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A. R. Marder

Bio: A. R. Marder is an academic researcher from Bethlehem Steel. The author has contributed to research in topics: Martensite & Lath. The author has an hindex of 1, co-authored 1 publications receiving 284 citations.
Topics: Martensite, Lath, Bainite, Austenite

Papers
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Journal ArticleDOI
01 Sep 1971
TL;DR: In this article, the main structural differences between the two major types of martensite in ferrous alloys are discussed in terms of their possible effects on the plastic deformation mechanisms which must occur in the parent austenite and product martensites during transformation.
Abstract: Light and electron microscopy have been used to determine the main structural differences between the two major types of martensite in ferrous alloys. In the martensite that forms in dilute alloys of iron, the basic transformation unit takes the shape of a lath, and hence the term lath martensite is appropriate for identifying this morphology. Each lath is the result of a homogeneous shear, and successive shears produce a packet of parallel laths containing a high density of tangled dislocations. The other type, plate martensite, differs in the shape taken by a transformation unit and its transformation sequence is characterized by nonparallel plate formation. Investigation of a large number of binary ferrous systems shows that alloy composition and the transformation temperature influence the transition from lath to plate martensite. These two factors are discussed in terms of their possible effects on the plastic deformation mechanisms which must occur in the parent austenite and product martensite during transformation.

313 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the authors reviewed the strengthening mechanisms associated with the various components of martensitic microstructures in steels and other ferrous alloys and examined the experiments and strengthening theories associated with FeNi and FeNi-C alloys, in which the martensite, because of subzero temperatures, can be evaluated with carbon atoms trapped in octahedral interstitial sites.
Abstract: This paper reviews the strengthening mechanisms associated with the various components of martensitic microstructures in steels and other ferrous alloys. The first section examines the experiments and strengthening theories associated with Fe–Ni and Fe–Ni–C alloys, in which the martensite, because of subzero Ms temperatures, can be evaluated with carbon atoms trapped in octahedral interstitial sites. The evaluation of strengthening in these alloys has been limited to interpreting yield strength of unaged, untempered martensite in terms of interstitial solid solution strengthening. The second section reviews strengthening of martensitic Fe–C alloys and low-alloy carbon steels with above-room-temperature Ms temperatures. In these alloys, it is impossible to prevent C diffusion during quenching, and strengthening of martensite becomes dependent on static and dynamic strain aging due to carbon atom interaction with dislocation substructure. In all alloys the dominant strengthening component of martensitic microstructures is the matrix of martensitic crystals, either in lath or plate morphology, but secondary effects due to other microstructural components such as carbides and retained austenite are also discussed.

720 citations

Journal ArticleDOI
TL;DR: The morphology and crystallography of lath martensite in two Mn-containing interstitial free steels and a maraging steel were examined in detail by a combination of transmission electron microscopy, electron backscatter diffraction in a scanning electron microscope and optical microscopy.

641 citations

Journal ArticleDOI
TL;DR: In this article, porosity levels in Stainless Steel (SS) 316L parts manufactured with SLM were studied in relation to the effects of process parameters on microstructure and material hardness.

272 citations

Journal ArticleDOI
TL;DR: The morphology of continuously cooled bainite in steels is examined in this article and compared with that of isothermally transformed bainites, and a classification system for bainitic microstructures is also developed.
Abstract: The morphology of continuously cooled bainite in steels is examined in this review and compared with that of isothermally transformed bainite. Some experimental observations of microstructures in continuously cooled commercial steels are also presented; these results demonstrate the presence of microstructures which are not easily defined in terms of any of the “classical” bainitic morphologies. The numerous terms created over the last 50 years to describe specific bainite morphologies have led to some confusion, and it is suggested that the commonly used terminologies do not adequately describe the full range of bainitic microstructures which are observed. A general definition for the bainite transformation is proposed. A classification system for bainitic microstructures is also developed, encompassing both isothermally transformed and continuously cooled bainites. It is suggested that primary bainite morphologies be classified as B1, B2, or B3, depending on whether the acicular ferrite is associated with (1) intralath precipitates, (2) interlath particles/films, or (3) discrete regions of retained austenite and/or secondary transformation product(e.g., martensite or pearlite), respectively. Possible ambiguities with the descriptions of autotempered martensite and Widmanstatten ferrite are also discussed, and a number of areas are identified where further work would be helpful.

228 citations

Journal ArticleDOI
TL;DR: In this paper, a detailed qualitative and quantitative microstructural examination of four dual-phase steels has been carried out, and it has been found that during tensile deformation, martensite islands do not deform until strains well in excess of the maximum uniform strain have been reached.
Abstract: A detailed qualitative and quantitative microstructural examination of four dual-phase steels has been carried out. Dual-phase structures were produced in three of these steels by intercritical annealing; the other was in the as-rolled condition. Similar combinations of tensile properties were obtained with all four steels. In intercritically annealed material, greater austenite hardenability was encountered with the two steels containing strong carbide-forming elements (vanadium or titanium) than with a similar plain carbon steel. It has therefore been proposed that the carbonitride precipitates (which are present during the anneal) inhibit the movement of the austenite/ferrite interface during the post-anneal quench; strong metallographic evidence has been provided to support this view. It has been found that during tensile deformation, martensite islands do not deform until strains well in excess of the maximum uniform strain have been reached; this observation has enabled the successful applic...

223 citations