Strain induced martensite formation and its effect on strain hardening behavior in the cold drawn 304 austenitic stainless steels

Formability evaluation of two austenitic stainless steels

“…The transformation observed between 100 o C and 300 o C is the reversion of ε martensite, formed in small quantities. The transformation observed between 500 o C and 700 o C is the α'→γ transformation (Gonzalez et al, 2003). This transformation is more evident in steel A indicating, in a semi quantitative way, larger amounts of α' martensite in this steel.…”

“…Differences between the Erichsen Index values can be explained by the differences in α' martensite contents when the materials are submitted to stress and strains of tensile nature (biaxial tension). According to Gonzalez et al (2003), when the martensitic transformation occurs in optimized quantities, larger uniform elongations are attained. In other words, the better the optimized rates of α' martensite formation the better will be the performance of the material when submitted to biaxial tension.…”

“…The amount of deformation induced α' martensite was determined by magnetic measurements, using a ferrite detector. The calibration of the ferrite detector was performed by comparative measurements made in a magnetic saturation balance (Choi et al, 1997). The magnetic measurements were performed with the ferrite detector at different positions of the tension test specimens, in order to verify the homogeneity of formation of α' martensite along the specimens.…”

“…A considerable increase of the mechanical resistance is attained when these steels are deformed at temperatures under M d , the temperature below which the formation of stress induced α' martensite occurs. This increase of the material plasticity caused by martensite formation is known as TRIP effect -Transformation Induced Plasticity - (Rintamaa et al, 1982, Choi et al, 1997. The transformation of the austenite (face centered cubic, paramagnetic phase) to ε martensite (hexagonal compact, paramagnetic phase) or to α' martensite (body centered tetragonal, ferromagnetic phase) depends on the chemical composition of the alloy, on the temperature and on the amount of deformation.…”

Experimental research on the effect of the ball burnishing process, using new kinematical scheme on hardness and phase composition of surface layer of AISI 304L stainless steel

“…The formation and the amount of strain-induced martensite depends on the austenite stability (the chemical composition and the initial austenite grain size) and the strain hardening conditions (the deformation temperature, strain and strain rate) [6,7].…”