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Lamellar tearing is a welding defect that occurs in rolled steel plates that have been welded together in a way that creates shrinkage forces perpendicular to the faces of the plates and is caused mainly by sulfurous inclusions in the material. [24]
A casting defect is an undesired irregularity in a metal casting process. Some defects can be tolerated while others can be repaired, otherwise they must be eliminated. They are broken down into five main categories: gas porosity, shrinkage defects, mould material defects, pouring metal defects, and metallurgical defects.
Engineering Critical Assessment (ECA) is a procedure by which the safety of a welded structure with defects or flaws can be determined. ECAs utilize the material properties and expected stress history to determine a flaw acceptance criteria which will ensure that welds will not fail during the construction or service life of the welded structure. [1]
Most metals and alloys shrink as the material changes from a liquid state to a solid state. Therefore, if liquid material is not available to compensate for this shrinkage a shrinkage defect forms. [3] When progressive solidification dominates over directional solidification a shrinkage defect will form. [2]
800 A-scans were used to create a 2D image and 1000 images were put together to make the final 3D image. By looking at the border region between the perfect and imperfect weld, they were able to evaluate the effectiveness of OCT in finding weld defects. Air bubbles were visually apparent in the imperfectly welded region.
Weld defects such as misalignment, porosity, lack of fusion and degradation of the matrix and/or fibers may be visually apparent. Subsurface defects may not be visible, unless the composite matrix was nearly transparent and the embedded fibers did not obscure them. [6] Ultrasonic A-scan display showing a reflector in the part being tested.
In welding, equivalent carbon content (C.E) is used to understand how the different alloying elements affect hardness of the steel being welded. This is then directly related to hydrogen-induced cold cracking, which is the most common weld defect for steel, thus it is most commonly used to determine weldability.
Weld mapping is the process of assigning information to a weld repair or joint to enable easy identification of weld processes, production (welders, their qualifications, date welded), quality (visual inspection, NDT, standards and specifications) and traceability (tracking weld joints and welded castings, the origin of weld materials).