Fracture mechanisms and microstructure in a medium Mn quenching and partitioning steel exhibiting macrosegregation

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

卷:754

Article

Hidalgo, J.¹  Celada-Casero, C.¹  Santofimia, M. J.¹ 

[1] Delft Univ Technol, Dept Mat Sci & Engn, Mekelweg 2, NL-2628 CD Delft, Netherlands

关键词: Quenching and partitioning;    Medium manganese steels;    Microstructure;    Fracture mechanisms;   

DOI  :  10.1016/j.msea.2019.03.055

来源: Elsevier

【 摘 要 】

A medium-Mn steel, exhibiting manganese macrosegregation, was investigated. In order to study how the microstructure development influences the fracture mechanisms, the steel was quenching and partitioning processed using two different partitioning temperatures. At 400 degrees C partitioning temperature, the microstructure exhibits intergranular fracture at low plastic strain, following Mn-rich regions in which fresh martensite predominates. Elongated thin precipitates at prior austenite grain boundaries facilitate the initiation and progress of cracks at these locations. After partitioning at 500 degrees C, the redistribution of carbon triggers the formation of pearlite, the precipitation of carbides in the carbon-enriched austenite and the formation of spheroidal carbides at prior austenite grain boundaries. All these microstructural features result in an interlath fracture with more ductile character than after partitioning at 400 degrees C. In both cases, manganese macrosegregation triggers brittle fracture mechanisms by creating large hardness gradients.

【 授权许可】

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