Self-healing Effect of Boron Nitride Precipitation on Creep Cavitation in Austenitic Stainless Steel

Abstract

In this study, the precipitation of boron nitride (BN) on creep cavity surfaces during creep and its beneficial effect on the creep rupture properties are reported for a type 304 austenitic stainless steel. In the conventional 304 stainless steel, the trace of soluble S segregates strongly on the creep cavity surfaces and promotes its growth during creep. In the modified 304 stainless steel added with B, Ce, and Ti, the trace of soluble S is removed effectively by the formation of Ce and Ti sulfides, and the segregation of S on the creep cavity surface is replaced by the precipitation of the BN compound. As BN is very stable at high temperatures, its precipitation on the cavity surface is expected to suppress the creep cavity growth rate. It is suggested that the precipitation of BN on the creep cavity surface provides austenitic stainless steel with the function of self-healing for creep cavitation with an associated increase in the creep rupture strength and ductility.

Improved Creep Behavior of a High Nitrogen Nb-Stabilized 15Cr-15Ni Austenitic Stainless Steel Strengthened by Multiple Nanoprecipitates

“…[10] The Al content (0.05 wt pct) is aimed at deoxidization during the melting process, and finally, boron addition (0.004 wt pct) is expected to improve creep rupture life by stabilizing grain boundary M 23 C 6 precipitates and by the self-healing effect of creep cavities through boron segregation at their surfaces. [11] III. EXPERIMENTAL PROCEDURE The 6.2 kg ingot of 15Cr-15Ni austenitic stainless steel was produced in a vacuum induction furnace under nitrogen pressure of about 0.95 atm.…”

Thermally activated precipitation at deformation-induced defects in Fe-Cu and Fe-Cu-B-N alloys studied by positron annihilation spectroscopy

“…[1][2][3] The precipitates partially fill the nanoscale open-volume defects and thereby prevent further growth. Self-healing is a promising new approach in the design of future steels with a longer component lifetime.…”

Dependence of Elevated Temperature Intergranular Cracking on Grain Size and Bulk Sulfur Content in TP347H Austenitic Stainless Steels

“…The ion-sputtering result supports that the elevated temperature intergranular cracking of the HS specimens is mainly due to the sulfur segregated at the austenite grain boundaries. [16][17][18][19] Figure 5 shows changes in time to failure and fracture mode with grain size and bulk sulfur content. As shown in Fig.…”