Influence of elastic and plastic anisotropy on the flow behavior in a duplex stainless steel

Abstract

The load partitioning between two phases in a cold-rolled duplex stainless steel has been experimentally studied in situ by X-ray diffraction, for different loading directions. It was found that the load partitioning between the two phases is dependent on the loading direction. For loading in the rolling direction, both phases deform plastically to the same degree, while more plastic deformation occurs in the austenitic phase during loading in the transverse direction. For loading in the 45-deg direction, more plastic deformation occurs in the ferritic phase. The strong crystallographic texture in the ferritic phase makes the material anisotropic, with a higher stiffness and yield strength in the transverse direction compared to the rolling direction. The measured texture was used as input to theoretical predictions of both elastic and plastic anisotropy. The plastic anisotropy was predicted by assuming intragranular slip as the main deformation mechanism. The predicted anisotropic material properties were then used in finite-element simulations to study the flow behavior of the material in different directions. The predicted flow behavior was found to be in good agreement with the experimentally observed load partitioning between the phases for loading in the rolling and transverse directions. However, the yield strength of the ferritic phase during loading in the 45-deg direction was found to be lower than what was predicted. The reason for this is the difference in slip characteristics in different sample directions, because of the morphological texture.

Texture and Planar Anisotropy of <I>r</I>-Value in Duplex Stainless Steel Sheet

“…The features of a strong bcc -fiber (f100gh011i-f211gh011i-f111gh011i) and an undevelopedfiber (f111gh011i-f111gh112i) in the final annealed sheets are similar to the previous studies. [4][5][6][7][8][9][10] The orientation density increased with increasing cold-rolling reduction. The main orientation is f100gh011i at a 67% cold-rolling reduction, while it is f211gh011i at 78% and 89% cold-rolling reductions.…”

“…As both the and phases are elongated along the longitudinal direction unlike single-phase materials, a shape factor of the phase or grain boundaries should be considered for DSS sheets. From the viewpoint of the morphological contribution, Moverare et al 8) presented that for loading at the 45 direction, the Texture and Planar Anisotropy of r-Value in Duplex Stainless Steel Sheetdirection of maximum shear stress was oriented to the same direction as the elongated microstructure and the slip lines extended over a greater distance compared with loading at the rolling and transverse directions. Further investigations in consideration of the morphology and observations of the deformation structure are required in future to realize the precise prediction of plastic anisotropy in DSS sheets.…”

“…It has been shown that the yield point and elongation of DSS cold-rolled and annealed sheets depend on the texture of the matrix with the strong -fiber (f100gh011i $ f111gh011i) i.e., cold-rolling texture for BCC metal. [4][5][6][7][8][9][10][11][12][13] However, there are few studies on the planar anisotropy of the r-value and the effect of the texture of each phase on the r-value. 7,8) In this study, the texture and the planar anisotropy of the r-value were investigated for type 329J4L DSS sheets with different cold-rolling reductions.…”

“…[4][5][6][7][8][9][10][11][12][13] However, there are few studies on the planar anisotropy of the r-value and the effect of the texture of each phase on the r-value. 7,8) In this study, the texture and the planar anisotropy of the r-value were investigated for type 329J4L DSS sheets with different cold-rolling reductions. Additionally, we predicted the planar anisotropy of the r-value on the basis of the Taylor theory from the quantitative texture of each phase, and then the most suitable model for predicting the plastic anisotropy of DSS sheet was also examined by comparison with experimental data.…”

Texture and Planar Anisotropy in Lean Duplex Stainless Steel Sheet

“…[7][8][9][10] When materials are applied to sheet products, sheet formability and anisotropy in addition to strength and elongation are important, and there are few reports about the formability of standard DSS sheets. [11][12][13][14][15][16] According to these findings, it has been reported that high-alloy DSS sheets have a large planar anisotropy and their texture is different from that of single-phase materials, [11][12][13][14][15][16] but studies on the texture and planar anisotropy of the lean DSS sheets are not found.…”