FAQ - Secondary Treatments

Q: What is green machining?
A: Green machining is the machining of a part prior to the sintering process. In general, this is not done with conventionally processed P/M parts, since they do not have sufficient green strength. However, with the introduction of ANCORDENSE® and ANCORMIX™ technologies, green parts can be manufactured with green strengths in the range of 3500 psi to 6000 psi. These green strengths are sufficient to facilitate the thrusting and clamping forces realized in machining process.
Q: Can P/M parts be heat treated?
A: Yes, heat treatment generally involves heating into the austenitic phase region followed by controlled cooling to achieve a desired microstructure. There are different types of heat treatment operations:
  • Normalizing and annealing utilizes slow cooling rates to develop a ferrite/ pearlite microstructure well suited for machining, welding, and cold working
  • Neutral hardening and case hardening utilize a rapid cooling or quench in oil to develop a martensitic microstructure; the process results in maximum strength and apparent hardness
  • The use of salt baths is avoided because of entrapment of the compounds in the pores of the parts
Q: Can P/M parts be welded or brazed?
A: Yes, ferrous P/M parts can be welded or brazed successfully. Most conventional welding methods are applicable:
  • Resistance Projection Welding
  • Gas Tungsten Arc (GTA or TIG)
  • Gas Metal Arc (GMA or MIG)
  • Electron Beam Welding
  • Laser Beam Welding
  • Friction Welding
  • CD Welding

P/M parts can be brazed with a special filler material Ancorbraze 72. Multiple P/M parts may be joined using diffusion or sinter-bonding.