journal article·2016-10Open access

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

Tae-Hyuk Lee, Ho-Young Suh, Seul-Ki Han, Jae-Soo Noh, Jong-Hyeon Lee

Abstract

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 cube-cube 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.
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Research context

OpenAlex topics: High Temperature Alloys and Creep · Nuclear Materials and Properties · Metal Alloys Wear and Properties

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