criteria.

• Macroscopic and microscopic examination (ASTM E3 / ISO 17639 / NTC 6900 – metallography of welds) – a cross-section of the weld is polished, etched, and examined under a microscope to detect defects such as cracks, porosity, lack of fusion, inclusions, and undercut. We report the type, size, and location of any defects, and we classify the weld quality according to the acceptance criteria of the applicable standard (e.g., AWS D1.1, API 1104).
• Transverse tensile test (ASTM E8 / ISO 4136 / NTC 6901 – for welded plates and pipes) – a tensile specimen containing the weld is pulled to failure, and the tensile strength and the location of failure (in the weld, the heat-affected zone, or the base metal) are recorded. We report the ultimate tensile strength (in MPa) and the failure location.
• Guided bend test (ASTM E190 / ISO 5173 / NTC 6902 – for ductility and soundness) – a specimen from the weld is bent around a mandrel of specified radius and angle (e.g., 180°), and the face and root of the bend are inspected for cracks or other defects. We report the condition of the specimen (pass/fail) and any observed defects.
• Impact test (Charpy V-notch) – ASTM E23 / ISO 9016 / NTC 6903 – for weld toughness – Charpy V-notch impact specimens are machined with the notch located in the weld metal, the fusion line, and the heat-affected zone (HAZ). The impact energy (in J) is measured at the specified temperature (e.g., -20 °C, -40 °C). We report the impact energy for each location and the percentage of shear fracture.
• Hardness test (ASTM E18 / ISO 9015 / NTC 6904 – for weld and HAZ hardness) – we measure the Vickers or Rockwell hardness across the weld, the HAZ, and the base metal, and we report the hardness profile (in HV or HRC) to evaluate the extent of softening or hardening caused by the welding process.
• Corrosion test of welded joints (ASTM G36 / NTC 6905 – for stainless steel welds) – we perform a pitting corrosion test (ASTM G48) or an intergranular corrosion test (ASTM A262) on the welded joint to evaluate the susceptibility to corrosion in the weld metal and the HAZ. We report the corrosion rate, the pit density, and any intergranular attack.

Adhesion Testing of Coatings and Films – Evaluating the Bond Strength of Applied Coatings

Adhesion testing measures the strength of the bond between a coating (paint, varnish, metal plating, or thermal spray) and its substrate. This is critical for ensuring the durability and protective function of coatings in automotive, construction, and industrial applications. Our methods follow international standards and the requirements of the Colombian automotive and industrial sectors.

• Pull-off adhesion test (ASTM D4541 / ISO 4624 / NTC 6910 – for paints and coatings) – a test dolly is glued to the coated surface with a strong adhesive. After curing, a portable pull-off adhesion tester applies a tensile force perpendicular to the surface until the coating delaminates. The pull-off strength (in MPa) is recorded, and the fracture surface is inspected to determine the type of failure (adhesive, cohesive, or substrate failure). We report the pull-off strength and the fracture mode.
• Pull-off adhesion test for thermal spray coatings (ASTM C633 / NTC 6911 – for metallic and ceramic coatings) – similar to the standard pull-off test, but adapted for the higher strengths and harder materials of thermal spray coatings. We report the pull-off strength (in MPa) and the fracture mode.
• Cross-cut adhesion test (ASTM D3359 / ISO 2409 / NTC 6912 – for thin films and paints) – a lattice pattern (cross-hatch) is cut through the coating to the substrate using a multi-blade cutter. Tape is applied over the cuts and then removed, and the adhesion is rated (0B to 5B, with 5B being the best) based on the amount of coating removed. We report the adhesion rating and the classification.
• Pull-off adhesion test for soft coatings (NTC 6913 – for elastomeric and rubber coatings) – for soft coatings (e.g., rubber linings, elastomeric coatings), we perform a pull-off test using a specialized dolly and a slower loading rate to account for the viscoelastic nature of the coating. We report the pull-off strength and the fracture mode.
• Adhesion test for electroplated and electroless coatings (ASTM B571 / NTC 6914 – for metal platings) – the coating is tested by bending the substrate, sawing, or performing a burnishing test to evaluate the adhesion of the electroplated layer. We report the result (pass/fail) and any delamination.

Adhesion Testing of Adhesively Bonded Joints – Evaluating the Strength of Structural Adhesive Bonds

For adhesively bonded joints (used in aerospace, automotive, construction, and electronics), the bond strength is determined by lap shear, peel, and tensile tests. Our methods follow international standards and the requirements of the Colombian aerospace and automotive industries.

• Lap shear test (ASTM D1002 / ISO 4587 / NTC 6920 – for metal-to-metal bonding) – a single-lap joint specimen (two overlapping plates bonded with the adhesive) is pulled to failure in a universal testing machine. The lap shear strength (in MPa) is calculated from the failure load and the overlap area. We report the lap shear strength, the failure load, and the mode of failure (cohesive, adhesive, or mixed).
• Lap shear test for plastics and composites (ASTM D3163 / ISO 14673 / NTC 6921 – for plastic substrates) – similar to ASTM D1002, but adapted for plastic and composite substrates, with a slower loading rate (1.3 mm/min). We report the lap shear strength and the failure mode.
• Peel test (ASTM D1781 / ISO 11339 / NTC 6922 – for flexible adhered joints) – a flexible adhered (e.g., a thin metal foil or film) is peeled from a rigid substrate at a constant angle (e.g., 90° or 180°). The peel force (in N/mm) is measured. We report the peel strength and the failure mode.
• Floating roller peel test (ASTM D3167 / ISO 4578 / NTC 6923 – for structural adhesives) – this test is used to measure the peel resistance of a flexible bonded joint, where the flexible adherend is pulled at 90° while the rigid adherend is constrained. We report the peel strength (in N/mm).
• Fracture toughness test (Mode I – ASTM D5528 / NTC 6924 – for composite bonding) – we perform a Mode I fracture toughness test (double cantilever beam, DCB) on the bonded joint to measure the critical strain energy release rate (G_IC), which is a measure of the resistance to crack propagation. We report the G_IC (in J/m²).
• Adhesive failure mode classification (NTC 6925 – visual and SEM analysis) – after the test, the fracture surface is examined visually and with a scanning electron microscope (SEM) to classify the failure mode as adhesive (failure at the adhesive-substrate interface), cohesive (failure within the adhesive), or substrate failure. We report the failure mode and the fracture surface images.

Environmental and Aging Effects on Weldability and Adhesion – Evaluating Long-Term Durability

Weld joints and adhesive bonds can degrade over time due to thermal cycling, moisture, corrosion, and mechanical fatigue. Our environmental and aging tests simulate the service conditions of the Colombian tropical and coastal environments, and evaluate the residual strength and integrity of the joints after exposure, which is required for the certification of long-life structures and components.

• Thermal aging test (ASTM D573 / NTC 6930 – for adhesives and coatings) – the test samples (weld coupons or bonded assemblies) are aged in an oven at 70 °C for 7, 14, or 28 days, and then the mechanical properties (tensile, lap shear, pull-off) are re-measured. We report the percentage retention of the original strength and the condition of the joints.
• Humidity and water immersion test (ASTM D570 / NTC 6931 – for adhesives and coatings) – the samples are immersed in water at 40 °C for 7 days or exposed to 95 % RH at 40 °C for 7 days, and then the adhesion or weld joint strength is re-measured. We report the change in strength and any visual signs of degradation (e.g., blistering, corrosion, or delamination).
• Salt spray test (ASTM B117 / NTC 6932 – for coastal and marine applications) – the welded or bonded samples are exposed to a 5 % NaCl salt spray for 240, 500, or 1000 hours. The samples are inspected for corrosion, and the mechanical properties are re-measured. We report the corrosion level and the change in strength.
• Humidity and temperature cycling (NTC 6933 – cyclic aging) – the samples are subjected to multiple cycles of temperature and humidity (e.g., from -10 °C to +60 °C, 20 % to 90 % RH), and then the joint integrity is evaluated. We report the condition of the joints after the cycling.
• Fatigue testing of welded and bonded joints (ASTM E466 / NTC 6934 – for cyclic loading) – we perform a fatigue test (tension-tension or lap shear) on the welded or bonded samples to determine the S‑N curve and the fatigue limit. We report the number of cycles to failure and the fatigue strength.

Complementary Tests – Materials Characterization and Defect Detection

To provide a complete assessment of weldability and adhesion, we complement the mechanical tests with material characterization, microstructural analysis, and non-destructive defect detection. These analyses are essential for root-cause analysis and for improving the quality of welding and bonding processes.

• Chemical composition analysis (ASTM E415 / NTC 6940 – for metals and alloys) – we use optical emission spectroscopy (OES) or X-ray fluorescence (XRF) to determine the chemical composition of the base material and the weld filler metal, to verify the correct grade and to detect any contamination. We report the chemical composition and the compliance with the specified grade.
• Ferrite content measurement (ASTM E562 / NTC 6941 – for stainless steel welds) – we measure the ferrite number (FN) in austenitic stainless steel welds using a ferrite meter, to evaluate the resistance to hot cracking and to ensure the proper balance of ferrite in the weld. We report the ferrite number.
• Microhardness mapping (ASTM E384 / NTC 6942 – for weld and HAZ characterization) – we perform microhardness (Vickers) measurements on a grid across the weld and the HAZ to create a hardness map, which helps identify any zones of excessive hardness or softening. We report the microhardness profile.
• Non-destructive testing (NDT) – ultrasonic testing (ASTM E273 / NTC 6943) and radiographic testing (ASTM E94 / NTC 6944) – we perform UT and RT on the welded joints to detect internal defects (cracks, porosities, inclusions) that are not visible on the surface. We report the location, size, and type of any internal defects.
• Contact angle and surface energy measurement (ASTM D7490 / NTC 6945 – for adhesion prediction) – for coatings and adhesives, we measure the surface energy of the substrate using the contact angle method, which is a predictor of adhesion. We report the contact angle and the surface energy.

Test Report and Recognition in the Colombian Industrial and Construction Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (universal testing machines, impact testers, hardness testers, pull-off testers, metallographic equipment, and NDT equipment) and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the test samples (material grade, thickness, welding procedure, coating type, and bonding adhesive).
• Detailed description of the test methods applied (ASTM/ISO/NTC standards, temperature, load rate, and test conditions).
• Numerical results: tensile strength (MPa), bend test (pass/fail), impact energy (J), hardness (HV/HRC), pull-off strength (MPa), lap shear strength (MPa), peel strength (N/mm), and corrosion rate (mm/year).
• Graphical data: weld cross-section images (macro/micro), hardness profiles, and force-displacement curves.
• Comparative tables against the values specified by the client or against the limits of the NTC 6900 (Weldability), NTC 6910 (Adhesion of coatings), NTC 6920 (Adhesive joints), and the requirements of the SIC, MinMinas, ANH, and DIAN for welded and bonded components.
• Photographs and micrographs (SEM, optical) of the weld macrostructure, the fracture surfaces, and the adhesion failure zones.
• Recommendations for improving weld quality (e.g., adjusting welding parameters, preheating, or post-weld heat treatment) and for improving adhesion (e.g., surface preparation, primer application, or adhesive selection).
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Superintendencia de Industria y Comercio (SIC) for product registration and quality certification, by the Ministerio de Minas y Energía (MinMinas) and the Agencia Nacional de Hidrocarburos (ANH) for the validation of welded structures and coated components in oil, gas, and energy infrastructure, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of welded and bonded materials and components. Additionally, we offer consulting services for the development of welding procedures, the qualification of welding operators, the selection of adhesives and coatings, and the implementation of quality control programs for weldability and adhesion, contributing to the safety, reliability, and longevity of industrial products and structures in the diverse and growing Colombian market.