One-step annealing optimizes strength-ductility tradeoff in pearlitic steel wires

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

卷:757

Article

Xiang, L.^1,2,3  Liang, L. W.^1,3  Wang, Y. J.^1,3  Chen, Y.^1,3  Wang, H. Y.^1,3  Dai, L. H.^1,3 

[1] Chinese Acad Sci, Inst Mech, State Key Lab Nonlinear Mech, Beijing 100190, Peoples R China

[2] China Acad Engn Phys, Inst Syst Engn, Mianyang 621999, Sichuan, Peoples R China

[3] Univ Chinese Acad Sci, Sch Engn Sci, Beijing 101408, Peoples R China

关键词: Pearlitic steel wire;    Carbon state;    Annealing;    Strength and ductility;    Atomistic simulations;   

DOI  :  10.1016/j.msea.2019.04.086

来源: Elsevier

【 摘 要 】

In this paper, the mechanical properties of a cold-drawn wire (epsilon = 2.43) are modulated by simple annealing and the variation of its microstructure is characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and molecular dynamics (MD) simulation. The tensile ductility of the wire can be improved for about three times without compromising its strength when being annealed at 325 degrees C for 10-30 min. It is convinced that solid solution of carbon atoms from decomposed cementite lamellae improve the wire strength at low temperature annealing (up to 250 degrees C) and make the wire strength basically equal the as-drawn state even though cementite lamellae are weakened by cementite recrystallization at 325 degrees C. And reversely the weakening cementite layers lead to the great improvement of wire ductility at this time since it relaxes the restriction to the moving of dislocations. At higher annealing temperature, the wire strength decreases with the growth of cementite and ferrite grains. The appearance of nano-recrystallized cementite grains at a medium annealing temperature may be a critical factor governing the enhanced wire mechanical properties.

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