Mechanical Behavior of Inconel 625 at Elevated Temperatures

Abstract

The Inconel 625 is a nickel-based alloy has been widely used in the high-temperature application. The Inconel 625 exhibits unstable plastic flow at elevated temperature characterized by serrated yielding, known as Portevin-Le Chatelier effect. The aim of this work is to evaluate the mechanical properties at high temperatures of the Inconel 625. The tensile tests were performed in the temperature range of room temperature until 1000 °C and strain rate of 2x10^-4 to 2x10^-3 s^-1. The creep tests were performed in the temperature range of 600-700 °C, in the stress range of 500-600 MPa in a constant load mode. The surface fracture was observed by optical and scanning electron microscopy. Serrated stress-strain behavior was observed in the curves obtained at 200 to 700 °C, which was associated with the dynamic strain aging effect. The yield strength and the elongation values show an anomalous behavior as a function of the test temperature. An intergranular cracking was observed specimen tensile tested at 500 °C that can be attributed to the decohesion of the carbides along the grain boundaries. The fracture surface of the specimen tensile tested at 700 °C showed the predominance of transgranular cracking with tear dimples with a parabolic shape.

Comportamento microestrutural e de fluência do Inconel 718 após tratamento térmico de duplo envelhecimento

“…Observou-se um padrão de aumento dos valores de t p , t f e ε f, e diminuição na s ε promovendo uma redução na velocidade de deformação por fluência com a aplicação de tratamento de duplo envelhecimento. Essa diminuição na taxa secundária de fluência implicou no aumento de resistência, uma vez que a diminuição da taxa secundária propiciou a redução na taxa de velocidade de deformação do material, promovendo maior tempo de vida, cuja tendência no comportamento em fluência também foi reportada por autores [3,5]. Esses fatores indicaram um aumento na resistência à fluência da liga após o tratamento térmico de duplo envelhecimento, que ocorreu pela precipitação de fases endurecedoras, como as fases γ' e γ", devido ao seu alto valor energético de contorno de fase [8].…”

Development of an Open-source Alloy Selection and Lifetime Assessment Tool for Structural Components in CSP

“…Although In the case of the solid solution strengthened alloy 625, the creep degradation mechanisms have not been unambiguously identified in the literature. The presence of additional intermetallic precipitates such as δ-Ni 3 Nb phase and (Mo,Si)-rich M 6 C-type carbides might additionally be contributing to the creep strength of 625 [64]. The temperature dependence of sum of phase fractions of δ-Ni 3 Nb phase and M 6 C carbides 𝝋𝝋 δ+M 6 C was calculated with the thermodynamic database TCNI8 [53].…”

Creep and Mechanical Behavior Study of Inconel 718 Superalloy

“…Nickel-based superalloys are known since the 1930s, and used primarily in aerospace applications [1][2][3][4] . These applications require a material with high mechanical strength 5,6 , good resistance to fatigue and creep [7][8][9][10] , good corrosion resistance 11 , and ability to operate continuously at elevated temperatures 11,12 .…”

“…Inconel 718 superalloy exhibits excellent mechanical properties and corrosion resistance at elevated temperatures 19 . However, brittle intergranular cracking is observed when the alloy is deformed at elevated temperatures 5,18,[20][21][22][23] . The mechanical properties are influenced by Dynamic Strain Aging (DSA) and the embrittlement effect is related to grain boundary penetration by oxygen.…”