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During laser welding, air bubbles can form and cause a degradation in the mechanical properties of the joint. Current inspection techniques are limited to finding air bubbles on the surface of the weld (optical and scanning electron microscopy). Destructive testing is usually required to find volumetric flaws.
The main part of the welder's test consists of welding one or more test coupons which are then examined using non-destructive and destructive methods. The extent of certification is described by a number of variables, which include the specific welding process, type of deposited metal, thickness, joint design, position, backing, and others.
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).
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]
The American Society of Mechanical Engineers (ASME) similarly defines a WPS as a written document that provides direction to the welder or welding operator for making production welds in accordance with Code requirements. [2] ASME also defines welding PQR as a record of variables recorded during the welding of the test coupon. The record also ...
In the case of high stress or safety critical welds, weld monitoring will be employed to confirm the specified welding parameters (arc current, arc voltage, travel speed, heat input etc.) are being adhered to those stated in the welding procedure. This verifies the weld as correct to procedure prior to nondestructive evaluation and metallurgy ...
For example, the factor of welding position influences weld quality, that welding codes & specifications may require testing—both welding procedures and welders—using specified welding positions: 1G (flat), 2G (horizontal), 3G (vertical), 4G (overhead), 5G (horizontal fixed pipe), or 6G (inclined fixed pipe). To test the quality of a weld ...
The weld structure can be examined by optical microscopy [3] [4] [5] and scanning electron microscopy. [ 6 ] [ 4 ] [ 5 ] [ 3 ] The computer finite element method (FEM) is used to predict the shape of the flash and interface and others, not only for rotary friction welding (RFW), [ 7 ] but also for friction stir welding (FSW), [ 8 ] [ 9 ] linear ...