Microstructures and hardness of stir zone for friction stir processed and post-processed heat treatment 7B04-O aluminium alloy

7th International Conference on Nanomaterials by Severe Plastic Deformation

Chen, Y.^1 ; Ding, H.^1 ; Li, J.Z.^2

School of Material Science and Engineering, Northeastern University, Shenyang

110819, China^1

AVIC, Beijing Aeronautical Manufacturing Technology Reaserch Institute, Beijing

100024, China^2

关键词: Base metals;    Dissolution rates;    Friction stir;    Friction stir processing;    Heat input;    Rotation speed;    Stir zones;    Thin sheet;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/194/1/012031/pdf
DOI  :  10.1088/1757-899X/194/1/012031

来源: IOP

【 摘 要 】

Friction stir processing (FSP) with different rotation speeds was conducted on 7B04-O aluminium alloy thin-sheet, then the post-processed heat treatment (PPHT) was carried out. The microstructures and hardness of the stir zone (SZ) under as-processed (AP) and PPHT states were investigated. The result showed that the hardness of the SZ was enhanced under the AP state, attributing to the grain refinement. The effect of PPHT on the hardness of the material was different, compared with the AP state, the hardness of the SZ with a low rotation speed under PPHT state was deteriorated while it was enhanced when high rotation speed was adopted. When FSP was conducted on the O-temper base metal (BM), the initial precipitates in the matrix were coarse and stable, reducing the dissolution rate of the precipitates. High heat input was required in order to induce sufficient dissolution of the precipitates, which was beneficial to elevating the impact of PPHT on hardness. The amount and morphology of the precipitates played important roles in the SZ of improvement in hardness.