We can manufacture square drill kellys and hexagonal drill kellys as per requirements of customers. They are made of aisi 4145h forged or rolled alloy structural steel. Quenching plus tempering thermal treatment will be conducted over the whole length. Its brinell hardness can reach 285-341 on the basis of such thermal treatment. Charpy impact energy: >or =54j. The formulated process can ensure that the misalignment of the hole reaches the standard wall thickness. Kelly bars are manufactured according to api-7-1 spec. Bound with steel band
