Effect of Nitrogen on Deformation-Induced Martensitic Transformation in an Austenitic 301 Stainless Steels

Abstract

Abstract:The effect of nitrogen on deformation-induced martensitic transformation (DIMT) in metastable 301 austenitic stainless steel has been studied based on the inelastic deformation theory. DIMT is regarded here as continuous relaxation process of internal strain energy accumulated during inelastic deformation. Using the kinetics equation based on the inelastic deformation theory the relationship between the volume fraction of transformed martensite and inelastic strain for DIMT has been successfully verified with the parameter representing the stability of austenite. The addition of nitrogen is experimentally found to increase austenite stability and the critical inelastic strain below which any DIMT is not observed to occur and to decrease the saturation volume fraction of α' martensite. On the other hand, DIMT has been analyzed with its effect on stress-strain curve shape and mechanical properties in relation to the addition of nitrogen. The characteristic transition from sigmoidal to parabolic curve shape in stress-strain response has disappeared with the addition of nitrogen.

Deformation-induced martensite in austenitic stainless steels: A review

“…Compared to Fig. 9a, the capability of this model seems to be better due to the incorporation of additional parameters [151,172]. For the non-pre-strained and pre-strained ASSs with initial α′-martensite content, modified Olson-Cohen models have been proposed [152].…”

Stress or strain induced martensitic and bainitic transformations during ausforming processes

“…where and are the shear and dilatational strains associated with the martensitic or bainitic transformation and is the stress that is being applied in The stress must be set as the austenite yield strength at any given temperature to consider the limit scenario for martensite or bainite stress induced transformations. The experimental values cannot be used to find an expression that describes the σ Y evolution with temperature because, as stress-strain curves representative of stress induced transformations are characterized by a transition from parabolic to sigmoidal as transformations progresses [8][9][10][11], such transformations would lower σ Y and would make the calculation invalid. For that reason, the latest developed model [77] has been used to predict σ Y as a function of deformation temperature Tdef and strain rate ε: where X i is the solute content of the element i in at.…”

“…As the application of deformation can alter the temperatures at which transformations start, martensite, bainite or even ferrite can form at temperatures at which they usually do not appear [8][9][10][11][12][13][14][15][16]. Although stress and strain induced martensitic transformations were discovered almost one century ago by Scheil [17], they have been mainly studied in alloys in which austenite is stable at room temperature until stresses or strains are applied to it, see for example the works performed on iron-nickel alloys or austenitic steels in references [17][18][19][20][21][22][23][24][25][26][27].…”

Evolution of Microstructure and Hardness of High Carbon Steel under Different Compressive Strain Rates

“…; RA transforms to strain induced α and ε martensite [5]. The consequence of this transformation is dependent on various parameters, such as morphology [6], chemical composition [1,6,7] and stacking fault energy of austenite [8]. The α martensite is found to be nucleated at the intersection of the shear bands, while the ε-martensites are formed due to the overlapping stacking faults [8].…”