Tensile Deformation Induced Texture Transformation in Austenitic Stainless Steel

S Grigull

doi:10.1080/07303300310001628616

Abstract

Texture patterns of the starting ώ and transformed α structural phases were obtained from AISI 304 stainless steel sheets subjected to varying levels of tensile deformation using high energy X-ray diffraction in combination with the texture enhanced Rietveld method. The use of this method allows the simultaneous determination of the orientation distribution functions (ODF) of both phases, even for small α-martensite fractions of the order of 5%. The texture patterns are analyzed in terms of the crystallographic orientation relation between the starting and transformed phases and the preferential formation of certain variants of this relation.

Highlights

Due to its enormous practical importance the deformation induced – transformation in ferrous alloys has been studied for more than 50 years, and numerous experimental and theoretical studies have been reported focusing on the transformation mechanism (Patel and Cohen, 1953; Angel, 1954; Bogers and Burgers, 1964, Olson and Cohen, 1975; Furubayashi, 1985)
The strain induced texture transformation from the fcc phase to the bcc phase in metastable austenitic stainless steel has been studied on sheet samples exposed to uniaxial tension applied along the rolling direction
The transformation can be qualitatively described by the Kurdjumov–Sachs orientation relation

Summary

INTRODUCTION

Due to its enormous practical importance the deformation induced – transformation in ferrous alloys has been studied for more than 50 years, and numerous experimental and theoretical studies have been reported focusing on the transformation mechanism (Patel and Cohen, 1953; Angel, 1954; Bogers and Burgers, 1964, Olson and Cohen, 1975; Furubayashi, 1985). Ð1Þ often associated with the – transformation in ferrous alloys with low stacking fault energy such as stainless steel allows 24 symmetry equivalent orientation variants in the transformation product to be formed from each parent crystallite orientation. These 24 variants are never observed to occur all together in the martensite phase. The second criterion is based on the shear transformation model proposed by Bogers and Burgers (1964) This criterion assumes that those variants form for which shear in the two {111}h211i twin systems of the fcc lattice involved in the transformation is aided to a maximum degree by the deformation strain (Higo et al, 1974). The combination of these techniques is used to fill part of the gap in existing texture data on the – transformation in uniaxially stretched austenite, with the focus on the effect of orientation variant selection on the martensite texture pattern

EXPERIMENT AND DATA PROCESSING

RESULTS AND DISCUSSION

CONCLUSIONS