The effect of rare-earth cerium on impurity P-induced embrittlement for an advanced SA508Gr.4N reactor pressure vessels steel is investigated by virtue of microstructural characterization, Auger electron spectroscopy (AES), and spin-polarized density functional theory (DFT) calculations. The ductile-to-brittle transition temperatures (DBTTs) are evaluated by Charpy impact testing, and grain boundary segregation (GBS) of P is quantified by AES. Trace addition of Ce can effectively reduce GBS level of P, thereby substantially decreasing the embrittlement induced by P. A linear correlation between DBTT (°C) and GBS level of P (Cp, at.%) is observed for both undoped and Ce-doped samples, being expressed as <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42243_2025_1460_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="192" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{DBTT}} = 13.{13}C_{{\text{p}}}^{{}} - 33{5}{\text{.70}}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>DBTT</mtext> <mo>=</mo> <mn>13.13</mn> <mmultiscripts> <mi>C</mi> <mrow> <mtext>p</mtext> </mrow> <mrow /> </mmultiscripts> <mo>-</mo> <mn>335</mn> <mtext>.70</mtext> </mrow> </math></EquationSource> </InlineEquation> (undoped) and <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42243_2025_1460_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="191" /> </InlineMediaObject> <EquationSource Format="TEX">${\text{DBTT}} = 12.{67}C_{{\text{p}}}^{{}} - 350.{78}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mtext>DBTT</mtext> <mo>=</mo> <mn>12.67</mn> <mmultiscripts> <mi>C</mi> <mrow> <mtext>p</mtext> </mrow> <mrow /> </mmultiscripts> <mo>-</mo> <mn>350.78</mn> </mrow> </math></EquationSource> </InlineEquation> (Ce-doped). In the absence of GBS of P, the incorporation of Ce appears to play a pivotal role in augmenting the intrinsic toughness. These results imply that the impact of Ce on impurity P-induced embrittlement may be attributed to a combination of increasing the intrinsic toughness and lowering GBS of P. DFT calculations indicate that there is a negligible interaction between Ce and P in the ternary alloy, and thus GBS of P and Ce is mainly site-competitive.

Phosphorus-caused embrittlement of SA508Gr.4N reactor pressure vessel steel and its suppression by rare-earth cerium

期刊论文
发表日期：

2025年3月18日

查看全文

Yu Guo,
Kai Wang,
Wen-shuai Liu,
Xiao-ping Zhu

摘要

The effect of rare-earth cerium on impurity P-induced embrittlement for an advanced SA508Gr.4N reactor pressure vessels steel is investigated by virtue of microstructural characterization, Auger electron spectroscopy (AES), and spin-polarized density functional theory (DFT) calculations. The ductile-to-brittle transition temperatures (DBTTs) are evaluated by Charpy impact testing, and grain boundary segregation (GBS) of P is quantified by AES. Trace addition of Ce can effectively reduce GBS level of P, thereby substantially decreasing the embrittlement induced by P. A linear correlation between DBTT (°C) and GBS level of P (C_p, at.%) is observed for both undoped and Ce-doped samples, being expressed as ${\text{DBTT}} = 13.{13}C_{{\text{p}}}^{{}} - 33{5}{\text{.70}}$ $DBTT = 13.13 C_{p} - 335 .70$ (undoped) and ${\text{DBTT}} = 12.{67}C_{{\text{p}}}^{{}} - 350.{78}$ $DBTT = 12.67 C_{p} - 350.78$ (Ce-doped). In the absence of GBS of P, the incorporation of Ce appears to play a pivotal role in augmenting the intrinsic toughness. These results imply that the impact of Ce on impurity P-induced embrittlement may be attributed to a combination of increasing the intrinsic toughness and lowering GBS of P. DFT calculations indicate that there is a negligible interaction between Ce and P in the ternary alloy, and thus GBS of P and Ce is mainly site-competitive.