Deforming Texture Effect on Phase Transformation in Stainless Steels

Abstract

In stainless steels during the non-equilibrium transformation of austenite the deformed bcc a' martensite and hexagonal, non-magnetic e martensite also can form. These transformations can be induced by cooling (under critical temperature) and/or mechanical deformation. The appearance of e martensite has an effect on the deformation ability and other properties. The experimental results associate the e martensite formation with the plastic deformation behaviour (TRIP effect), while the transformation of e martensite into a' martensite is accompanied with hardening. The present phases hardly determine the cold rolling properties. During the deforming of a', e, g phases in stainless steels the texture also developes. The initial strong deforming g texture changes with the appearance of a' martensite. We suppose that the transformation takes place at certain places in an anisotropic way due to the deforming texture. The texture of a' martensite develops by the initial anisotropy of parent phase and/or the phase deformation.

Deformation induced martensitic transformation in stainless steels

“…To describe the texture view of deformed samples a special inverse pole figure was used based on the X-ray diffraction data. This method-described in detail in an earlier paper [7]-is very useful for quantitative comparison of changing during deformation.…”

“…In these materials there is always a texture [6] due to the deformation that continuously changes owing to the thermomechanical treatments and the anisotrope transformation [7,8].…”

Effect of strain rate on stress-strain behavior of alloy 309 and 304L austenitic stainless steel

“…Since planar slip is integral to the transformation, the propensity for strain-induced martensite is not only a function of austenite stability but depends also on stacking fault energy (SFE), as proposed by Olson and Cohen. [1] Although it appears that the transformation may progress initially by the formation of a transitional epsilon phase, it has been shown [8,9,10] that as strain progresses, the transformation to epsilon stops and existing epsilon is completely consumed at relatively low levels of strain and that austenite transforms directly to martensite at higher levels of strain. Brooks et al [11,12] showed that martensite formed directly from dislocation pileups on {111} ␥ slip planes in low carbon austenitic stainless steels, including 304L, without a transitional phase.…”

Experimental and Numerical Investigations of the TRIP Effect in 1.4301 Austenitic Stainless Steel Under Static Loading

“…In the recent years, these steels have become a potential alternative for crash relevant steels for the automotive industry due to a very pronounced TRIP effect. Some of the austenitic stainless steels are metastable at room temperature and undergo martensitic transformation on being plastically deformed . The formation of martensite increases the work hardening rate resulting in high ultimate tensile strength and good uniform elongation .…”