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needle-like martensite

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Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 1999
DOI: 10.31399/asm.tb.lmcs.t66560005
EISBN: 978-1-62708-291-4
..., untwinned martensite, slipped martensite, plain martensite, low-carbon martensite, acicular low-carbon martensite, carbon-lean martensite, needle-like martensite , etc. Plate martensite forms as isolated (ideally) lenticular crystals in a wide range of sizes and with a substructure predominantly...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2007
DOI: 10.31399/asm.tb.smnm.t52140021
EISBN: 978-1-62708-264-8
... to form and harden the steel. There are similarities and differences between the formation of martensite at room temperature and pearlite at 650 °C (1200 °F). Like the pearlite, the martensite will start to form (nucleate) along the old austenite grain boundaries, but, unlike the pearlite, the martensite...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2008
DOI: 10.31399/asm.tb.emea.t52240153
EISBN: 978-1-62708-251-8
... by heat treatment is covered in detail. Bainite is an isothermal decomposition product that forms on cooling in the temperature range below that of pearlite but above that of martensite. Like pearlite, bainite forms when austenite (γ) transforms into ferrite (α) and cementite (Fe 3 C). Bainite has...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2002
DOI: 10.31399/asm.tb.mgppis.t60400023
EISBN: 978-1-62708-258-7
... the retained austenite. In some steels, retained austenite is desirable, because it may impart an added degree of ductility to the steel. The following micrographs show retained austenite in a variety of steels. In Fig. 2.37 , retained austenite (white) is seen between plate martensite (dark, needle-like...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 1999
DOI: 10.31399/asm.tb.cmp.t66770171
EISBN: 978-1-62708-337-9
... ). This increase of yield strength is likely a consequence of reduced austenite particle size brought about by the subdivision of austenite volumes by the martensite produced during refrigeration. The ductility indicators, elongation and area reduction, decrease as the temperature of the refrigeration treatment...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2008
DOI: 10.31399/asm.tb.emea.t52240053
EISBN: 978-1-62708-251-8
.... In solids, the atoms are bound much tighter than in liquids and diffuse much more slowly. Instead of transforming directly to the equilibrium phase, metastable transition phases can form prior to forming the final equilibrium phase. Like solidification, nucleation in solid-state reactions is almost always...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2018
DOI: 10.31399/asm.tb.fibtca.t52430351
EISBN: 978-1-62708-253-2
... of ferrite and pearlite at outer surface, 200×. (c) Signs of corrosion and surface decarburization on inner surface of the tube, 200× Fig. 6.155 (a) Outer surface of a tube with linear opening in longitudinal direction. (b) Crack-like discontinuity with wide opening on inner surface Fig...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 2018
DOI: 10.31399/asm.tb.msisep.t59220193
EISBN: 978-1-62708-259-4
....” In either case, in the two-dimensional cross-section they look elongated, “needle-like,” or acicular. Figure 9.11 presents a phenomenological scheme of the martensitic transformation (in two dimensions). Once nucleated, plates will grow rapidly, becoming longer rather than thicker. Growth is interrupted...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2008
DOI: 10.31399/asm.tb.ssde.t52310001
EISBN: 978-1-62708-286-0
... that the characteristic equilibrium phases have been frozen and are then identified by various techniques for structure, composition, and the like. This important work is obviously tedious and susceptible to experimental error and applies only to specific compositions. Any “what if” extrapolation to a different alloy...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2018
DOI: 10.31399/asm.tb.fibtca.t52430027
EISBN: 978-1-62708-253-2
... of its needle-like appearance. Fig. 3.12 shows the temperature range for formation of bainite and its microstructure. At such a low temperature, the distance over which carbon atoms can diffuse is short. As a result, a structure consisting of submicroscopic dispersion of carbides in a matrix of ferrite...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 October 2011
DOI: 10.31399/asm.tb.mnm2.t53060333
EISBN: 978-1-62708-261-7
... growth and good fracture toughness. Another common heat treatment for 2024 is the T8 temper (solution treated, cold worked, and artificially aged). Like the T3 temper, cold working prior to aging helps in nucleating fine precipitates and reduces the number and size of grain-boundary precipitates...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 1999
DOI: 10.31399/asm.tb.cmp.t66770099
EISBN: 978-1-62708-337-9
... is a study of the microstructure of case-hardened steels. It explains what can be learned by examining grain size, microcracking, nonmetallic inclusions, and the effects of microsegregation. It identifies information-rich features, describing their ideal characteristics, the likely cause of variations...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 August 1999
DOI: 10.31399/asm.tb.lmcs.t66560221
EISBN: 978-1-62708-291-4
... is transformed completely to martensite. The lower limit indicates the hardness likely to be obtained with the austenite is quenched to room temperature, when some will remain untransformed. Source: Ref 21 . Fig. 9.19 Martensite formation (oil quench) in transformation of 0.6% C hypoeutectoid steels...
Series: ASM Technical Books
Publisher: ASM International
Published: 30 April 2021
DOI: 10.31399/asm.tb.tpsfwea.t59300179
EISBN: 978-1-62708-323-2
... is martensite, a body-centered tetragonal (bct) atomic structure that appears needle-like under optical microscopy. Special heat treatment called austempering can make steels have a bainitic microstructure that is not as soft as ferrite and not as hard as martensite. Bainitic microstructures are usually opted...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 1996
DOI: 10.31399/asm.tb.phtpclas.t64560003
EISBN: 978-1-62708-353-9
... is named after the German scientist Adolf Martens.) Upon cooling, when the austenite reaches a certain temperature (the martensite-start temperature, M s ), lath or needle-like crystals of martensite form very rapidly inside the austenite grains. The center plane of these crystals is approximately parallel...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2012
DOI: 10.31399/asm.tb.pdub.t53420289
EISBN: 978-1-62708-310-2
... the chance of using a precipitation-hardening heat treatment. The presence of a eutectoid reaction in a phase diagram helps to predict possible heat treatments such as annealing, normalizing, or hardening. It is also possible to predict what heat treatments are likely to be harmful and must be avoided...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 January 1998
DOI: 10.31399/asm.tb.ts5.t65900125
EISBN: 978-1-62708-358-4
... embrittlement are enhanced, and quench cracking is more likely. Fig. 7-4 shows the results of an early study that related the incidence of quench cracking in carbon tool steel to austenitic grain size: The coarser the grain size, the higher the incidence of quench-cracked pieces ( Ref 8 ). Fig. 7-4...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2002
DOI: 10.31399/asm.tb.mgppis.t60400215
EISBN: 978-1-62708-258-7
.... The art of revealing microstructure is the most important tool of the metallographer. An experienced metallographer knows how to use this tool, much like an artist knows how to use and mix the different color paints on his palette to express the mood of his painting. The selection on the metallographer’s...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 1983
DOI: 10.31399/asm.tb.mlt.t62860295
EISBN: 978-1-62708-348-5
... is usually in the shape of plates, laths, or sheets. The typical plate-like ferrous-alloy morphology is illustrated in Fig. 9.4 . Figure 9.4a shows the plate morphology of the product in an Fe–33Ni alloy. [1] Figure 9.4 (a) Martensite plates in Fe–33Ni that formed on cooling to 140 K. (b...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 1983
DOI: 10.31399/asm.tb.mlt.t62860203
EISBN: 978-1-62708-348-5
... point . Most ferrimagnetic materials of technological interest are more well behaved, following curves like those in parts b or c of the figure. Saturation magnetization values for ferrites tend to be about 300 kA·m −1 ( B r ~ 0.4 T), and initial relative permeabilities run from ten to several...