CPC F02F 1/40 (2013.01) [C21D 1/09 (2013.01); C21D 5/00 (2013.01); C21D 9/0068 (2013.01); C21D 2221/01 (2013.01); F02F 2200/00 (2013.01)] | 6 Claims |
1. A cylinder head to be attached to a cylinder block with an opening formed on a first surface of the cylinder block, wherein
a second surface of the cylinder head on a side to be attached to the cylinder block includes a first portion overlapping the opening and a second portion overlapping the first surface except the opening; and
the second portion includes a first region and a second region having hardness higher than that of the first region.
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