A link (30,130) for a track chain (24,124) in a ground-engaging track system for a machine comprising: an elongate link body including an inboard side and an outboard side, and defining a first track pin bore formed in a first link body end and a second track pin bore formed in a second link body end, each of the first and second bores (36,38) communicating between the inboard and outboard sides (32,34) and being configured to receive a track pin therein for coupling the elongate link body with another elongate link body in the track chain (24,124); the elongate link body further including a flat lower surface configured to contact a track shoe bolted to the elongate link body, and an upper rail surface (42,142) configured to contact a rotatable track-engaging element (16,20,23) in the track system; the elongate link body further defining a first and a second window (48,50) each communicating between the inboard and outboard sides (32,34), and a first and a second bolting bore (52,53) each extending inwardly from the lower surface and intersecting the first and second windows (48,50), respectively; characterized in that the upper rail surface (42,142) is formed of a sacrificial wear material and has a convex longitudinal profile configured to delay scallop formation in the upper rail surface (42,142) resulting from the contact with the rotatable track engaging element (16,20,23); the upper rail surface (42,142) further includes a first end section, a second end section, and a center section forming the convex longitudinal profile and extending between the first and second end sections (54,56); and wherein the first and second end sections (54,56) are flat, positioned in a common plane, and parallel to the lower surface; wherein the link body has a body length, and the center section defines a uniform radius of curvature greater than the body length; and wherein the uniform radius of curvature is from about 500mm to about 1000mm. an elongate link body including an inboard side and an outboard side, and defining a first track pin bore formed in a first link body end and a second track pin bore formed in a second link body end, each of the first and second bores (36,38) communicating between the inboard and outboard sides (32,34) and being configured to receive a track pin therein for coupling the elongate link body with another elongate link body in the track chain (24,124); the elongate link body further including a flat lower surface configured to contact a track shoe bolted to the elongate link body, and an upper rail surface (42,142) configured to contact a rotatable track-engaging element (16,20,23) in the track system; the elongate link body further defining a first and a second window (48,50) each communicating between the inboard and outboard sides (32,34), and a first and a second bolting bore (52,53) each extending inwardly from the lower surface and intersecting the first and second windows (48,50), respectively; characterized in that the upper rail surface (42,142) is formed of a sacrificial wear material and has a convex longitudinal profile configured to delay scallop formation in the upper rail surface (42,142) resulting from the contact with the rotatable track engaging element (16,20,23); the upper rail surface (42,142) further includes a first end section, a second end section, and a center section forming the convex longitudinal profile and extending between the first and second end sections (54,56); and wherein the first and second end sections (54,56) are flat, positioned in a common plane, and parallel to the lower surface; wherein the link body has a body length, and the center section defines a uniform radius of curvature greater than the body length; and wherein the uniform radius of curvature is from about 500mm to about 1000mm.