<p>The tensile and bending absorption energies, microstructural evolution, strain distribution, and crack behavior of U-notched samples of TRIP steel with multiscale retained austenite at different loading rates were investigated. For the tensile sample, it is demonstrated that the transformation amount of retained austenite to martensite before necking increases very slightly with decreasing loading rate. This provides a comparable transformation-induced plasticity effect, and thus leads to a similar absorption energy before necking at different loading rates. After necking, much retained austenite, especially at lower loading rates, has further transformed into martensite/austenite islands or martensite blocks, which provides a sustained high transformation-induced plasticity effect, and thus results in an increase in the absorption energy after necking and the total tensile absorption energy with decreasing loading rate. However, for the bending sample, much retained austenite in the high-strain region at U-notched bottom and crack tip, especially at lower loading rates, has transformed into martensite/austenite islands or martensite blocks, which provides a larger number of nucleation sites for crack initiation and paths for crack propagation, and thus decreases the crack initiation, crack propagation, and total bending absorption energies at lower loading rates.</p>