On the origin and contribution of extended kinks and jogs and stacking fault ribbons to deformation behavior in an ultrahigh strength cobalt-free maraging steel with high density of low lattice misfit precipitates

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

卷:728

Article

Li, K.¹  Yu, B.¹  Misra, R. D. K.¹  Han, G.²  Liu, S.³  Shen, Y. F.⁴  Shang, C. J.² 

[1] Univ Texas El Paso, Dept Met Mat & Biomed Engn, Lab Excellence Adv Steels Res, 500 W Univ Ave, El Paso, TX 79968 USA

[2] Univ Sci & Technol Beijing, Beijing 1100083, Peoples R China

[3] Shanghai Jiao Tong Univ, Inst Adv Steels & Mat, Sch Mat Sci & Engn, Shanghai 200240, Peoples R China

[4] Northeastern Univ, Mat Sci & Engn, Shenyang 110819, Liaoning, Peoples R China

关键词: Ultrahigh strength steel;    Deformation behavior and mechanism;    Wavy martensite lath;    Dislocation mobility;    Nanotwins;   

DOI  :  10.1016/j.msea.2018.05.039

来源: Elsevier

【 摘 要 】

We elucidate here the deformation mechanisms and underlying reasons that contributed to high ductility (10.2%) and high static toughness (112.5 MJ m(-3)) in an ultrahigh strength (1860 MPa) cobalt-free 19Ni3Mo1.5Ti maraging steel characterized by high density (2.3 x 10(24) m(-3) ) of eta-Ni-3 (Ti,Mo) and B2-Ni(Mo,Fe) nanoscale precipitates with low lattice misfit of < 1% with the martensite matrix. Multiple deformation processes occurred during plastic deformation. Lath-morphology of martensite was dramatically segmented with angles of 30 degrees, 60 degrees or 120 degrees with large pile-up of dislocations at the segmented boundaries. This occurred because of the interactive ability of edge and screw dislocations along the martensite habit planes, which led to kinks and jogs. The low lattice misfit (0.6% similar to 0.9%) precipitates interacted with dislocations leaving stacking fault ribbons within precipitates that build a large long range of back stress producing a high strain-hardening response. Additionally, nanoscale twinning occurred. The above contributions to ductility are envisaged to be in addition to the significantly reduced elastic interaction between the low lattice misfit nanoscale precipitates and dislocations that reduces the ability for crack initiation at the particle-matrix interface.

【 授权许可】

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