Analysis of deformation induced martensitic transformation in stainless steels

Abstract

Many studies monitoring the formation of martensite during the tensile deformation of austenite report data which are, in principle, affected by both the applied stress and the resulting plastic strain. It is not clear in these circumstances whether the transformation is stress induced (i.e. the stress provides a mechanical driving force) or whether the generation of defects during deformation helps nucleate martensite in a scenario better described as strain induced transformation. The authors demonstrate in the present work that a large amount of published data relating the fraction of martensite to plastic strain can in fact be described in terms of the pure thermodynamic effect of applied stress.

Changes in the mechanical properties and microstructure of anisotropic austenitic stainless sheet steel after uniaxial tensile test

“…Many research teams [1,2] are dealing with the problem of the unequal deformation of sheet metal materials during the technological process of manufacturing of different parts. One of the aspects in turns of cold plastic deformation is the unequal thickness reduction during the complex loading schemes that leads to earlier destruction of the material.…”

More Complete Theory for the Calculation of the Martensite–Start Temperature in Steels

“…We have assumed, with some justification, [15][16][17][18][19][20][21] that all of the changes in MS during uniaxial deformation can be explained solely in terms of stress, stabilisation and austenite grain refinement. In the theory of strain-induced martensite 42) plastic strain influences the progress of transformation by introducing nucleation sites, but as pointed out, this does not seem to represent a large effect.…”

“…The well-known nucleation of martensite at slip-bands and twin intersections naturally cannot be neglected so it is premature to conclude that strain-induced effects are always small. But it remains the case that when stress and strain are implemented simultaneously, [15][16][17][18][19][20][21] the observations can be rationalised largely on the basis of the mechanical driving force.…”

“…Several recent studies support this contention, that so-called strain-induced martensite in studies where stress and strain have been applied simultaneously, can be explained on the basis of stress alone. [16][17][18][19][20][21] Indeed, transformation textures for displacive products can often be explained on the basis of variant selection due to stress alone. 22) There have been limited experiments in which the effect of strain alone was studied.…”

Analysis of ferrite formed in 321 grade austenitic stainless steel

“…The formation of α' is usually associated with deformation and it is known that martensite can form in the 300 series of stainless steel during deformation at temperatures well above the marteniste start temperature [4][5][6][7]. This effect can be induced by deformation and also by cooling to a low temperature (-195°C) [8,9].…”