Vacuum Age Hardening (Precipitation Hardening)
Enhance the strength of metals and alloys
Vacuum Age Hardening (Precipitation Hardening)
Age Hardening (Precipitation Hardening): Overview and Process
Age hardening, also known as precipitation hardening, is a heat treatment process used to enhance the strength of metals and alloys. This process strengthens the metal by forming solid precipitates within the metal’s structure, thus the name “precipitation hardening.” The treatment involves “aging” the metal by either heating it or storing it at lower temperatures, encouraging the formation of these precipitates.
Malleable metals and alloys, such as those of nickel, magnesium, and titanium, are well-suited for age hardening. Through this process, tensile and yield strength are significantly increased. The precipitates act as obstacles to dislocation movements or defects within the metal’s crystal lattice, leading to a stronger, more durable structure. To achieve this precipitation, metals and alloys need to be maintained at high temperatures for extended periods, hence the term “age hardening.”
In the case of PH (precipitation-hardened) stainless steels, heating between 900°F and 1200°F causes secondary phase particles to precipitate from the solid solution, creating a robust strengthening effect.
Advantages of Age Hardening
Age hardening offers several benefits, including:
- Increased tensile and yield strength
- Enhanced wear resistance
- Improved machinability due to structural uniformity
- Greater dimensional stability, reducing deformation over time
Industrial Applications of Age Hardening
Age hardening is essential in numerous industries for reinforcing metals and alloys. Common applications include:
- Strengthening alloys of aluminum, nickel, iron, and titanium
- Hardening critical components, such as gate valves, engine parts, shafts, gears, and plungers
- Reinforcing balls, bushings, turbine blades, fasteners, molding dies, and nuclear waste containers
- Treating aircraft components, processing equipment, and valve stems
Additionally, precipitation hardening can be combined with other processes, such as nitriding, to further reduce costs and enhance the resulting material properties, making it a versatile and cost-effective solution in material engineering.
Unique Capabilities
- Large furnace capacity (up to 48 feet)
- Vacuum levels to 1×10-6 torr
- Hardness testing
- On-site metallurgical test lab
- Conformance to AMS and MIL specifications
- Production or one-off jobs
- Cryogenic stabilization processing
Materials Processed
- 17-4PH/15-5PH Stainless Steel
- 17-7/15-7 PH Stainless Steel
- 13-8MO, A-286
- AM350/355
- Custom 450/455/465
- Maraging Alloys
- Inconel Alloy 718
- Inconel Alloy X-750
- And many others!
Ask the Expert:
FAQs
Precipitation age hardening, also known as age hardening, is a heat treating process used to increase the strength, hardness, and wear resistance of precipitation-hardenable (PH) alloys. The process begins by solution treating the material, followed by rapid cooling to create a supersaturated structure. The alloy is then reheated to a relatively low temperature—typically between 900°F and 1,150°F—to allow fine precipitates to form throughout the metal. These microscopic precipitates strengthen the alloy without significantly affecting its dimensional stability.
Proper time and temperature control are critical during precipitation hardening. Excessive aging temperature or prolonged hold times can result in overaging, where the strengthening precipitates become too large and the material begins to lose hardness and strength. Carefully controlled thermal processing ensures the alloy achieves its specified mechanical properties.
The most commonly processed precipitation-hardening alloys include:
- 15-5 PH stainless steel
- 17-4 PH stainless steel
- 13-8 Mo stainless steel
- 17-7 PH stainless steel
- 15-7 Mo stainless steel
- A-286
- Custom 4XX series alloys
- Other nickel- and cobalt-based age-hardenable alloys
These materials are widely used in industries requiring high strength, corrosion resistance, and excellent dimensional stability.
Precipitation-hardening alloys offer several important manufacturing advantages:
- High strength and hardness after heat treatment
- Excellent corrosion resistance
- Outstanding dimensional stability
- Good toughness and fatigue resistance
- Components can be machined or formed in a softer condition before final hardening
- Low-temperature aging minimizes distortion compared to many conventional hardening processes
These characteristics make PH alloys ideal for precision components with tight dimensional tolerances.
Yes. Some precipitation-hardening stainless steels, particularly copper-bearing grades such as 17-4 PH and 15-5 PH, require specialized vacuum furnace procedures. Proper furnace practices are necessary to prevent copper contamination within the vacuum system while maintaining the bright, clean surface finish and repeatable results expected from vacuum processing.
An experienced commercial heat treater understands these requirements and employs dedicated procedures to ensure consistent quality.
PH alloys are used in many critical industries, including:
Aerospace & Defense
- Landing gear components
- Engine and turbine hardware
- Structural components
- High-strength fasteners
Medical
- Surgical instruments
- Orthopedic devices
- Medical tooling
Oil & Gas
- Valves
- Valve stems
- Pumps
- Springs
- Wear components
Industrial Manufacturing
- Shafts
- Gears
- Precision machined components
- Tooling
PH alloys provide an excellent combination of high strength, corrosion resistance, fatigue performance, and dimensional stability. Because aging occurs at relatively low temperatures, precision-machined aerospace components can achieve their required mechanical properties with minimal distortion, reducing finishing operations and improving dimensional accuracy.
51ÁÔÆæ combines more than 40 years of metallurgical expertise with advanced vacuum furnace technology and rigorous quality systems to deliver consistent, repeatable results. Our tightly controlled heat treating processes, calibrated instrumentation, and experienced metallurgical staff ensure PH alloys meet demanding customer and industry specifications.
51ÁÔÆæ is a trusted partner for precision precipitation hardening, offering:
- Over 40 years of heat treating experience
- Advanced vacuum and atmosphere furnaces
- Furnace capacities ranging from laboratory-sized systems to 48-foot-long vacuum furnaces
- Nadcap-accredited quality systems
- Comprehensive process documentation and traceability
- On-site mechanical testing capabilities at select facilities, helping reduce turnaround time for certification and final delivery