Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:
Before the present invention is described in greater detail, it should be noted that like elements are denoted by the same reference numerals throughout the disclosure.
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To provide different crystallographic orientations, the first and second metal pieces can be made of different metals. In an example, the first metal piece is made of a metal, such as stainless steel or alloy steel, having a mechanical strength higher than that of a metal, such as titanium, for the second metal piece. Examples of the metal suitable for each of the first and second metal pieces include stainless steel, alloy steel, molybdenum, vanadium, zirconium, titanium, aluminum, magnesium, and the like. The first metal piece is glued to the second metal piece. Alternatively, the first and second metal pieces can be bonded together by other suitable methods, such as welding, press fitting, interlocking, etc.
Different crystallographic orientations may also be provided by forming the first and second metal pieces at different forming conditions and by heat treating the first and second metal pieces at different heat treatment conditions. In addition, the first and second metal pieces may also be provided from the same metal plate by shearing the metal plate using a punch so that the metal plate is divided into a surrounding part having a hole and a middle part within the hole. When the middle part is rotated relative to the surrounding part, the crystallographic orientation of the middle part is different from that of the surrounding part.
Since the first and second metal pieces have crystalline phases with different crystallographic orientations, the striking stress imparted on the sweet spot region 311 of the striking plate 31 by a golf ball can reside on the sweet spot region 311 for a relatively long period by reducing the transmission rate of the striking stress from the sweet spot region 311 toward the non-sweet spot region 312. Therefore, a relatively large reactive force is imposed onto the stricken golf ball so that the stricken golf ball can travel a relatively far distance. Furthermore, the striking stability and the direction controllability of a golf club head can also be improved thereby.
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While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.