Four-Point Bending Test Service for Weldments for Global Welding Qualification
As an ISO/IEC 17025 accredited laboratory, we deliver a specialized four-point bending test service for weldments that verifies the ductility, fusion quality, and structural soundness of welded joints. Our four-point bending test service for weldments supports fabricators, manufacturers, and exporters who must demonstrate conformity to ISO 5173, ISO 4136, AWS D1.1, ASME BPVC Section IX, and regional welding procedure qualification standards across the European Union, North America, the Middle East, and Asia. Every test is performed under our CNAS-accredited quality system, producing reports accepted by notified bodies, third-party inspectors, and procurement authorities worldwide.
Product Samples We Regularly Test in Our Four-Point Bending Test Service for Weldments
- Butt-welded steel plates and sheets — for structural steel, pressure vessels, shipbuilding, and pipeline projects
- Welded pipe and tube joints — circumferential and longitudinal welds for oil and gas, power generation, and process piping
- Dissimilar metal weldments — for transition joints, cladding, and repair welds requiring special bend evaluation
- Aluminum and aluminum alloy welded joints — for aerospace, automotive, and marine structure qualification
- Stainless steel and nickel alloy weldments — for chemical, pharmaceutical, and high-temperature service
- Fillet weld and T-joint specimens — for supplementary bend testing of welded connections under structural codes
- Weld overlay and cladding bend specimens — for corrosion-resistant and wear-resistant surface qualifications
Four-Point Bending Test Methods for Weldment Evaluation
- Transverse face bend test per ISO 5173 and ASME BPVC Section IX — the weldment specimen is placed with the weld face in tension and bent around a defined former using a four-point loading arrangement, revealing surface-breaking discontinuities such as lack of fusion, porosity, cracks, and incomplete penetration in the weld face area.
- Transverse root bend test per ISO 5173 and ASME BPVC Section IX — the specimen is oriented with the weld root in tension and bent to a specified angle, evaluating the soundness of the root pass and the fusion at the weld edges, critical for single-sided and field welds.
- Side bend test for thick weldments per ISO 5173 and ASME BPVC Section IX — for weldments with thickness greater than approximately 10 mm, full-thickness side bend specimens are prepared and bent so that the entire weld cross-section is subjected to tensile strain, providing the most comprehensive assessment of weld soundness across the joint.
- Longitudinal bend test for anisotropic or high-strength weld metals per ISO 5173 — when specified for materials with directional properties or for high-strength steel weld metals, longitudinal specimens are bent to evaluate the ductility and soundness of the weld metal along its length.
- Four-point bend testing for weld procedure qualification per ISO 15614-1 and AWS D1.1 — the bend tests are performed as part of the complete welding procedure qualification record, demonstrating that the proposed welding parameters produce a joint with adequate ductility and freedom from harmful defects.
- Bend testing after post-weld heat treatment per ASME BPVC Section IX — the weldment is subjected to the specified heat treatment cycle and then bend tested to verify that the heat treatment has not reduced ductility or introduced defects such as stress-relief cracking.
Specimen Preparation and Test Parameters for Four-Point Bending of Weldments
- Specimen dimensions and surface preparation per ISO 5173 and ASTM E190 — the weldment specimens are machined to the specified width, thickness, and length, with the weld reinforcement removed flush and the edges rounded to prevent premature crack initiation at non-weld locations.
- Bend former diameter and bend angle selection per the applicable welding code — the former diameter is selected based on the material type, thickness, and elongation requirements, typically ranging from 2t to 4t where t is the specimen thickness, and the bend angle is typically 180 degrees for full qualification.
- Four-point loading configuration per ISO 5173 — the specimen is supported at two outer points and loaded at two inner points, producing a constant bending moment region between the inner loading points that subjects the weld and heat-affected zone to uniform maximum tensile strain.
- Test temperature and environmental conditions per the welding procedure specification — bend testing is normally performed at ambient temperature, but may be conducted at elevated or sub-zero temperatures when required by the application or the material standard.
- Loading rate control per ISO 6892-1 and customer specifications — the bending force is applied at a controlled rate to avoid dynamic effects, and the maximum load and any load drops during the test are recorded for subsequent evaluation.
- Post-test visual and microscopic examination — the bent specimens are inspected for cracks, open defects, and other discontinuities, with the size and location of any indications recorded against the acceptance criteria of the applicable welding code.
Acceptance Criteria and Evaluation for Four-Point Bend Test Service for Weldments
- Evaluation of surface discontinuities per ISO 5173 and AWS D1.1 — any crack or open defect exceeding 3 mm in length, or any evidence of lack of fusion, lack of penetration, or porosity visible on the convex surface of the bent specimen, is cause for rejection, with the exact limit defined by the governing specification.
- Assessment of weld soundness and fusion quality — the bend test reveals whether the weld metal, heat-affected zone, and base material have fused properly and whether the joint possesses the required ductility to undergo plastic deformation without cracking.
- Correlation with tensile and impact test results — four-point bend test results are correlated with transverse tensile and Charpy impact data from the same weldment to provide a complete picture of the joint's mechanical performance and its suitability for the intended service.
- Reporting of test parameters and results per ISO/IEC 17025 — the test report includes the specimen identification, welding parameters, bend former diameter, bend angle, test temperature, and the detailed evaluation of any discontinuities, along with the acceptance decision.
- Weld procedure qualification and welder performance certification — successful four-point bend tests are an essential part of welding procedure qualification records and welder performance qualification, demonstrating that the welding process and the welder can consistently produce sound joints.
Report Recognition and ISO/IEC 17025 Compliance
Every test method described in this four-point bending test service for weldments is covered by our ISO/IEC 17025 scope of accreditation. Our technical reports and bend test certificates are accepted by European notified bodies for welding procedure qualification, by North American code authorities referencing ASME and AWS standards, and by customs and procurement agencies across the Middle East, Australia, and Asia. Whether you require a complete welding procedure qualification test package, a batch release bend test for a production weld, or a root cause failure analysis of a weld defect, our laboratory provides the measurement accuracy and welding engineering expertise that the global fabrication and construction industries demand.
