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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
... 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 examination...
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
... 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.process.c9001214
EISBN: 978-1-62708-235-8
... 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 necessary...
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
... 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 probable...
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
... 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 heated during...
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
... 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 of the welding seam...
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.power.c0048814
EISBN: 978-1-62708-229-7
... the shielded metal arc 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...
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.mech.c0047187
EISBN: 978-1-62708-225-9
... in peripheral speed. The microstructure at the periphery of a worn tooth at its unworn 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...
Image
Published: 01 January 2002
Fig. 4 A properly heat treated tool of manganese oil-hardening steel has a martensitic structure (left) containing fine tempered martensite and carbides. An overheated tool material has an acicular martensitic structure (right) that cracks easily (see Fig. 5 ). Etchant, Nital; 700X. More
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 microstructure near the rupture edge was revealed by metallographic examination to consist of ferrite and acicular martensite or bainite. The microstructure and the observed lack of cold work indicated a temperature above the transformation temperature of 727 deg C had been reached. Swelling of the tubes...
Image
Published: 01 January 2002
(A) and the as-forged (acicular) microstructure (B). The black square shapes (C) are diamond pyramid hardness indentations. More
Image
Published: 30 August 2021
(A) and the as-forged (acicular) microstructure (B). The black square shapes (C) are diamond pyramid hardness indentations. More
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
... 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 the exterior to the interior...
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
... and a case hardness traverse. Microscopic Examination 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 evidence...
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
... Interface of weld buildup and base metal. Weld is on left (white, unetched), martensite on right (black and white, acicular). A crack is visible under the weld. 2% nital etch. 190× Chemical Analysis/Identification Results of the chemical analysis of the shaft are shown in Table 1 , along...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.matlhand.c0048073
EISBN: 978-1-62708-224-2
..., a small ductile shear lip, was approximately 30° off-center, indicating low stress and rotational bending. The shaft material was 1030 steel, as specified, and had a slightly acicular fine-grain structure. Conclusion The shaft failed by fatigue fracture, which originated at a sharp corner...
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.conag.c9001497
EISBN: 978-1-62708-221-1
...-carbon martensite. This indicates a well quenched and tempered structure. Case structure: Acicular martensite retaining approximately 10% austenite near the surface. Excellent structure for material and heat treatment. Case depth: (specified 0.075–0.090 in.) 0.085 in. effective depth...