7050 aluminum alloy forgings high-speed rail

With the rapid development of China's industrialization process, high-speed rail has become the main mode of transportation. Lightweight is the most important factor for high-speed rail to speed up

Important means, and "replacing steel with aluminum" is one of the key technologies to realize the lightweight of high-speed railway. High strength aluminum alloy forgings can be used for bogie, door seat, cylinder head and other parts on the high-speed railway body to realize the lightweight of high-speed railway. 7050 aluminum alloy has high specific strength, excellent strength and toughness, good processability and better corrosion resistance. It is one of the key materials for the lightweight of high-speed railway body. 7050 aluminum alloy is a heat treatable strengthening alloy. Through reasonable heat treatment process, it can not only eliminate the residual stress caused by plastic processing, but also make the alloy have better comprehensive properties. The results show that the two-stage solid solution can improve the overall mechanical properties and stress corrosion resistance of 7050 aluminum alloy thick plate. Multistage enhanced solid solution is conducive to the recovery in the process of solid solution, so that 7050 aluminum alloy has higher strength and fracture toughness. The effect of single-stage and double-stage aging process on the microstructure of 7050 aluminum alloy. It is found that the rapid cooling before secondary aging is conducive to the improvement of alloy strength.

7050 aluminum alloy forging high speed rail, cut the sample from it and pass through the system， through systematic heat treatment process test, combined with microstructure analysis, find a better heat treatment process scheme to make the alloy achieve a good match of strength, plasticity and conductivity, so as to meet the requirements for use on high-speed railway.

1) When 7050 aluminum alloy forging high speed rail is heat treated with different solid solution systems, the two-stage solid solution can significantly improve the tensile strength, yield strength and conductivity of the alloy, but reduce the elongation. The tensile strength, yield strength and conductivity of the alloy under the step-by-step solid solution system are the best of the three solid solution systems, but there is little difference with the two-step solid solution, and the elongation is higher than that of the single-step solid solution.

2) When 7050 aluminum alloy is aged by different aging systems, the alloy with single-stage aging has higher yield strength, tensile strength and elongation, but its conductivity is the lowest compared with other aging systems; The yield strength, tensile strength and elongation of the alloy are lower than those of single-stage aging, but the conductivity is higher than that of other aging systems; When the aging system is 120 ℃ for 6 H + 190 ℃ for 0.5 h + 120 ℃ for 24 h, the tensile strength of the alloy is 589.18 n / mm2, the yield strength is 574.62 n / mm2, the elongation is 9.17% and the conductivity is 35.75% IACS.

3) Compared with the TEM microstructure of the alloy under different aging systems, the precipitates in the crystal are fine and dispersed, the precipitates at the grain boundary are continuously distributed, and the PFZ is not obvious; During double aging, the precipitates at the grain boundary are discontinuous, the number of precipitates in the crystal is less, the size increases, and there is obvious PFZ; In the process of regression re aging, the precipitates at the crystal boundary are coarsened and discontinuous, the precipitates in the crystal are fine and dispersed, and the PFZ is slightly narrower than that in the two-stage aging state.