Drill rod material: the drill rod links the drill bit and tail, transmitting impact energy, torque and flushing. Drill rod material must be high‑hardness steel with tuned C, Cr, Mo, Ni; Mn and Si control toughness and yield. Two connection types—tapered (shallow) and threaded (deep/extendable). Common specs B19/B22/B25, lengths 0.3–3m (some to 10m) and weights ~2.26–3.96 kg/m. Select drill rod material by rig type and hole depth.