The Investigation of Strain-Induced Martensite Reverse Transformation in AISI 304 Austenitic Stainless Steel

Abstract

This paper presents a comprehensive study on the strain-induced martensitic transformation and reversion transformation of the strain-induced martensite in AISI 304 stainless steel using a number of complementary techniques such as dilatometry, calorimetry, magnetometry, and in-situ X-ray diffraction, coupled with high-resolution microstructural transmission Kikuchi diffraction analysis. Tensile deformation was applied at temperatures between room temperature and 213 K (À60°C) in order to obtain a different volume fraction of strain-induced martensite (up to~70 pct). The volume fraction of the strain-induced martensite, measured by the magnetometric method, was correlated with the total elongation, hardness, and linear thermal expansion coefficient. The thermal expansion coefficient, as well as the hardness of the strain-induced martensitic phase was evaluated. The in-situ thermal treatment experiments showed unusual changes in the kinetics of the reverse transformation (a¢ fi c). The X-ray diffraction analysis revealed that the reverse transformation may be stress assisted-strains inherited from the martensitic transformation may increase its kinetics at the lower annealing temperature range. More importantly, the transmission Kikuchi diffraction measurements showed that the reverse transformation of the strain-induced martensite proceeds through a displacive, diffusionless mechanism, maintaining the Kurdjumov-Sachs crystallographic relationship between the martensite and the reverted austenite. This finding is in contradiction to the results reported by other researchers for a similar alloy composition.

Metal‐Matrix Materials for High‐Temperature Applications with Liquid Aluminum

“…The rest was α'‐martensite and δ‐ferrite, which cannot be reliably distinguished due to their common bcc crystal structure. The phase composition of similar steel specimens usually alters during the thermal treatment of such powder metallurgically manufactured specimens as a result of the retransformation of martensite into austenite and/or intensive diffusional interactions between the metal and the ceramic component during sintering . The ferromagnetic fraction (martensite and ferrite) of the pure steel material was roughly 29% according to MSAT measurements.…”

Deformation-induced martensite in austenitic stainless steels: A review

“…10 Estimation of the different hardening effects in the cold rolled AISI 304L stainless steel [186] Fig . 11 a Effect of room temperature rolling on the tensile properties of AISI 304 stainless steel [184], b Effect of cold rolling and cold rolling + tension on the martensite content of AISI 304 stainless steel [184], and c-e T ensile stress-strain curves, work-hardening plots, and total elongation of AISI 304 stainless steel at different temperatures [190] Archives of Civil and Mechanical Engineering least partly) from the increase in the amount of martensite. Figure 11b also reveals that the tensile deformation, itself, results in the martensitic transformation, which might contribute to the tensile strength and ductility of the alloy [184].…”

Thermal Stability of Rolled Metastable Austenitic Stainless Steel 1.4307 Studied Using Positron Annihilation

“…Cios et al showed that the completely recrystallized material does not contain DIM. [22] An increase in the S parameter at 475°C coincides with the small maximum of microhardness for samples A and B with a higher amount of a¢-martensite. The increase in microhardness may be caused by precipitation of carbides.…”

“…PAS measurements were carried out using the 22 Na positron source encapsulated in 7-lm-thick Kapton foil. The DB of the 511 keV annihilation line was measured using a coaxial high-purity germanium (HPGe) detector with a 1.4 keV energy resolution at the full width at half maximum (FWHM) interpolated at 511 keV.…”