... treatment production line and forging equipment and friction welding machine drill collars, the most complete processing equipment ... Liande can provide sucker rods including grade C, K, D, KD, HL, HY and KH. Among them, ... is not susceptible to sulphuric stress cracking. Grade D sucker rod is made from fine alloy steel ... the same size and main parameter as grade D sucker rod, but their strength is capable ...