Relevance of Other Parameters than Carbon Activity in Defining the Severity of a Metal Dusting Environment

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 18115To link to this article:To cite this version: Rouaix -Vande Put, Aurélie and Fabas, Aurélien and Doublet, Sébastien and Monceau, Daniel Relevance of other parameters than carbon activity in defining the severity of a metal dusting environmentAbstract Two metal dusting experiments were carried out at 570°C on 800HT and HR120 alloys, for more than 6000 h. The tests were designed to run at different total pressures and gas velocities but similar carbon activities and oxygen partial pressures. For a given alloy, shorter average incubation times and larger mass losses were observed at high pressure. For both tests, HR120 alloy underwent greater mass losses and exhibited a higher pit density. For nearly all samples, pit densities greatly differed between both sides of the specimens. Therefore, the carbon and oxygen activities alone are not sufficient to evaluate the aggressiveness of a metal dusting environment. Greater degradation was the result of the association of a higher gas velocity with a higher total pressure and a finer alloy grain size.

An Expanded Model for the Pressure Effect in Metal Dusting of Mn-Containing Alloy 600 Based on Advanced Scale Characterization

“…Additionally, they showed that if the gas composition remains the same, a higher pressure accelerates the attack. Both phenomena were confirmed to be generally valid for other alloys in the more current works of Madloch [7] and Rouaix-Vande Put [8], as well as Levi and Briggs [9]. An intuitive explanation to the above results may be offered by Le Chatelier's principle [10], where gases under pressure have a higher tendency to form solid reaction products, such as C. Additionally, the C activity is increased when a 1 3…”

“…High Temperature Corrosion of Materials (2023) 100:541-555 gas is pressurized. However, the parameter "total pressure" is not really understood for MD and Le Chatelier's principle, and activity is not sufficient to explain the reduced resistance of the oxide scale, as observed from shorter incubation times [8,11]. Fundamental work was reported by Natesan and co-workers, who related the occurrence of MD to spinel oxide formation in the scale [12][13][14].…”

Influence of sample thickness and microstructure on metal dusting behavior of NiCrFeAl alloys

“…Such a variation of pit density between the front and back of a sample is not a new effect. It has been reported previously in literature, that is, in Rouaix-Vande Put et al [49] There, a higher gas velocity at the sides with the higher pit density was identified as the cause. For a variation in pit density between front and back of a sample, we see three potential causes:…”

“…Such a variation of pit density between the front and back of a sample is not a new effect. It has been reported previously in literature, that is, in Rouaix‐Vande Put et al [ 49 ] There, a higher gas velocity at the sides with the higher pit density was identified as the cause. For a variation in pit density between front and back of a sample, we see three potential causes: The surface facing the outside of the furnace tube may experience a different gas composition than the surface facing the center of the furnace tube. The gas velocity The microstructure is different on both surfaces…”

“…This is relatively large for laboratory exposure in metal dusting atmospheres compared to some previous metal dusting experiments, that is, 400 mm 2 (10 × 20 × 1 mm 3 ) in the study by Grabke et al [10,11] or 480 mm 2 (sample 12 × 20 × 1 to 2 mm 3 ) in the study by Natesan and Zeng. [36] Furthermore, there are samples sizes with an area of 296 mm 2 (7 × 14 × 1.5 mm 3 ) in the study by Zhang and Young, [21,43] about 308 mm² (∅ 14 × 1.6 mm 3 ) in the study by Rouaix-Vande Put et al [49] or 300 mm 2 (15 × 10 × 5 mm 3 ) in the study by Madloch et al [50] Table 3 shows an overview of the sample codes, the thicknesses and grain sizes. T01 and T04 have the same production and preparation history as the samples 150A-2 and 152A-2 in.…”