Quench Sensitivity of AA7N01 Alloy Used for High-Speed Train Body Structure

摘要

The quench sensitivity of AA7N01 aluminum alloy used for high-speed train body structure was investigated by end-quenching test, time-temperature-transformation curves simulation, transmission electron microscopy and scanning transmission electron microscopy. The hardness decreased with the increasing distance from the quenched end, and the depth of the age hardening layer was about 50mm. The simulation results showed that the high quench sensitivity temperature was between 230 degrees C and 300 degrees C and the critical cooling rate should be larger than 2 degrees C/s. The decrease of hardness along the increasing distance from the quenched end was attributed to the coarsening of the equilibrium phase and the widening of the precipitate-free zone. The high-angle annular dark field results provided the direct evidence of the induced-precipitation effect of Al3Zr particles during the quenching process.