Metal product form Types of discontinuities Castings Porosity, gas, and microshrinkage Segrega Cold shuts Plate and sheet Edge cracking Lamination Extrusions and drawn products Edge cracking More detailed descriptions, with physical characteristics and mechanisms for the creation of these defects, are contained in subsequent sections of this Volume. Problems that may develop during subsequent processing, such as heat treating and welding are discussed in the section "Manufacturing/Installation Defects" in this article These material defects can be generally described as discontinuities that degrade the performance of a product in some way. Despite measures taken to control, document, measure, analyze, and improve the processes involved in manufacturing the metal product(such as in TQM and Six Sigma systems), material defects occur. Many defective products are prevented from leaving the mill, foundry, or forge through diligence in adhering to internal procedures and uality-assurance systems. Yet defective materials are sometimes delivered Depending on the criticality, periodic field inspection may be required and may reveal defects not previously identified. A case study of one such occurrence lustrates the effectiveness of a maintenance plan that includes periodic inspection chair lift grip mechs Laps in Ski Chair Lift Grip Components. Alloy steel forgings used as structural members of a ski Example 3: Forg hanism identified to have contained forging laps during an annual magnetic particle inspection of all chair lift grip structural members at a mountain resort. A lap in one of the lift grip components(Fig. 15)measured 4.8 mm( in )long on the surface. An example of the metallurgical cross section through a similar la ap is provided in Fi Ig. 16. In accordance with the AsTM standard for magnetic particle inspection, the paint on the forgings was stripped prior to performing the magnetic particle inspection, since the thickness of the paint slightly exceeded the maximum allowable 0.05 mm(0.002 in )thick paint layer. It should be noted that prior annual inspections, performed at a contracted magnetic particle inspection facility, revealed no significant indications on these forgings. However, the paint was not stripped prior to the magnetic particle inspection at that timeMetal product form Types of discontinuities Cavity shrinkage Centerline pipe Parting line grain flow Inclusions Castings Porosity, gas, and microshrinkage Cavity shrinkage Segregation Cold shuts Inclusions Plate and sheet Edge cracking Laminations Flakes Extrusions and drawn products Edge cracking Seams Steps Central bursts More detailed descriptions, with physical characteristics and mechanisms for the creation of these defects, are contained in subsequent sections of this Volume. Problems that may develop during subsequent processing, such as heat treating and welding, are discussed in the section “Manufacturing/Installation Defects” in this article. These material defects can be generally described as discontinuities that degrade the performance of a product in some way. Despite measures taken to control, document, measure, analyze, and improve the processes involved in manufacturing the metal product (such as in TQM and Six Sigma systems), material defects occur. Many defective products are prevented from leaving the mill, foundry, or forge through diligence in adhering to internal procedures and quality-assurance systems. Yet defective materials are sometimes delivered. Depending on the criticality, periodic field inspection may be required and may reveal defects not previously identified. A case study of one such occurrence illustrates the effectiveness of a maintenance plan that includes periodic inspection. Example 3: Forging Laps in Ski Chair Lift Grip Components. Alloy steel forgings used as structural members of a ski chair lift grip mechanism were identified to have contained forging laps during an annual magnetic particle inspection of all chair lift grip structural members at a mountain resort. A lap in one of the lift grip components (Fig. 15) measured 4.8 mm ( 3 16 in.) long on the surface. An example of the metallurgical cross section through a similar lap is provided in Fig. 16. In accordance with the ASTM standard for magnetic particle inspection, the paint on the forgings was stripped prior to performing the magnetic particle inspection, since the thickness of the paint slightly exceeded the maximum allowable 0.05 mm (0.002 in.) thick paint layer. It should be noted that prior annual inspections, performed at a contracted magnetic particle inspection facility, revealed no significant indications on these forgings. However, the paint was not stripped prior to the magnetic particle inspection at that time