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Ke Yang – One of the best experts on this subject based on the ideXlab platform.

  • Processing of Ultralow Carbon Pipeline Steels with Acicular Ferrite
    Journal of Materials Science & Technology, 2009
    Co-Authors: Xiao Furen, Ming-chun Zhao, Yiyin Shan, Bo Liao, Ke Yang
    Abstract:

    Acicular Ferrite microstructure was achieved for an-ultralow carbon pipeline,steel through the improved thermomechanical control process (TMCP), which was based on the transformation process of deformed austenite of steel. Compared with commercial pipeline steels, the experimental ultralow carbon pipeline steel possessed the satisfied strength and toughness behaviors under the current improved TMCP, although it contained only approximately 0.025% C, which should mainly be attributied to the microstructural characteristics of Acicular Ferrite.

  • challenge of mechanical properties of an Acicular Ferrite pipeline steel
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006
    Co-Authors: Yiyin Shan, Bo Liao, Furen Xiao, Gui-ying Qiao, Chunling Zhang, Yong Zhong, Ke Yang
    Abstract:

    In modern industry, the developing tendency and prospect for productions of the oil and gas pipeline steels is to further improve the strength and toughness by advanced manufacture process of the thermo-mechanical control process (TMCP) to refine microstructure. In this work, the hot deformation behavior as well as its effect on the phase transformation of the clean Acicular Ferrite pipeline steel with simple chemical composition has been investigated. According to the result, the optimum TMCP parameters were designed. Furthermore, the rolling test was carried out on the experimental rolling mill. The results show that, the high strength and excellent toughness of the clean Acicular Ferrite pipeline steel can be obtained by controlling the TMCP parameters of the production process appropriately. (c) 2006 Elsevier B.V. All rights reserved.

  • Effects of Chemical Composition and Hot Deformation on Continuous Cooling Transformation Behavior of Acicular Ferrite Pipeline Steels
    Multidiscipline Modeling in Materials and Structures, 2006
    Co-Authors: Furen Xiao, Yiyin Shan, Bo Liao, Gui-ying Qiao, Chunling Zhang, Yong Zhong, Ke Yang
    Abstract:

    As an optimal microstructure of pipeline steels, Acicular Ferrite is widely found in steels used in oil and gas pipeline transportation because it possesses both high strength and good toughness. In this paper, the microstructure of Acicular Ferrite and its continuous cooling transformation (CCT) diagrams of six steels with different carbon and alloy additions have been studied by using dilatometry, optical metallography. And the effects of different hot deformation processes on the CCT diagrams and microstructures have also been studied. Furthermore, the effects of microalloyed elements and hot deformation on continuous cooling transformation have been discussed. The results show that lower carbon content and alloy additions such as Mn, Nb, Ti, Mo, Ni and/or Cu in steels will promote the formation of Acicular Ferrite. The hot deformation promotes the Acicular Ferrite transformation and refines the microstructures of final products.

H. K. D. H. Bhadeshia – One of the best experts on this subject based on the ideXlab platform.

  • chapter 7 Acicular Ferrite
    Steels: Microstructure and Properties (Fourth edition), 2017
    Co-Authors: H. K. D. H. Bhadeshia
    Abstract:

    Non-metallic inclusions are anathema when it comes to the design of strong steels because they become the initiation sites for fracture. Huge efforts have been made devoted to making clean steels – the oxygen concentration of a hard bearing steel is routinely less than 10 ppm. However, there are other structural steels that have to be welded where the localised heat input generates microstructures in the heat-affected zone that are undesirable. The alloys that are used to deposit the weld must have good properties in the as-cast state. In both of these circumstances, specific non-metallic inclusions are a positive boon in that they provide substrates for the intragranular nucleation of bainite. As a consequence, highly organised sheaves of bainite are altered into a more chaotic arrangement that frequently deflects propagating cracks and hence enhances the toughness. This is the so-called Acicular Ferrite that is the subject of this chapter.

  • 7 Acicular Ferrite
    Steels (Third Edition)#R##N#Microstructure and Properties, 2006
    Co-Authors: H. K. D. H. Bhadeshia
    Abstract:

    Publisher Summary This chapter deals with the mechanism by which Acicular Ferrite forms and the role of inclusions in stimulating its formation. Bainite and Acicular Ferrite have essentially the same transformation mechanism, but their microstructures differ in detail because the former nucleates at grain surfaces and hence it grows in the form of sheaves of parallel platelets. Acicular Ferrite, on the other hand, nucleates intragranularly on non-metallic inclusions, which are in effect point nucleation sites. The platelets of Acicular Ferrite therefore radiate from the individual inclusions, thus generating a microstructure, which is much more disorganized with adjacent platelets pointing in different directions. There are many kinds of non-metallic inclusions, which are effective in stimulating intragranular nucleation, but some titanium compounds are found to be particularly potent. The exact mechanism of nucleation remains to be resolved. Acicular Ferrite grows without diffusion, but the excess carbon is not retained in the supersaturated Ferrite. It is partitioned into the residual austenite shortly after growth. The transformation is accompanied by shear, and rather smaller dilatational displacements, which together with the reproducible orientation relationship, the plate shape and lack of chemical composition change fit a displacive mechanism of transformation.

  • Effect of plastic deformation on the formation of Acicular Ferrite
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2003
    Co-Authors: C.h. Lee, H. K. D. H. Bhadeshia, Hu-chul Lee
    Abstract:

    Abstract The effect of plastic deformation on the transformation of austenite to Acicular Ferrite in a Fe–Mn–Si–C alloy steel containing non-metallic inclusions was investigated. The transformation to Acicular Ferrite is retarded and the final fraction of Acicular Ferrite is reduced in plastically deformed austenite, which is a characteristic of a displacive transformation mechanism. The increase in the chemical driving force for transformation due to large undercooling below the Bs temperature overcomes the efficacy of dislocations in preventing the growth of Acicular Ferrite.

Ming-chun Zhao – One of the best experts on this subject based on the ideXlab platform.

  • Processing of Ultralow Carbon Pipeline Steels with Acicular Ferrite
    Journal of Materials Science & Technology, 2009
    Co-Authors: Xiao Furen, Ming-chun Zhao, Yiyin Shan, Bo Liao, Ke Yang
    Abstract:

    Acicular Ferrite microstructure was achieved for an-ultralow carbon pipeline,steel through the improved thermomechanical control process (TMCP), which was based on the transformation process of deformed austenite of steel. Compared with commercial pipeline steels, the experimental ultralow carbon pipeline steel possessed the satisfied strength and toughness behaviors under the current improved TMCP, although it contained only approximately 0.025% C, which should mainly be attributied to the microstructural characteristics of Acicular Ferrite.

  • Acicular Ferrite formation during hot plate rolling for pipeline steels
    Materials Science and Technology, 2003
    Co-Authors: Ming-chun Zhao, Y.-y. Shan, F.-r. Xiao, Ke Yang
    Abstract:

    The transformation of supercooled austenite in a commercial pipeline steel was investigated by means of continuous cooling transformation (CCT) and hot simulation experiments. Based on the obtained results, an improved thermomechanical control process (TMCP) was proposed, which could produce a mixed microstructure dominated by Acicular Ferrite. Results indicated that an increase in the cooling rate could improve the percentage of Acicular Ferrite in the final microstructure under the present experimental conditions. Furthermore, the Acicular Ferrite dominated microstructure could be obtained by a two stage controlled rolling in the austenite recrystallisation region plus the non-recrystallisation region and controlled cooling at a cooling rate of 30 K s(-1).

  • Comparison on strength and toughness behaviors of microalloyed pipeline steels with Acicular Ferrite and ultrafine Ferrite
    Materials Letters, 2002
    Co-Authors: Ming-chun Zhao, Ke Yang, Yiyin Shan
    Abstract:

    A laboratory smelted microalloyed pipeline steel was conducted by two different thermomechanical control process (TMCP) on a pilot rolling mill to produce two currently interesting microstructures, i.e., Acicular Ferrite and ultrafine Ferrite. Strength and toughness behaviors of these two microstructures were investigated. Compared with commercial pipeline steels, the experimental steel with Acicular Ferrite and/or ultrafine Ferrite possessed the satisfied strength and toughness behaviors, although this steel contained only about 0.025% carbon. Furthermore, Acicular Ferrite was better candidate microstructure for pipeline steels than ultrafine Ferrite. (C) 2002 Elsevier Science B.V All rights reserved.