首页|Precipitates evolution and fracture mechanism of the isothermally solidified TLP bonding joints between 316LN stainless steel and IN718 Ni-based alloy

Precipitates evolution and fracture mechanism of the isothermally solidified TLP bonding joints between 316LN stainless steel and IN718 Ni-based alloy

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  • Elsevier
In this study, the dissimilar TLP bonding joints of Inconel 718 nickel-base alloy and AISI 316LN stainless steel free of brittle athermal solidification zone (ASZ) were obtained. It was recognized that a good metallurgical bonding is achieved at the interface between the isothermal solidification zone (ISZ) and diffusion affected zone on the side of IN718 alloy (hereafter referred to as DAZ-IN718), while the interface of ISZ and DAZ-316LN is more sensitive to crack initiation. A lot of precipitates were found in DAZ on both sides near the base metal, which were identified as Cr_2B, Cr_5B_3, Nb_3B_2, and BN. Moreover, two different sizes of voids form at the ISZ/DAZ-316LN interface. The bigger voids are caused by BN phases, while the smaller voids were identified as Kirkendall voids. The tensile test results indicate that the tensile strength and elongation decrease with increasing bonding time. In-situ tensile tests and digital image correlation (DIC) analysis indicate that there are two factors that cause the fracture of dissimilar TLP bonding joints at the ISZ/DAZ-316LN interface. The first factor is the brittle BN phases and Kirkendall voids at the ISZ/DAZ-316LN interface. During tensile tests, dislocations slide along the slip surface until they are blocked by precipitates in the DAZ, resulting in extremely high-stress concentrations at these locations. Moreover, the second factor is the poor ability of DAZ-316LN to resist plastic deformation. The high degree of strain concentration in DAZ-316LN also promotes the formation of microcracks at the ISZ/DAZ-316LN interface.

Transient liquid phase (TLP) bondingIN718 Ni-based alloy316LN steelBN phasesKirkendall voidsIn-situ tensileDigital image correlation (DIC)

Miao Yang、Yu Wang、Ran Ding、Qianying Guo、Chenxi Liu、Yongchang Liu

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State Key Laboratory of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University, Tianjin, 300354, China

Nuclear Power Institute of China, Chengdu, 610225, China

2023

10.1016/j.msea.2023.145440

Materials science and engineering, A. Structural materials

Materials science and engineering, A. Structural materials

ISSN：0921-5093
年,卷(期)：2023.881(Aug.10)
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