Effect of adding yttrium on precipitation behaviors of inclusions in E690 ultra high strength offshore platform steel

Abstract

The mechanism of inclusions precipitation of the E690 offshore platform steel, with and without addition of yttrium, was studied using the thermodynamic calculation method. The results show that in the E690 steel in the absence of yttrium, the MnS inclusions were precipitated in the liquid phase at the solidification front. By adding the yttrium, MnS inclusions were replaced by spindle and spherical yttrium-containing oxide and sulfide complex inclusions, and the precipitation sequence of yttrium-containing inclusions in the liquid steel was Y2O3, Y2O2S, and YS. However, Y2S3 inclusions cannot be precipitated in the liquid steel under the experimental conditions. It was also found that Al2O3 inclusions can be formed in the liquid steel with and without addition of yttrium. The thermodynamic calculation results are in accordance with the experimental results.

Effect of Yttrium Addition on Nonmetallic Inclusions in FeCrAl Alloys

“…The interaction coefficients required are shown in Table 2 . [ 3,23–28 ] …”

“…In general steel grades, a desulfurization process is used to lower the sulfur level to tens of ppm during the refining process, so the sulfide generated is usually YS inclusions after Y addition. Xi et al [ 23 ] investigated inclusions modified by Y in E690 steel and found that the generated inclusions were Y 2 O 3 , Y 2 O 2 S, and YS, while Y 2 S 3 did not form in the steel. Chen et al [ 9 ] reported that Y 2 O 3 and Y 2 O 2 S inclusions precipitated when the Y content in E36 steel was low and that YS inclusions formed when the Y content further increased.…”

“…The w [O] -w [S] -w [Y] three-dimensional stable phase diagram based on the change in mass fraction at 1,873 K was drawn using MATLAB software with MeshGrid, Isosurface, and Contour functions employed. According to the superposition of Equation ( 1) and ( 4), [23] the reaction formula of Equation ( 5) can be derived. The reaction formulas of inclusions and the standard Gibbs free energy are listed, as shown in Equation ( 5)- (8).…”

Correlation Between Nonmetallic Inclusions and Localized Corrosion of a Low‐Nickel Stainless Steel with Cerium Treatment

“…In recent years, with the increasing demand for high-quality stainless steels, rare earth (RE) elements have attracted the attention of scholars due to their significant influence on the steel. [1][2][3][4][5][6][7][8] Inclusions in the steel, which have an important impact on the performance of the steel, [9][10][11][12] could be effectively modified by RE due to its strong affinity to oxygen and sulfur, [13][14][15][16][17][18] thus, influencing the property of the steel. Wang et al [19] found that an appropriate addition of RE reduced the susceptibility of pitting corrosion and improved the corrosion resistance of a duplex stainless steel.…”