부산대학교 도서관

In order to research the hot deformation of Inconel 625 deposited metal, the Inconel 625 flux-cored wire was surfaced on carbon steel by GMAW. The true stress–strain curves of the deposited metal were obtained by high-temperature tensile test at temperatures of 600–900 °C and strain rate of 8.33 × 10−5 s−1. The tensile fracture morphology and microstructure were observed by OM, SEM, XRD and TEM, and the thermal deformation behavior and strengthening mechanism of the Inconel 625 deposited metal were analyzed. The results show that the longitudinal section of the tensile fracture of specimen can be judged to be mainly composed of γ austenite, MC and Laves phase at different temperatures. And the flow stress decreases with the increase of temperature. The tensile stress–strain curves of the specimens show obvious work-hardening behavior after yielding at RT, 600 °C and 700 °C, while it decreases obviously, and the stress basically maintains a constant at 760 °C, 800 °C and 900 °C. When the temperature is 700 °C, the plasticity of the sample has a low valley, that is medium temperature brittleness. Inconel 625 deposited metal is divided into three stages by Arrhenius relation: the low-temperature zone (T ≤ 600 °C), the medium-temperature zone (600 °C < T ≤ 760 °C) and the high-temperature zone (T > 760 °C). In the low-temperature zone, it consists of a/2 < 110 > dislocation pairs cutting the precipitates or continuous cutting matrix channel and stacking faults of precipitates (continuous stacking fault). The strengthening mechanism is dominated by dislocations cutting γ-phase. With the increase of temperature, some dislocation bands and loops appear in the microstructure, and the dislocation bypass mechanism (Orowan mechanism) has been initiated; in the medium-temperature zone, the complex dislocation reactions occur and form dislocation locks and tangles at 700 °C; it is a mixed mechanism of dislocation cutting and bypassing; in the high-temperature zone, a large number of dislocation loops appear in the microstructure, and some irregular dislocation networks can be observed. With the increase of temperature, the dislocation networks become more regular. It shows that the bypass mechanism of dislocation is the main deformation mechanism. [ABSTRACT FROM AUTHOR]