Contacting and breaking rock during operation, drill bits are subjected to huge impact loads and abrasive wear. As application conditions are extremely severe, the requirements for body steels are also relatively special.
The basic requirements include
1. the steels have high plasticity, toughness and hardness after heat treatment;
2. the steels must have high fatigue strength and wear resistance;
3. the steels must have high air-cooling harden ability;
4. the heat treatment process is simple, and the cost is low.
If the hot inserting process is used, body steels must have the following points
a) the hardness must reach the requirement of 40~50HRC after heat treatment,;
b) the steels have high-strength physical properties to ensure high fixing strength;
c) the steels have certain high temperature strength and thermal stability to ensure the fixing strength during operation;
d) the steels have high fatigue resistance and wear resistance;
e) the steels have high linear expansion coefficient and tempering stability;
f) the steels are easy to be softened and annealed, and have good dimensional stability and machinability which includes cutting performance, reaming performance, smoothness, etc.