Golf club head

1. A hollow golf club head comprising

a face portion whose front face defines a club face for striking a golf ball,

a crown portion intersecting the club face at the upper edge thereof, and

a sole portion intersecting the club face at the lower edge thereof, wherein

at least a part of the crown portion or at least a part of the sole portion is made of a rolled steel, and

a rolling direction of the rolled steel is in the range of from 0 to 20 degrees with respect to a front-back direction of the head.

2. The golf club head according to claim 1 , wherein

the club head comprises a head main body formed by casting a metallic material and being provided with an opening on the crown portion, and

a crown plate made of the rolled steel and being attached to the head main body so as to close the opening of the crown portion.

3. The golf club head according to claim 2 , wherein

the rolled steel has a thickness in the range of from 0.3 to 0.9 mm.

4. The golf club head according to claim 2 , wherein

the crown plate comprises a center portion and a peripheral portion surrounding the center portion, and

the center portion has a thickness smaller than the peripheral portion.

5. The golf club head according to claim 4 , wherein

a thickness of the peripheral portion is in the range of from 0.4 mm to 0.9 mm, and

a thickness of the center portion is in the range of from 0.3 mm to 0.6 mm.

6. The golf club head according to claim 2 , wherein

the head main body has a crown edge portion surrounding the opening in the crown portion, and

the crown edge portion has the same thickness with the peripheral portion of the crown plate.