Analysis of the Trip Effect by Means of Axisymmetric Compressive Tests on a Si-Mn Bearing Steel

摘要

Analysis of the TRIP-effect has been implemented by means of series of axisymmetric compressive tests on a Si-Mn bearing TRIP-assisted steel heat treated to vary the amount of retained austenite from 5.70 to 9.11 percent. The cylindrical samples were deformed with true strains of 0.25, 0.5 and 1, and constant strain rate of 0.1 s~(-1) at room temperature. Microstructural examination of the samples indicates that most of the deformation is sustained by the weakest phase, ferrite. The stress-strain data was fitted to different constitutive equations to evaluate the point at which the TRIP-effect triggers. The results showed that the amount of retained austenite is reduced with the increase of strain. No complete transformation of austenite was found to occur as a fraction of austenite remains untransformed even at equivalent strains as high as one. The behaviour of samples with different amounts of retained austenite, but of equal carbon content, was found to depend on the volume fraction of this structure. It was found that the TRIP-effect was triggered at lower strains, but higher stresses, as the amount of this phase increased.