Track link for a track joint assembly having wear band with lengthwise-varied hardness

A track joint assembly for a ground-engaging track system in a machine comprising:

• a first track link;
• a second track link;
• a track pin coupling the first track link to the second track link;
• each of the first track link and the second track link including a first link strap having a track pin bore formed therein, a second link strap having a bushing bore formed therein, and a middle section connecting between the first link strap and the second link strap;
• each of the first and the second track links further including a lower shoe-mounting surface, and an upper rail surface, the upper rail surface being located in part upon each of the corresponding first link strap, second link strap, and middle section, and formed by a wear band of sacrificial wear material;
• the sacrificial wear material having a hardness that is varied lengthwise along the upper rail surface of the corresponding first or second track link to form a first relatively softer zone of a softer material located in the first link strap, a second relatively softer zone of the softer material located in the second link strap, and a relatively harder zone of harder material located at least in part within the middle section;
• and
• the sacrificial wear material having a hardness that is varied depthwise from the upper rail surface in the corresponding first or second track link, such that the softer material has a greatest depth from the upper rail surface at a location longitudinally between the middle section and an outer end of the respective first link strap or second link strap, and is progressively reduced in depth, from the location of greatest depth, in longitudinal directions toward each of the middle section and the outer end of the respective first link strap or second link strap.

A track link for a ground-engaging track system in a machine made according to a method comprising:

• heat treating an elongate link body having a first link strap, a second link strap, a middle section, and an upper rail surface, such that a material extending throughout the elongate link body is hardened to form a harder material;
• tempering the elongate link body such that a portion of the material that forms the upper rail surface is softened to form a softer material;
• forming, by way of the heat treating and the tempering of the elongate link body, a scallop-retarding pattern of material hardness that is varied lengthwise along the upper rail surface;
• and
• the scallop-retarding pattern of material hardness forming relatively softer zones of the softer material in each of the first and the second link straps, a relatively harder zone in the middle section of the harder material, and a wear band of the harder material extending lengthwise between an outer end of the first link strap and an outer end of the second link strap and depthwise between the relatively softer zones and a first bore in the first link strap and a second bore in the second link strap, respectively.