Thread extension steel bars for rock drilling include extension rod, MF rod, light extension drill rod, drifter rod, shank adapter drill rod etc. We can also call such thread extension drill rod as threaded drill rod or threaded pipe, they own one end thread or both ends thread, with hollow round body or hollow hexagonal body. It is the main part of the threaded connection drilling tools or drilling equipments. Threaded drill rod is connected with top hammer rock drill rigs via shank adaptors & couplings, another end, they are connected with drill bits via thread also. Threaded rod could be connected with other drill rods to constitute a complete set of threaded connection whole drilling tools for drilling. Threaded drill rods could be connected with one piece of shank adapters and drill bits, or connected with lots of adaptors and bits. And ther can also be used in shallow holes and small diameter rock hole drilling, the applicable scope is wide, drilling speed, impact energy transmission loss is small, high drilling efficiency, easily to realize the drilling mechanization and improve the superiority of drilling conditions. Therefore, thread extension drill rods share a very very big proportion in the whole drilling fields. Thread extension steel bars for rock drilling must own high fatigue strength, elasticity, rigidity and toughness, but strength and toughness is contradictory. The thread at both ends of the thread rods is a whole set of drilling tools, it's the key part of rod. It is well known that the performance of the material could be played well only after going through heat treatment to release its maximum potential, therefore, the choice of material and heat treatment process are important on an equal basis. R32, R38, T38, T45, T51, T60 Thread Extension Rod: (1) Threaded Connection: R22, R25, R32, R38, T38, T45, T51, and so on. (2) Diameter: OD32, OD38, HEX32, HEX35, And so on. (3) Length: 600-6400mm. (4) Package: Wooden cases or wrapped with plastic knitting and then packed into bundles or as per your requests.