An orange peel surface can form during bending or working after annealing. This is a result of recrystallization and "over-annealing" the sample. When the grain size becomes too large, the grains cannot accommodate shape change during working or annealing.
To avoid this, we need to ensure the grain size remains small. You can either anneal the sample at a lower temperature (it still needs to be high enough for recrystallization to occur), or for a shorter period of time. This will reduce the grain size so the microstructure can better accommodate shape changes, resulting in smaller surface roughness.
Want to understand more? Read about recrystallization here.
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