Trademark

Chemical composition

C

Si

Mn

P

S

Ni

Cr

Cu

≤

50

0.47~0.55

0.17~0.37

0.50~0.80

0.035

0.035

0.30

0.25

0.25

55

0.52~0.60

0.17~0.37

0.50~0.80

0.035

0.035

0.30

0.25

0.25

Trademark

Blank sample
Size/mm

Heat Treatment

Mechanical Properties

Hardness of steel delivery status/HBS

Normalizing

Quench

Tempering

σb/MPa

σs/MPa

δ5(%)

ψ(%)

Ak/J

≤

≥

No heat

Annealed steel

50

25

830

830

600

630

375

14

40

31

241

207

55

25

820

820

600

645

380

13

35

255

217