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Solution Annealing

Solution annealing is a treatment process that alters the metallurgical structure of a material, resulting in a change to its mechanical and electrical properties. In this process, we heat parts to the temperature at which secondary phases dissolve into a single phase and then cool the material to prevent secondary phases from precipitating and reversing the change.


Related Processes

Common Alloys that we treat with Solution Annealing

  • Precipitation Hardening Stainless Steels, e.g., 13-8, 15-5, 15-7, 17-4
  • Austenitic Stainless Steels, e.g., 304, 316
  • 2xx, 3xx, 7xx, 8xx, 2xxx, 6xxx, and 7xxx Aluminums, e.g., A356, 6061, 7075
  • Precipitation Hardening Copper Alloys, e.g., C17000, C17200, C954
  • Some Superalloys, e.g., Monel, Inconel 718

TMT’s Equipment and Variations of Solution Annealing

Parts can be solution annealed in air, vacuum, or endothermic furnaces. Depending on the temperature of the process some scaling or decarburization can occur if processed in air. 

The quench media is dependent on the grade of steel and size of part. Parts can be quenched in water, oil, gas, or air. Some precipitation hardened stainless steels will also include a cold stabilization [sub-zero] step between solution annealing and aging. 

Applications​ of Solution Annealing

  • Precipitation-hardened stainless steels are used extensively in corrosive environments where more strength is needed than 300 series stainless steels can provide. Depending on the material grade, they can be hardened up to the mid/low 40s HRC. Aging at higher temperatures will reduce the strength and hardness, but in general increase the corrosion and impact properties. One advantage of precipitation hardened stainless steels is the ability to machine parts in the solution annealed state and then subsequently age the parts to cut down on distortion.​These types of stainless steels have applications ranging from shafts and gears to medical equipment.  
  • Aluminums are aged to improve mechanical properties. Peak strength is obtained by aging to the T6 condition. Some alloys are over-aged to the T7 condition to reduce susceptibility to stress-corrosion cracking. Aged aluminums see frequent use in aerospace and other applications where high specific strength is needed.
  • Precipitation-hardened copper alloys are used in applications where higher strength is required than can be obtained with typical alloys. Alloying elements, such as Beryllium, are used to increase the hardness. Electrical conductivity will be decreased compared to ETP coppers, but components can have hardness up to 45 HRC. They are often used for bushings, bearings, small gearing among others.

Associated Specs/Standards

  • AMS QQ-A-367, 2759/3, 2770, 2772, 4020, 4021, 4022, 4023 4025, 4026, 4027, 4038, 4039, 4043, 4044, 4045, 4046, 4047, 4048, 4049, 4053, 4078, 4079, 4080, 4082, 4081, 4083, 4115, 4116, 4117, 4122, 4123, 4124, 4127, 4128, 4129, 4139, 4146, 4150, 4154, 4160, 4161, 4167, 4168, 4169, 4170, 4172, 4173, 4676, 5528, 5529, 5568, 5604, 5644, 5617, 5622, 5643, 5659, 5673, 5678, 5824, 5825, 6532, 6875, 7199
  • ASTM A313, A510, A564, A579, A693, A705, A995, B209, B210, B211, B221, B234, B241, B247, B308, B313, B316, B345, B404, B429, B444, B483, B457, B549, B632, B808
  • ASME SA564, SA693, SA705
  • MIL 1684
  • SAE J454, J467

What To Consider When Specifying

  • Material
  • Furnace Atmosphere
  • Hardness (if required)
  • Mechanical Testing (if required)
  • Specification (if required)

Still have questions?

For more information, or if you’re ready to get started, feel free to contact us today!