Effect of Y2O3 and ZrO2 on the microstructure and mechanical properties of nano-ODS 21Cr-9Mn-6Ni steels

Abstract

In this article, nano-oxide dispersion-strengthened (ODS) 21Cr-9Mn-6Ni steels were prepared from elemental powders through vacuum hot pressing. Three ODS steels (21Cr-9Mn-6Ni-0.4Ti-0.3Y2O3, 21Cr-9Mn-6Ni-0.4Ti-0.3ZrO2 and 21Cr-9Mn-6Ni-0.4Ti-0.15Y2O3-0.15ZrO2) were prepared to study the effect of Y2O3 and ZrO2 additions on the microstructure and mechanical properties. The nano-oxide precipitates within the austenite matrix were identified using a transmission-electron microscope equipped with energy-dispersive X-ray spectrometer (TEM-EDX). An addition of Y2O3 with ZrO2 leads to the formation of a bimodal distribution of grains and fine oxide particles of Y-Zr-O and Y-Ti-O in the microstructure of an ODS steel. The results of the tensile test at different temperatures reveal that the strength and elongation of 21Cr-9Mn-6Ni steels are improved with the addition of Y2O3 and ZrO2 due to a stronger interface bonding between large numbers of oxide particles and the austenite matrix.V~lanku avtorji opisujejo izdelavo z nano-oksidnimi delci disperzijsko utrjenega (ODS) jekla 21Cr-9Mn-6Ni. ODS jeklo je bilo izdelano z vro~im stiskanjem iz elementarnih prahov. Tri ODS jekla (21Cr-9Mn-6Ni-0,4Ti-0,3Y2O3, 21Cr-9Mn-6Ni-0,4Ti-0,3ZrO2 in 21Cr-9Mn-6Ni-0,4Ti-0,15Y2O3-0,15ZrO2) so izdelali z namenom, da bi raziskali vpliv dodatkov Y2O3 in ZrO2 na mikrostrukturo in mehanske lastnosti. Nano-oksidne izlo~ke v austenitu so okarakterizirali s presevnim elektronskim mikroskopom, opremljenim z rentgenskim energijskim disperzijskim spektrometrom (TEM-EDX). Ugotovili so, da dodatek Y2O3 s ZrO2 vodi do tvorbe bimodalne porazdelitve kristalnih zrn in drobnih oksidnih delcev Y-Zr-O in Y-Ti-O v mikrostrukturi ODS jekla. Natezni preizkusi pri razli~nih temperaturah so pokazali, da sta se trdnost in raztezek 21Cr-9Mn-6Ni jekla izbolj{ala z dodatkom Y2O3 in ZrO2 zaradi mo~nej{e vezi med velikim {tevilom oksidnih delcev in austenitno matrico.

The Effect of the Chemical Composition to the End-Properties of Ceramic Dispersed Strengthened 316L/Y2O3 Composites

“…Hutař et al [16] studied the small fatigue crack propagation in Y 2 O 3 strengthened steels and they found that yttria content has no significant effect to the crack propagation. Kumar et al [17] studied the effect of Y 2 O 3 and ZrO 2 on the microstructure and mechanical properties of nano-ODS (oxide dispersion strengthened steel) where it was found that the hot pressed Y 2 O 3 containing ODS steels show higher ultimate tensile strength (UTS) comparing to the ZrO 2 containing ODS and it shows even higher UTS values when compared with ZrO 2 . The yttria content under 0.6wt% improves the oxidation resistance by forming a stable oxide scale and improving the adhesion, while higher amounts of yttria results in segregation of this last, The yttria addition tends to decrease the bending strength and the hardness of the steel [18].…”