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machining defects

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Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001601
EISBN: 978-1-62708-235-8
... This paper describes an investigation of the cause of defects and failures during flow forming of thin wall high strength tubes from AISI 4130 steel. The investigation includes study of the various metallurgical and/or machine parameters likely to cause these problems. The common defects reported for...
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001785
EISBN: 978-1-62708-241-9
... Failed jaw of wrench shown next to an un-failed wrench The maintenance facility used 3/4-inch (19 mm) wrenches produced by a single manufacturer which were removed from tool boxes and store stock. The nonfailed wrench population was visually inspected for any obvious defects and none were found...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c0046182
EISBN: 978-1-62708-218-1
... Abstract A connecting cap from a truck engine fractured after 65,200 km (40,500 mi) of normal service. The cap was made from a 15B41 steel forging and was hardened to 29 to 35 HRC. Visual examination of the fracture surface disclosed an open forging defect across one of the outer corners of the...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048102
EISBN: 978-1-62708-224-2
... the web surface. Fatigue cracking of the wheel was initiated at forging defects in the web. Replacement wheels were machined all over and were magnetic particle inspected to detect any cracks that could act as stress raisers. Cracks Defects Magnetic particle testing 1055 UNS G10550 Fatigue...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c0047161
EISBN: 978-1-62708-235-8
... Abstract Routine magnetic-particle inspection revealed crack indications in a number of shafts produced from hot-rolled 4130 steel bar. A pronounced indication of this size is cause for rejection if the defect is not eliminated during subsequent machining. A microstructural analysis of the...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.rail.c9001418
EISBN: 978-1-62708-231-0
... inherent defect in the form of a slag inclusion or crack situated at the surface. That the crack only showed itself after a period of service suggests that initially it may have been slightly below the surface of the machined pin and some slight extension outwards took place in service. This discontinuity...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001260
EISBN: 978-1-62708-235-8
... depth of the material having been removed in machining or in centreless grinding. The observations of the magnetic crack detection test were confirmed by deep etch test in 10% hydrochloric acid. Metallographic examination of transverse sections through the defective areas showed decarburisation to...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.conag.c9001432
EISBN: 978-1-62708-221-1
... Abstract During the pre-test inspection following the stress calculation check on a 7-ton capacity Scotch derrick crane, it was noted that threads on the back stay anchorage bolts were of unusually fine pitch (11 tpi) and that the machined faces of the nuts showed irregular pits or depressions...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001541
EISBN: 978-1-62708-235-8
.... Fluorescent penetrant inspection showed that the crack ran above and below the hole out onto the machined flat surface of the flange. Fig. 1 Examination by electron microscope proved the crack to be a forging defect called a cold shut—the photo (reproduced here at 38% reduction) demonstrates its...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001217
EISBN: 978-1-62708-235-8
... temperature is too high. In order to avoid this defect in the future the sole recommendation to be made is to accelerate the cooling rate through the critical region between 1200 to 900° C to such an extent as is practicable with respect to machinability. Reference 1. Naumann F. K. , Hengler...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.marine.c9001511
EISBN: 978-1-62708-227-3
... Abstract An LNG tanker experienced a fracture of the solid tail shaft, which is a section of the main drive shaft. The tail shaft was made of a forged low-carbon steel. In spite of two ultrasonic inspections, a large defect the size of a football in the center of the shaft was missed. During...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.aero.c9001216
EISBN: 978-1-62708-217-4
... metallographically. The metallographic assessment of dimple defects will be described in the following. The specimens are made of clad aluminium sheet of alloy type Al Zn Mg Cu 1.5. Figure 1 is a schematic representation of the mode of operation of a dimpling machine and Fig. 2 a perfect dimple in aluminium...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c0046210
EISBN: 978-1-62708-235-8
... the stresses will not be this high. However, if it is feasible to machine the critical oil hole so that the defects are smaller than those that will propagate at this stress, then such an operation is clearly indicated, because any fatigue crack propagation problem could certainly be eliminated. In...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.auto.c9001256
EISBN: 978-1-62708-218-1
... to be cracks were first noticed in visual inspection after rough machining of the hardened and tempered forgings. Magnaflux test confirmed the defects but did not dispel the doubt as to whether the affected areas were open cracks or non-metallic inclusions. The defects were not in one continuous line...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.mech.c9001158
EISBN: 978-1-62708-225-9
... defects and was of high purity, although a number of minor surface defects such as rolling laps were found. The spring was heat treated and its surface strengthened by shot-peening, but the surface was also decarburized to a depth of approximately 0.03 mm which resulted in a lowering of the surface...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.mech.c0046057
EISBN: 978-1-62708-225-9
... micrographic examination showed a microstructure of tempered martensite with low inclusion content as well as a pit or burned spot on the outer area of the ring. The defect was approximately 0.18 mm (0.007 in.) deep and 0.5 mm (0.020 in.) in diam and had a hardness of 58 to 60 HRC. The base metal adjacent to...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.machtools.c9001154
EISBN: 978-1-62708-223-5
... be recognized as flaky cracks already in the fracture, and which later were united. No material defects could be detected in the cross section parallel to the fracture plane except for these very short cracks. These comparatively insignificant defects were sufficient to cause the fracture during high...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.usage.c9001430
EISBN: 978-1-62708-236-5
... torsional fatigue. A second shaft carried as spare gear was fitted and failure took place in a similar manner in about the same period of time. Examination revealed that the tapered portion of the Fe-0.6C carbon steel shaft had been built up by welding prior to final machining. A detailed check by the...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c9001426
EISBN: 978-1-62708-224-2
... service provided that the welds are free from serious defects, and this can only be ensured by careful initial setting of the machine and frequent checking of this, coupled with an inspection and testing procedure that is effective in preventing any defective chain going into service. Selected...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.usage.c9001230
EISBN: 978-1-62708-236-5
... comparatively short journal pins at high stresses. This crankshaft fracture was an example of the damage that is caused or promoted neither by material nor heat treatment mistakes nor by defects of design or machining, but solely by overstressing. Crankshafts Induction hardening Torsional fatigue...