Deformation twinning in AISI 316L austenitic stainless steel: Role of strain and strain path

Abstract

AISI 316L austenitic stainless steel was deformed at different strain and strain paths. The twin boundaries in the deformed microstructure had two possible origins: decay of original annealing twins and generation of deformation twins. Assuming that rotations of grains, specifically grains on both sides of a twin boundary, are responsible for the twin decay, a simple model was proposed to bring out the domain of relative twin generation. A biaxial strain path, in general, was associated with strong twin generation -an association or dependency linked to the texture estimated values of Taylor factor. Formation of strain induced martensite was also observed to be strain and strain path dependent and was more in biaxial strain path.

Improved predictability of forming limit curves through microstructural inputs

“…These were confirmed by X-ray diffraction (valid for higher martensite percentages) and VSM (vibrating sample magnetometer)[34].…”

“…This was attempted using both constant and varying r and n. A few interesting past studies can be cited [31][32], where varying r and n (from actual mechanical test data) were used successfully for improved FLC predictions. Past studies [34][35][36] have also shown a strong correlation between microstructure with strain and strain path. However, what makes the present study interesting is that it could convert tangible aspects of microstructural developments (e.g.…”

“…However, improvements in FLC predictability may also be obtained by incorporating varying r in 316L and 304L. Austenitic stainless steels can have significant twinning [34] and strain induced martensite formations [35][36][37][38] and therefore there is no simple procedure to estimate r from microstructure and crystallographic texture and this is not in the scope of the present work.…”

“…It may be noted that the selected metals have a range of material properties 1 and were observed (and are expected) [31][32][33][34][35][36][37][38] to have remarkably different microstructural developments. Some earlier studies [31][32] have already shown improvement in FLC prediction by using materials model which takes into account changes in material properties during deformation.…”

Deformed microstructures of two-phase Zr–2.5Nb alloy: Effects of the second phase hardness

“…This can be explained in terms of larger grain size and/ or presence of softer second phase. Larger grain size is expected [48][49][50] to promote deformation twinning, though recent studies on twinning in single phase Zircaloy 2 [46,47] showed that f1 0 1 2gh1 0 1 1i tensile twins are affected more by crystallographic orientation than by moderate (similar as in the case of the present study) differences in-grain size. Twinning is also expected if slip is restricted [47,51,52].…”