Patent ID: 8118116
Filing Date: 2012-02-21
Classification: C21D,C22C,E21B

Abstract:
1. An elongated percussive rock drilling element comprising at least one thread portion and a flush channel, at least said thread portion being made of a corrosion resistant steel having a structure with a martensite content of greater than about 50 wt-% and less than about 100 wt-%, in which the steel comprises C+N greater than about 0.1 wt-% and less than or equal to about 0.8 wt-% and Cr greater than or equal to about 11 wt-% or Cr greater than or equal to about 5 wt-%, Mo less than or equal to about 5 wt-%, W less than or equal to about 5 wt-%, Cu less than or equal to about 2 wt-%, Mo+W+Cu>0.5 wt-% or Cr+3.3 (Mo+W)+16N greater than about 10 wt-%, wherein the surface of said at least one thread portion of said corrosion resistant steel is ball blasted.