HEAT TREATMENT OF STEEL PARTS, PARTICULARLY FRICTION-WELDED STEEL PARTS
A heat treatment process for a non-quench hardened steel article or friction-welded steel article including normalizing and annealing steps whereby uniformity of microstructure and hardness are significantly improved.
1 . A method of heat treating a non-quench hardened steel article, said method comprising:
heating said article to a first hold temperature in the range of about 1650° F. to about 1750° F.;
cooling said article to room temperature in a first cooling step;
heating said article to a second hold temperature in the range of about 1200° F. to about 1250° F.;
cooling said article to room temperature in a second cooling step.
2 . The method of claim 1 wherein said article is held at said first hold temperature for a period of at least six hours.
3 . The method of claim 1 wherein said first cooling step takes place in air.
4 . The method of claim 1 wherein said first cooling step takes place in slightly agitated air.
5 . The method of claim 1 wherein said article is held at said second hold temperature for a period of at least four hours.
6 . The method of claim 1 wherein said second cooling step comprises furnace cooling to about 600° F. followed by cooling in air to room temperature.
7 . The method of claim 1 wherein said second cooling step comprises cooling in air to room temperature.
8 . The method of claim 1 wherein said steel article comprises AISI 9310 steel.
9 . The method of claim 1 wherein said steel article comprises AISI 3310 steel.
10 . The method of claim 1 wherein said steel article comprises a gear.
11 . The method of claim 10 wherein said gear further includes a hub friction welded thereto.
12 . The method of claim 1 wherein said steel article comprises a friction-welded steel article.