Abstract: The microstructure and mechanical properties for low silicon transformationinduced plasticity (TRIP) steels with phosphorus addition under different annealing conditions were investigated in laboratory. The addition of low price element phosphorus reduced the silicon content which improved surface qualityand solved galvanizing problem with lowercosts. The results showed that the tensile strength increased with the increase of the annealing time， the tendency of the amount of the retained austenite first increased and then decreased at both intercritical temperatures. The largest amount of the retained austenite was 22% at the constant temperature of 780℃ for 180s while 20% at the constant temperature of 800℃ for 90s. The steels had excellent mechanical properties with the product of the tensile strength and elongation of 22854MPa·% when annealing at constant temperature of 780℃ for 180s. No mechanical property loss were caused by the phosphorus addition and the mechanical properties of the low silicon TRIP steels were excellent.

Key words: TRIP(transformationinduced plasticity) steel, intercritical annealing, phosphorus addition, low silicon, microstructure and mechanical properties