Some Strengthening Methods for Austenitic Stainless Steels

Abstract

Austenitic stainless steels possessing good corrosion resistance have recently found growing applications as a constructional material. In this instance, increasing strength properties, which are typically quite low, is of great interest. Due to the low stacking fault energy, strain hardening of alloyed austenite is efficient for increasing tensile strength without impairing ductility seriously. In addition, certain grades are unstable, so that cold working creates strain‐induced martensite that enhances strengthening. Grain size refinement to micrometer scale or even finer can also increase the yield strength, still providing good ductility. In the present paper dislocation and phase transformation strengthening and thereby properties achievable in temper rolled austenitic stainless steels are discussed. Strengthening by the reversion annealing is also described and excellent results achievable are shown. Finally, the effect of bake hardening through the static strain ageing is presented. Long‐term research work in various projects indicates that the current knowledge of strengthening of austenitic stainless steels is close to the industrial utilisation.

Effects of deformation-induced martensite and grain size on ductile-to-brittle transition behavior of austenitic 18Cr-10Mn-N stainless steels

“…For a detailed microstructural analysis, a specific region beneath the fracture surface showing a bcc structure in the EBSD micrograph was prepared by a focusedion beam technique and then examined using TEM. The bright-field TEM image confirmed that α'-martensite was present mostly at the intersection area of deformation shear bands and had a Kurdjumov-Sachs (K-S) orientation relation with austenite [11][12][13]16] (Fig. 4(c)).…”

“…The chemical composition, nitrogen pressure, and M d30 temperature of the austenitic 18Cr-10Mn-N stainless steels fabricated in the present study are listed in Table 1. The M d30 temperature is widely used as a quantitative criterion to estimate austenite stability and is inversely related to austenite stability [11,12]. Thus, the 4Ni-3Mo-0.54N steel has higher austenite stability due to the addition of Ni and Mo, compared to the other steels.…”

“…Since temperature and alloying elements including N exert significant influence on austenite stability against deformation-induced martensite transformation (DIMT) [10][11][12][13], the effect of deformation-induced martensite on the ductile-tobrittle transition behavior should be carefully taken into account in terms of achieving low-temperature toughness. In particular, the DIMT can affect the toughness and DBTT of austenitic Cr-Mn-N stainless steels with lean chemistry, i.e.…”

Influence of laser cutting on the fatigue limit of two high strength steels*

“…In the annealed state, their totally austenitic microstructure confers them an excellent ductility although limited yield stress. Cold deformation generates strain-induced martensite which, in addition to austenite strain hardening, results in a drastic improvement of yield stress [5] besides an excellent formability.…”

Effect of Nb Microalloying on Reversion and Grain Growth in a High-Mn 204Cu Austenitic Stainless Steel

“…Anna KISKO, 1) * Juho TALONEN, 2) David Arthur PORTER 1) and Leo Pentti KARJALAINEN (Received on March 24, 2015; accepted on June 17, 2015) Highly refined grain size can be obtained in metastable austenitic stainless steels by martensitic reversion treatment, but the annealing must be controlled due to the high coarsening tendency of ultrafine grains. The effect of Nb microalloying on reversion and retardation of grain growth has been investigated in an austenitic 204Cu stainless steel containing Nb from 0 to 0.45 wt.%.…”