Fig. 15 Forging lap on ski lift fixed jaw Fig. 16 Microstructure of forging lap in another ski lift grip component. As-polished 111 The presence of the laps, which are rejectable according to the manufacturer's drawings, indicates the forgings were delivered from the manufacturer in this condition. Aside from the obvious procedural roots related to the quality system of the manufacturer, the present issue was whether or not the laps (i.e., sharp-notched discontinuities) had"grown"in progressive manner, such as by fatigue or stress-corrosion cracking, during the five years that the components had been The material was confirmed to be 34CrNiMo6(a European Cr-Ni-Mo alloy steel containing 0. 34%C), as required. The broken-open lap(Fig. 17)revealed a darkened area on the fracture surface that was consistent with the dimensions of the lap. The darkened area extended 0.89 mm(0.035 in )deep. Adjacent to the darkened area, a small area of bright, fibrous fracture features was observed, as well as a transition to a bright, faceted fracture appearance. Scanning electron microscope examination in conjunction with energy-dispersive x-ray spectroscopy(EDS)revealed a heavy oxide on the dark area of the fracture surface(Fig. 18). The bright area adjacent to the dark area contained ductile dimple rupture, which changed to cleavage fracture beyond this area. It was determined through stereomicroscopy, fractography, and metallography that the oxidized portion of the fracture was the preexisting forging lap and that both bright fracture areas were created in the laboratory during the breaking-open process. a cross-sectional view of the broken-open lap is shown Fig. 19, depicting the field of oxides in the material beneath the lap surface Thefileisdownloadedfromwww.bzfxw.comFig. 15 Forging lap on ski lift fixed jaw Fig. 16 Microstructure of forging lap in another ski lift grip component. As-polished. 111× The presence of the laps, which are rejectable according to the manufacturer's drawings, indicates the forgings were delivered from the manufacturer in this condition. Aside from the obvious procedural roots related to the quality system of the manufacturer, the present issue was whether or not the laps (i.e., sharp-notched discontinuities) had “grown” in a progressive manner, such as by fatigue or stress-corrosion cracking, during the five years that the components had been in service. The material was confirmed to be 34CrNiMo6 (a European Cr-Ni-Mo alloy steel containing 0.34% C), as required. The broken-open lap (Fig. 17) revealed a darkened area on the fracture surface that was consistent with the dimensions of the lap. The darkened area extended 0.89 mm (0.035 in.) deep. Adjacent to the darkened area, a small area of bright, fibrous fracture features was observed, as well as a transition to a bright, faceted fracture appearance. Scanning electron microscope examination in conjunction with energy-dispersive x-ray spectroscopy (EDS) revealed a heavy oxide on the dark area of the fracture surface (Fig. 18). The bright area adjacent to the dark area contained ductile dimple rupture, which changed to cleavage fracture beyond this area. It was determined through stereomicroscopy, fractography, and metallography that the oxidized portion of the fracture was the preexisting forging lap and that both bright fracture areas were created in the laboratory during the breaking-open process. A cross-sectional view of the broken-open lap is shown in Fig. 19, depicting the field of oxides in the material beneath the lap surface. The file is downloaded from www.bzfxw.com