Oxide dispersion-strengthened steel PM2000 after dynamic plastic deformation: nanostructure and annealing behaviour

Abstract

The microstructure, texture and mechanical properties have been studied in PM2000 compressed via dynamic plastic deformation to a strain of 2.1. It is found that dynamic plastic deformation results in a duplex h111i ? h100i fibre texture and refines the initial microstructure by nanoscale lamellae, which substantially increases the strength of the material, but decreases its thermal stability. In the as-deformed microstructure, the stored energy density is found to be higher in h111i-oriented regions than in h100i-oriented regions. Recovery during annealing at 715°C reduces the energy stored in the deformed microstructure. This reduction is more pronounced in the h111i-oriented regions. Orientation-dependent recrystallisation takes place in the recovered microstructure, leading to strengthening of the h111i fibre texture component at the expense of the h100i fibre texture component.

Microstructural Analysis of Orientation-Dependent Recovery and Recrystallization in a Modified 9Cr-1Mo Steel Deformed by Compression at a High Strain Rate

“…Calculations based on the EBSD data show that the stored energy is significantly reduced during coarsening (see Figure 12), and that the reduction rate is higher in the h111i regions, for which the initial stored energy was greater than that for the h100i regions. This observation is in agreement with our recent results obtained on PM2000 annealed after DPD [4] and with findings obtained on commercial purity aluminum annealed after heavy rolling, [24] where more pronounced recovery was observed in high-energy texture bands compared to Figure 12), it is clear that the different reduction in the stored energy for the different regions is predominantly caused by differences in the loss of LABs.…”

“…For body-centered cubic (bcc) iron-based systems, the deformation texture after compression is dominated by h100i and h111i fiber texture components aligned with the compression axis (CA), and it is generally found that the h100i component weakens during recrystallization, whereas the h111i fiber texture strengthens significantly. [1][2][3][4] In a previous study [3] on a modified ferritic/martensitic 9Cr-1Mo steel where samples were deformed to a strain of 0.5 either by quasistatic compression (QSC) or by dynamic plastic deformation (DPD), [5,6] it has been found that DPD resulted in a stronger h111i + h100i fiber texture and in faster recrystallization than QSC. The faster recrystallization was attributed to a finer boundary spacing and, therefore, a higher energy stored during DPD as compared to QSC.…”

Heterogeneous microstructure and enhanced mechanical properties in annealed multilayered IF steel

“…During compression the texture changes, as crystal orientations rotate towards the stable components of the compression texture. Such stable components in bcc materials are known to be fibers with 111 and 100 parallel to the compression axis [28][29][30][31]. It should be noted that for the present sample, which was compressed along the ND of the rolled material, the  fiber of the rolling texture is coincident with the 111 fiber of the compression texture.…”

Quantifying yield behaviour in metals by X-ray nanotomography

“…The difference between the obtained and macroscopic yield stress is likely to be caused by material heterogeneity; the yield strength of PM2000 is grain size dependent 53 and the volume of material affected by the nanoindentation is significant relative to the grain size. Tensile data reported in other studies of bulk specimens of PM2000 steels 53 54 provide strain hardening exponents between 0.04 and 0.17.…”