Steps

Coarse grain specimen

Ultrafine grain specimen

1

Solid solution traetment (850˚C/1h)

Solid solution traetment (850˚C/1h)

2

Water quenching

Water quenching

3

Pre-straining (4%, 6%, and 8%)

Producing UFG microstructure by CGP

4

Baking (250˚C and 250˚C for 20 min)

Pre-straining (4%, 6%, and 8%)

5

Tensile testing at room temperature

Baking (250˚C and 250˚C for 20 min)

6

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Tensile testing at room temperature