The Brinell hardness values of 7075 rheo squeeze casting samples after solution treatment at different time were counted in the table. As shown in the figure corresponding to the data in table 5.5, the hardness curves of 7075 rheo squeeze casting parts under different solution time are drawn.
It can be seen from the figure that at the same solution temperature (475 ℃), with the increase of solution treatment holding time, the hardness first increases and then decreases, and reaches the maximum when holding time is 2H.
Based on the above analysis of the hardness and microstructure of the sample under different solution time, the suitable solution treatment process is 475 ℃× 2H.