Continuous cooling transformation

About: Continuous cooling transformation is a research topic. Over the lifetime, 920 publications have been published within this topic receiving 11336 citations. The topic is also known as: CCT.

Design of novel high strength bainitic steels: Part 1

Abstract: Mixed microstructures consisting of fine plates of upper bainitic ferrite separated by thin films of stable retained austenite have seen many applications in recent years. There may also be some martensite present, although carbides are avoided by the judicious use of silicon as an alloying element. The essential principles governing the optimisation of such microstructures are well established, particularly that large regions of unstable high carbon retained austenite must be avoided. With careful design, impressive combinations of strength and toughness have been reported for high silicon bainitic steels. The aim of the present work was to ascertain how far these concepts could be extended to achieve unprecedented combinations of strength and toughness in bulk samples subjected to continuous cooling transformation, consistent with certain hardenability and processing requirements. Thus, this paper (part 1 of a two part study) deals with the design, using phase transformation theory, of a series ...

Continuous cooling transformation of undeformed and deformed low carbon pipeline steels

Abstract: The continuous cooling transformation (CCT) behaviors of three low carbon pipeline steels containing the different carbon and alloy additions such as Mn, Nb, V, Ti and/or Mo were investigated in the undeformed and deformed conditions, respectively. The corresponding static (without hot deformation) and dynamic (with hot deformation) CCT diagrams were constructed, which almost involved the formation curves of bainitic ferrite, acicular ferrite, polygonal ferrite, and pearlite. It was found that with the exception of V, the aforementioned alloy additions played a significant role in suppressing the formation of polygonal ferrite and promoting the formation of acicular ferrite. Furthermore, hot deformation could also strongly promote the formation of acicular ferrite, that is, the temperature zone of acicular ferrite transformation was enlarged from 400-600 degreesC in the static CCT diagrams to 450-700 degreesC in the dynamic CCT diagrams. The corresponding cooling rate range of acicular ferrite transformation was significantly increased, and the island constituents in acicular ferrite became finer due to hot deformation. (C) 2003 Elsevier Science B.V. All rights reserved.

Atlas of time-temperature diagrams for irons and steels

Abstract: The most comprehensive collection of time-temperature diagrams for irons and steels ever collected. Between this volume and its companion, Atlas of Time Temperature Diagrams for Nonferrous Alloys, you'll find the most comprehensive collection of time-temperature diagrams ever collected. Containing both commonly used curves and out-of-print and difficult-to-find data, these Atlases represent an outstanding worldwide effort, with contributions from experts in 14 countries. Time-temperature diagrams show how metals respond to heating and cooling, allowing you to predict the behavior and know beforehand the sequence of heating and cooling steps to develop the desired properties. These collections are a valuable resource for any materials engineer Both Collections Include: Easy-to-Read Diagrams Isothermal transformation Continuous cooling transformation Time-temperature precipitation Time-temperature embrittlement Time-temperature ordering Materials Included in the Irons and Steels Volume: Low-carbon High Strength Low Alloy Stainless (Maraging, austenitic, ferritic, duplex) Chromium, molybdenum, vanadium, silicon Structural Quenched and tempered Spring and Rail High-temperature creep-resistant Tool and die Eutectoid, hypereutectoid carbon Deep hardening Titanium bearing Irons: Gray cast, malleable, white, white cast, ductile.

Continuous cooling transformations and microstructures in a low-carbon, high-strength low-alloy plate steel

Abstract: A continuous-cooling-transformation (CCT) diagram was determined for a high-strength low-alloy plate steel containing (in weight percent) 0.06 C, 1.45 Mn, 1.25 Cu, 0.97 Ni, 0.72 Cr, and 0.42 Mo. Dilatometric measurements were supplemented by microhardness testing, light microscopy, and transmission electron microscopy. The CCT diagram showed significant suppression of polygonal ferrite formation and a prominent transformation region, normally attributed to bainite formation, at temperatures intermediate to those of polygonal ferrite and martensite formation. In the intermediate region, ferrite formation in groups of similarly oriented crystals about 1 μm in size and containing a high density of dislocations dominated the transformation of austenite during continuous cooling. The ferrite grains assumed two morphologies, elongated or acicular and equiaxed or granular, leading to the terms “acicular ferrite” and “granular ferrite,” respectively, to describe these structures. Austenite regions, some transformed to martensite, were enriched in carbon and retained at interfaces between ferrite grains. Coarse interfacial ledges and the nonacicular morphology of the granular ferrite grains provided evidence for a phase transformation mechanism involving reconstructive diffusion of substitutional atoms. At slow cooling rates, polygonal ferrite and Widmanstatten ferrite formed. These latter structures contained low dislocation densities and e-copper precipitates formed by an interphase transformation mechanism.