| US 7,571,779 B2 | ||
| Drill rod and method of manufacture thereof | ||
| Ann-Cathrin Hedlund, Sandviken (Sweden); and Kenneth Larsson, Sandviken (Sweden) | ||
| Assigned to Sandvik Intellectual Property Aktiebolag, Sandviken (Sweden) | ||
| Filed on Mar. 24, 2005, as Appl. No. 11/87,799. | ||
| Application 11/087799 is a continuation of application No. PCT/SE03/01476, filed on Sep. 22, 2003. | ||
| Claims priority of application No. 0202814 (SE), filed on Sep. 24, 2002. | ||
| Prior Publication US 2005/0217901 A1, Oct. 06, 2005 | ||
| Int. Cl. E21B 17/04 (2006.01); B21K 5/02 (2006.01) | ||
| U.S. Cl. 175—320 [76/108.2] | 20 Claims |
| 1. A drill rod for percussive rock drilling comprising:
a first rod part comprising first and second ends, an inner duct, and an external thread disposed adjacent the first end,
wherein the external thread is at least partly hardened by heat treatment; and
a second rod part comprising first and second ends, an inner duct, and an internal thread disposed adjacent the first end
thereof, wherein the internal thread is at least partly hardened by heat treatment,
wherein the second end of the first rod part and the second end of the second rod part are welded together to define a weld
zone having a substantially martensitic structure, and
wherein the hardening of the external and internal threads is performed to achieve a hardness in the range of 440 to 750 HV1.
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