Effect of a heat treatment on the precipitation behavior and tensile properties of alloy 690 steam generator tubes

JOURNAL OF NUCLEAR MATERIALS

卷:479

Article

Lee, Tae-Hyuk^1,2  Suh, Ho-Young³  Han, Seul-Ki^1,4  Noh, Jae-Soo⁵  Lee, Jong-Hyeon^1,4 

[1] Chungnam Natl Univ, Dept Mat Sci & Engn, 99 Daehak Ro, Daejeon 34134, South Korea

[2] Univ Sheffield, Dept Mat Sci & Engn, Robert Hadfield Bldg, Sheffield S1 3JD, S Yorkshire, England

[3] Korea Basic Sci Inst, Div Elect Microscop Res, Daejeon 34133, South Korea

[4] Chungnam Natl Univ, Rapidly Solidified Mat Res Ctr, Daejeon 34134, South Korea

[5] KEPCO Nucl Fuel Co Ltd, New Project Ctr, 989 Daedeokdae Ro, Daejeon 34039, South Korea

关键词: Alloy 690;    Heat treatment;    M23C6 carbide;    Grain boundary character;    Tensile properties;   

DOI  :  10.1016/j.jnucmat.2016.06.038

来源: Elsevier

【 摘 要 】

The intergranular carbide precipitation behavior and its effect on the tensile properties were investigated in alloy 690. The precipitation of intergranular carbides, identified as Cr-rich M23C6, was retarded on the low-angle grain boundaries and the coincidence-site lattice boundaries. The M23C6 carbides have a cubecube orientation relationship with the matrix. The ultimate tensile strength, yield strength, and elongation of the solution annealed alloy 690 are 648.2 +/- 8.2 MPa, 242.8 +/- 10.5 MPa and 44.9 +/- 2.3%, respectively. The ultimate tensile strength and the yield strength increased to 764.8 +/- 7.8 MPa and 364.8 +/- 10.2 MPa until the aging time reached 16 h. This increase is ascribed to the M23C6 carbide acting as reinforcements. However, when the aging time exceed 16 h, these properties gradually decreased with increasing aging time. The decrease in ultimate tensile strength, yield strength, and elongation were mainly caused by the intergranular cracking due to the low bond strength between the carbide and the matrix. (C) 2016 Elsevier B.V. All rights reserved.

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