What is heat treatment of nonferrous metals?

Heat treatment of nonferrous metals

Heat treatment, combining heating and cooling, of nonferrous metals is a process to alter the metal properties, such as hardness, softness and ductility, without changing their shapes.
Examples of heat treatment of nonferrous metals are as follows:

Examples of heat treatment of nonferrous metals

Metal:
Copper alloys, aluminum alloys, magnesium, titanium alloys, gold, silver, etc.
Heat treatment:
Solution heat treatment, annealing, age hardening, etc.
Products:
Contacting materials, such as connector parts, automobile wheels, eyeglass frames, fashion accessories, automobile parts, aircraft parts and other parts

Heat treatment for each type of metal

Copper alloys and gold

These metals have high ductility and repeating heat treatment processes extends them to form thin sheets. Heat treatment is performed in a nitrogen atmosphere to restrict oxidation. When quick cooling is required, a nitrogen and hydrogen atmosphere is used for cooling.

Titanium alloys

An argon gas atmosphere is generally used because the nitrogen atmosphere causes nitriding and the hydrogen atmosphere causes embrittlement.

Aluminum alloys

Since the surface is covered with a tough oxide film, aluminum alloys are generally heat treated in an air atmosphere.

Thermal products in this category

Reference: Heat treatment of nonferrous metals

Copper alloy wrought materials

JIS Type Annealing Stress removal Aging
C1100 Tough pitch copper 260 to 650℃ 190℃ -
C2100 Red brass (95/5) 425 to 790℃ 205℃ -
C2300 Red brass (85/15) 425 to 730℃ 233 to 245℃ -
C2600 Brass (70/30) 425 to 700℃ 260℃ -
C2801 Brass (60/40) 425 to 600℃ 205℃ -
C3500 Free-cutting brass 425 to 650℃ 245℃ -
C4250 Phosphor bronze 480 to 680℃ 190℃ -
C7060 Nickel silver 590 to 815℃ 245℃ -
C1720 Beryllium copper 770 to 1,040℃ - 315℃
Notes 1)
Annealing softens the metal through recrystallization and crystal grain growth by heating metal hardened by cold working to temperatures higher than the recrystallization temperature.
Notes 2)
Stress removal is performed to prevent cracking due to aging, which is stress corrosion cracking, by removing residual stresses through heat treatment at temperatures below the recrystallization temperature. This process is applied to materials such as brass plates. Stress removal at low temperatures after cold working adds toughness, which improves spring properties. This technique is used for materials such as phosphor bronze plates.
Notes 3)
Aging treatment hardens the work by solutionizing the metal at high temperatures and then precipitating solute atoms at low temperatures. This process is applied to materials such as beryllium copper plates.

Aluminum alloy wrought materials

JIS Properties category Annealing Solutionizing Quenching Age hardening
1080
1100
1200
0 340 to 410℃
Air or furnace cooling
- - -
2014,
2014 Combined version
0 340 to 410℃
Air or furnace cooling
- - -
T4, T42, T3 - 495 to 505℃ Water cooling 96 hours or more at room temperature
T6, T62 - 495 to 505℃ Water cooling 170 to 180℃, 10 hours
2017 0 340 to 410℃
Air or furnace cooling
- - -
T4, T42, T3 - 495 to 510℃ Water cooling 96 hours or more at room temperature
2024,
2024 Combined version
0 Approx. 410℃
Air or furnace cooling
- - -
T4, T42, T3, T361 - 490 to 500℃ Water cooling 96 hours or more at room temperature
T62 - 490 to 500℃ Water cooling 185 to 195℃, approx. 9 hours
T861 - 490 to 500℃ Water cooling 185 to 195℃, 8 hours
3003
3203
0 340 to 410℃
Air or furnace cooling
- - -
3004
3005
0 340 to 410℃
Air or furnace cooling
- - -
5005
5254
5086
0 340 to 410℃
Air or furnace cooling
- - -
6061 0 340 to 410℃
Air or furnace cooling
- - -
T4, T42 - 515 to 550℃ Water cooling 96 hours or more at room temperature
T6, T62 - 515 to 550℃ Water cooling 155 to 165℃, 18 hours
7N01 0 Approx. 410℃ Furnace cooling - - -
T4 - Approx. 450℃, air or water cooling 1 month or more at room temperature
T6 - Approx. 450℃, air or water cooling Approx. 120℃, approx. 24 hours or more
7075,
7075 Combined version
0 340 to 410℃
Air or furnace cooling
- - -
T6, T62 - 460 to 510℃ Water cooling 115 to 125℃, 24 hours or more
Notes 1)
JIS symbols for properties categories
  • F: As manufactured
  • O: Annealing
  • H: Hardened
  • T4: Natural aging after solutionizing
  • T3: Cold working after solutionizing, then natural aging
  • T5: Cooling after high temperature treatment, then artificial aging
  • T6: Artificial aging after solutionizing
  • T8: Cold working after solutionizing, then artificial aging
  • T42: Treatment T4 performed by user
  • T62: Treatment T6 performed by user
  • T361: Cold working to 6% reduction in area after solutionizing
  • T861: Hardening by artificial aging on T36
Notes 2)
Age hardening time applies to metal thickness of 12 mm or less, and 30 minutes should be added for each increment of 12 mm.
Notes 3)
Annealing of heat treated work is performed by heating the work to about 410℃, and then maintaining that temperature for at least one hour. Cooling to 260℃ at a rate lower than 28℃ per hour is advisable.

Magnesium alloy castings

JIS Chemical composition(%) Solutionizing Artificial aging Tensile strength (kg/mm) Yield strength (kg/mm) Elongation (%)
Al Zn Mn RE Zr Si Cu Ni Mg (℃) (h) (℃) (h)
MC1 - F 5.3 to 6.1 2.5 to 3.5 0.15 to 0.6 - - 0.30 or less 0.10 or less 0.01 or less Remainder - - - - > 18 > 7 > 4
T4 380 to 390 10 to 4 - - > 24 > 7 > 7
T5 - - 260 4 > 18 > 8 > 2
T6 380 to 390 10 to 4 220 to 230 5 > 24 > 11 > 3
MC2 - F 8.1 to 9.3 0.4 to 1.0 0.13 to 0.5 - - 0.30 or less 0.10 or less 0.01 or less Remainder - - - - > 16 > 7 -
T4 410 to 420 16 to 24 - - > 24 > 7 > 7
T5 - - 170 to 215 16 to 4 > 16 > 8 > 2
T6 410 to 420 16 to 24 170 to 215 16 to 4 > 24 > 11 > 3
MC3 - F 8.3 to 9.7 1.6 to 2.4 0.10 to 0.5 - - 0.30 or less 0.10 or less 0.01 or less Remainder - - - - > 16 > 7 -
T4 405 to 410 16 to 24 - - > 24 > 7 > 6
T5 - - 230 5 > 16 > 8 -
T6 405 to 410 16 to 24 260 to 220 4 to 5 > 24 > 13 -
MC5 - F 9.3 to 10.7 0.3 or less 0.10 to 0.5 - - 0.30 or less 0.10 or less 0.01 or less Remainder - - - - > 14 > 7 -
T4 420 to 425 16 to 24 - - > 24 > 7 > 6
T6 420 to 425 16 to 24 230 to 205 5 to 24 > 24 > 11 > 2
MC6-T5 - 3.6 to 5.5 - - 0.50 to 1.0 - 0.10 or less 0.01 or less Remainder - - 220 to 175 8 to 12 > 24 > 14 > 5
MC7-T5 - 5.6 to 6.5 - - 0.60 to 1.0 - 0.10 or less 0.01 or less Remainder - - 150 48 > 27 > 18 > 5
T6 495 to 500 2 130 48 > 27 > 18 > 5
MC8-T5 - 2.0 to 3.1 2.5 to 4.0 - 0.50 to 1.0 - 0.10 or less 0.01 or less Remainder - - 215 5 > 14 > 10 > 2
Notes 1)
T4, T5 and T6 are used for magnesium castings, but T2 (cold working after high-temperature treatment, then natural aging) and F are also used.
Notes 2)
Thoroughly wash the work before heat treatment. Aluminum powder must be washed away so no powder remains.
Notes 3)
To prevent voids in Mg-Al-Zn-based alloys, gradually heat the work to the solutionizing temperature after putting it in the furnace at 260℃.
Notes 4)
Since magnesium alloys have lower sensitivity to quenching compared with aluminum alloys, air or hot water cooling is sufficient after solutionizing. However, forgings should be water cooled.
Notes 5)
Since magnesium alloys will ignite and burn at 430℃, use an atmosphere that prevents ignition in the furnace when solutionizing.

Titanium alloy wrought materials

Base MIL Distortion removal annealing
(℃×h)
Annealing
(℃×h)
Solutionizing(℃×h) Aging(℃×h)
α alloys Commercially Pure Titanium 538 to 593 × 1/3 to 2/3
524 to 538 × 1/2 to 1
471 to 495 × 2 to 4
416 to 440 × 7 to 8
538 to 816 ×0.03 to 2AC or slow cooling - -
α+β alloys Ti-3Al-2.5V 371 to 649 × 1/4 to 6 704 to 760 × 1 to 3AC - -
Ti-8Al-1Mo-1V 580 to 788 × 1/6 to 1.25 704 to 927 × 0.03 to 8AC 899 to 1,025 × 0.16 to 1.5WQ 538 to 621 × 824AC
Ti-6Al-6V-2Sn 538 to 593 × 1/2 to 3 704 to 816 × 1 to 3AC 843 to 899× 0.16 to 1WQ 469 to 606 × 2 to 8AC
Ti-6Al-2Sn-4Zr-6Mo - - 815 to 913 ×≧ 1AC or quicker 593 × 4 to 8AC
β alloys Ti-13V-11Cr-3Al 482 to 538 × 1/2 to 3 760 to 816 × 0.03 to 1 760 to 816× 0.16 to 1 440 to 525 × 2 to 60
Notes 1)
Use annealing for α alloys since solutionizing and aging have little effect.
Notes 2)
α+β alloys have high strength, but they do not allow cold working.
Notes 3)
Solutionizing β alloys improves cold workability, and aging them greatly increases their strength.
Notes 4)
Vacuum purge and an argon atmosphere are combined in the furnace to prevent oxidation.
Notes 5)
AC stands for air cooling and WQ stands for water quenching.

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