Heat Treatment of Metals

The final characteristics of a metal, particularly its mechanical properties (like strength and hardness), are strongly determined by its manufacturing history. Processes such as heat treatment (controlled heating and cooling), mechanical work (shaping), and strain hardening (cold working) all significantly alter the material’s condition, the results of which are summarized below.

Steel Heat Treatment

Steel Heat Treatment
Condition	Description
Annealed	Heat-treated to a soft state
Normalized	Heat-treated to a soft state to control grain structure (soft state here: softer than an un-treated or heavily worked state, harder than Annealed)
Hardened & tempered	Heat-treated, quenched and tempered to achieve higher hardness
Tempered at ___°C	Hardened and tempered. Temperature chosen to achieve specific hardness
Aged	Solution heat-treated and precipitation hardened
H900 / H1025 / H1150 etc.	Solution heat-treated and precipitation hardened (aged) at 900°F / 1025°F / 1150°F etc.
1/4 hard	Partially hardened through cold work
1/2 hard	Partially hardened through cold work
3/4 hard	Partially hardened through cold work
Full hard	Fully hardened through cold work

Aluminum Alloys Heat Treatment

Aluminum Alloys Heat Treatment
Condition	Description
F	As-fabricated
O	Annealed
W	Solution heat-treated only

T1	Cooled from an elevated temperature shaping process and naturally aged
T2	Cooled from an elevated temperature shaping process, cold worked, and naturally aged
T3	Solution heat-treated, cold worked, and naturally aged to a substantially stable condition
T4	Solution heat-treated and naturally aged to a substantially stable condition
T5	Cooled from an elevated temperature shaping process and artificially aged
T6	Solution heat-treated and artificially aged
T7	Solution heat-treated and overaged or stabilized
T8	Solution heat-treated, cold worked, and artificially aged

H1..	Strain-hardened only
H2..	Strain-hardened and partially annealed
H3..	Strain-hardened and stabilized
H4..	Strain-hardened and coated
	The second number refers to the degree of strain hardening: from 2 (1/4 hard) to 8 (fully hard) e.g. H32 = Strain-hardened (1/4 hard) and stabilized

Titanium Alloys Heat Treatment

Titanium Alloys Heat Treatment
Condition	Description
Annealed	Heat-treated to a soft state
Solution treated	Heat-treated typically 800–1000°C and water quenched (intermediate stage)
Solution treated and single aged	Solution heat-treated, water quenched and aged typically 400–600°C
Solution treated and duplex aged	Solution heat-treated, water quenched and aged typically 400–600°C
Solution treated and triplex aged	Solution heat-treated, water quenched and aged typically 400–600°C

Nickel Alloys Heat Treatment

Nickel Alloys Heat Treatment
Condition	Description
Annealed / Solution treated / Equalized	Heat-treated at high temperature to a soft state
Aged	Solution heat-treated and aged (precipitation hardened) to increase strength