Mechanical and microstructural behavior of a heterogeneous austenitic stainless steel processed by Equal Channel Angular Sheet Extrusion (ECASE)

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

卷:792

Article

Alberto Munoz, Jairo^1,2  Komissarov, Alexander²  Avalos, Martina¹  Bolmaro, Raul E.¹ 

[1] Univ Nacl Rosario, Inst Fis Rosario, Consejo Nacl Invest Cient & Tecn CONICET, RA-2000 Rosario, Argentina

[2] Natl Univ Sci & Technol MISIS, Moscow 119049, Russia

关键词: Phase transformation;    Strain;    Heterogeneous microstructure;    Tensile strength;    Dislocations;   

DOI  :  10.1016/j.msea.2020.139779

来源: Elsevier

【 摘 要 】

A sheet-shaped austenitic stainless steel (ASS) was processed by one ECASE pass. In this way, larger deformations were introduced close to the sheet edge vicinities, while the middle zone remained less affected by the deformation. The heterogeneous deformation produced larger amounts of deformation induced martensite (DIM) at the sheet edges, resulting in a heterogeneous structure along the sheet thickness. Tensile tests revealed that after the deformation process the material increased its yield strength more than 3 times from 200 MPa in its initial state to similar to 690 MPa after one ECASE pass. Tensile tests for the processed material in different zones of sheet thickness revealed the existence of two types of materials, one more resistant and less ductile (near the edges) and other more ductile, but less resistant (in the middle zone). Because of the heterogeneity, higher dislocation densities were found in the edges than in the middle of the sheet, giving rise to a plastic deformation gradient in which the region near the edge is capable of withstanding greater plastic deformations by generating a plastic instability as soon as the deformation starts. Through a rule of mixtures, it was found that the greatest strength contribution of the heterogeneous material came from the dislocations on the bcc martensite developed near the sheet edges.

【 授权许可】

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