Characterisation of microstructure and creep properties of alloy 617 for high-temperature applications

Abstract

Current energy drivers are pushing research in power generation materials towards improved efficiency and improved environmental impact. In the context of new generation ultra-supercritical (USC) power plant , this is represented by increased efficiency, service temperature reaching 750 o C, pressures in the range of 35 -37.5 MPa and associated carbon capture technology. Ni base alloys are primary candidate materials for long term high temperature applications such as boilers. The transition from their current applications, which have required lower exposure times and milder corrosive environments, requires the investigation of their microstructural evolution as a function of thermo-mechanical treatment and simulated service conditions, coupled with modelling activities that are able to forecast such microstructural changes. The lack of widespread microstructural data in this context for most nickel base alloys makes this type of investigation necessary and novel. Alloy INCONEL 617 is one of the Ni-base candidate materials. The microstructures of four specimens of this material crept at temperatures in the 650 o C-750 o C range for up to 20000 h have been characterised and quantified. Grain structure, precipitate type and location, precipitate volume fraction, size and inter-particle spacing have been determined. The data obtained are used both as input for and validation of a microstructurally-based CDM model for forecasting creep properties.

Non-destructive Measurement of the Change of Micro Texture of Alloys Using Reflectance Spectrum Analysis of Visible lights

“…Figure 1(b) shows an example precipitate observed in Alloy 617. According to the EDX analysis of Martino et al (2) , mains precipitates in this alloy are M6C (M: mainly Mo, Ni) and M23C6 (M: mainly Cr, Mo). Figure 2 shows the reflectance spectrum obtained from each precipitate.…”

Stress Relief Cracking Susceptibility in High-Temperature Alloys

“…The stable phases reported for Inconel 617 were , M 6 C, MX, , and M 23 C 6 (Ref. 60). Both interand intra-granular Mo and Cr-rich second phases were observed from the XEDS scans (table in Fig.…”

The Effect of Long-Term Ageing on the Degradation of the Microstructure the Inconel 740h Alloy

“…Appropriate development directions are the modernization of existing units (mainly with the capacity of 200 MW created in the years 1960-1970) and construction of modern power units for over-and transient-critical parameters [5,6]. The most effective * corresponding author; e-mail: marek.sroka@polsl.pl way to improve efficiency and reduce harmful emissions for today's carbon-fueled blocks is to raise of thermodynamic parameters values of the water-steam circuit [7][8][9][10].…”