The valuation of microstructural evolution in a thermo-mechanically processed transformation-twinning induced plasticity steel during strain hardening

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:754

Article

Sabzi, H. Eskandari¹  Zarei-Hanzaki, A.¹  Kaijalainen, A.²  Kisko, A.² 

[1] Univ Tehran, Coll Engn, Sch Met & Mat Engn, Hot Deformat & Thermomech Proc High Performance E, Tehran, Iran

[2] Univ Oulu, Ctr Adv Steels Res, Mat & Prod Engn, Oulu, Finland

关键词: Transformation-twinning induced plasticity steel;    Dislocation;    Deformation twins;    Martensitic transformation;    alpha-'-martensite;    Texture evolution;   

DOI  :  10.1016/j.msea.2018.09.068

来源: Elsevier

【 摘 要 】

The successive evolution of martensitic transformation, twining and dislocation substructure formation in a transformation-twinning induced plasticity steel during room temperature straining was studied in the present work. This was materialized through microstructural observations and micro-texture examinations utilizing the electron backscattered diffraction method. To evaluate the strain hardening behaviour of the thermo-mechanically processed steel, tensile testing procedure to different strains at ambient temperature was practiced. The results indicated that the dislocation slip, mechanical twinning, and deformation induced epsilon/alpha'-martensite formation were involved as the deformation mechanisms. At the early stages of deformation, the dynamic formation of dislocation substructure, strain induced epsilon-martensite and twins from austenite played the main role in the observed work hardening behaviour. Furthermore, the results demonstrated that the formation of alpha'martensite was the dominant deformation mechanism at higher deformation levels. The corresponding texture analysis indicated to a double fibre texture formation, with a relatively stronger < 111 > at lower strains and a stronger < 100 > partial fibre parallel to tensile axis at higher strains. However, in the latter, the Cube, A and Goss Twin (GT)-type textures were dominated. Decreasing of the Goss and S components were attributed to the preferential transformation of austenite to alpha' - and epsilon martensites, respectively. The presence of GT component even at higher strains approved the participation of deformation induced twinning as a dominant deformation mechanism up to failure.

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