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Acicular structure

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Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048060
EISBN: 978-1-62708-224-2
... and rough machining and chatter marks were evident on the threads. Beach marks that emanated from the thread-root locations on opposite sides of the fracture surface identified these locations to be the origins of the fracture. A medium-coarse slightly acicular structure was revealed by metallographic...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048068
EISBN: 978-1-62708-224-2
... where cracking started was revealed by visual examination of the fracture region. Almost 50% of the fracture surface was found to contain beach marks (indicative of fatigue failure) while the remainder contained cleavage facets. A medium-coarse acicular as-forged structure was revealed by metallographic...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048068
EISBN: 978-1-62708-224-2
... where cracking started was revealed by visual examination of the fracture region. Almost 50% of the fracture surface was found to contain beach marks (indicative of fatigue failure) while the remainder contained cleavage facets. A medium-coarse acicular as-forged structure was revealed by metallographic...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.machtools.c9001250
EISBN: 978-1-62708-223-5
... with 2% nital). 200 × Figure 4 illustrates the structure of a longitudinal microsection through the fracture surface in the vicinity of the cross. The structure on the left side of the picture is finely acicular and was strongly attacked by the etching reagent. Adjacent to this and extending...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c9001262
EISBN: 978-1-62708-224-2
... along the austenitic grain boundaries. Such fractures are characteristic results of strong overheating. The coarse-grained, coarse acicular heat-treated structure of the chain link confirmed overheating. Because temperatures in excess of 1150 deg C are required for the solution of impurities, it is more...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001214
EISBN: 978-1-62708-235-8
... had the quench structure of low-carbon steel, the structure of the flattened area consisted of coarse acicular martensite with a small amount of pearlite (quench troostite) and ferrite. Therefore the sleeve was overheated and probably quenched directly from case. To prevent damage, it would have been...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c9001209
EISBN: 978-1-62708-224-2
... manufactured from an unkilled carbon-deficient steel, and were case hardened to a depth of 0.8 to 0.9 mm. The peripheral structure at the places not showing wear consisted of coarse acicular martensite with a high percentage of retained austenite. The links therefore were strongly overheated, probably directly...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.steel.c9001159
EISBN: 978-1-62708-232-7
.... 8 × Figure 3 shows the transition from the mild steel pipe to the welding material that had frozen in position. The otherwise fine-grained ferritic-pearlitic microstructure of the unalloyed pipe ( Fig. 4 ) has become coarse-grained and acicular (Widmanstätten structure).The microstructure...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0048757
EISBN: 978-1-62708-234-1
... surface embrittlement resulted from oxygen absorption which made the surface layers susceptible to cracking under start up and shutdown. Replacement tubes made of a heat-resistant alloy (e.g., Hastelloy C-276) were recommended. Acicular structure Overheating Tubes ASTM B337 grade 2 UNS R50400...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.usage.c9001434
EISBN: 978-1-62708-236-5
... , it was associated with hardening cracks of the weld under-bead variety. Microscopical examination confirmed these indications and showed the hardened layer to have an acicular structure characteristic of martensite; Figure 3 includes some of the fine cracks associated with this zone. The unaffected material...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.power.c0048814
EISBN: 978-1-62708-229-7
... and submerged arc portions of the weld. The HAZ had a more acicular structure normally associated with untempered martensite. Scanning electron microscopy of the failure surface of the plug sample revealed striations of the type normally associated with progressive or fatigue-type failures ( Fig. 2...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.mech.c0047187
EISBN: 978-1-62708-225-9
... side ( Fig. 1b ) consisted of coarse acicular martensite with a large percentage of retained austenite. Parts with such a structure usually have a relatively low wear resistance because of low hardness. They are also very sensitive to shock because of their large grain size. Fig. 1 Forged 1.60Mn...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0048289
EISBN: 978-1-62708-234-1
... the ruptured and the unruptured tubes were examined metallographically at a magnification of 500 * . Near the rupture edge in the failed tube, the microstructure consisted of ferrite and acicular martensite or bainite ( Fig. 1a ). There were no indications of a cold-worked structure in this area; hardness...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.conag.c9001501
EISBN: 978-1-62708-221-1
...–59 HRC, which is within the specification of 58–63 HRC. The core structure contains an equal admixture of low-carbon martensite and lamellar pearlite. The case structure displays a very fine acicular martensite retaining less than 5% austenite. The pitted area low on the active profile shows...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.conag.c9001449
EISBN: 978-1-62708-221-1
... showing the characteristic “woolly” appearance associated with such a zone. In the centre of each grain, however, a region showing a different structure was present, and higher magnification revealed this to have n angular, acicular form as depicted in Figure 5 . Scratch tests revealed no significant...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.steel.c9001645
EISBN: 978-1-62708-232-7
... acicularity as compared to martensite in the inner-race sample, indicating higher hardness. Microhardness measurements revealed that, while the hardness levels in core regions of the roller-bearing and inner-race samples were similar, the surface microhardness of the roller bearing was harder than...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0001811
EISBN: 978-1-62708-180-1
.... In most applications, many materials may be satisfactory for a particular part, but only a few materials will be optimum. In hardenable steels, tempered martensite has greater fatigue resistance than mixed structures. From a practical and theoretical aspect, alloy steels are a better material...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.steel.c9001245
EISBN: 978-1-62708-232-7
... consisted of very fine acicular martensite with fine spherical carbide inclusions ( Fig. 6 ) up to a depth of 5–6 mm. The martensite indicated no signs of tempering treatment. Adjoining the purely martensitic peripheral zone was a transition zone with increasing amount of bainite and pearlite from...
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0009222
EISBN: 978-1-62708-180-1
... tool material has an acicular martensitic structure (right) that cracks easily (see Fig. 5 ). Etchant, Nital; 700X. Figure 5 shows a die that cracked because overheating had formed an acicular-martensitic structure (righthand micrograph in Fig. 4 ). Low hardening temperatures...
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001369
EISBN: 978-1-62708-215-0
... ). There also appeared to be a small crack under the light-colored metal ( Fig. 6 ). Fig. 5 Dendritic structure of weld buildup. Etched with Kalling's reagent. 95× Fig. 6 Interface of weld buildup and base metal. Weld is on left (white, unetched), martensite on right (black and white, acicular...