Heat Treatment
Also known as: Stress Relief, Annealing, Solution Treatment, Ageing, Precipitation Hardening
Heat treatment encompasses a range of controlled thermal cycles applied to AM metal parts after printing: stress relief (reduces residual stress without phase change), annealing (recrystallisation, grain growth), solution treatment (dissolves precipitates), and ageing/precipitation hardening (forms strengthening precipitates). Each cycle targets a specific metallurgical outcome — from relieving the high residual stress inherent to LPBF rapid solidification to achieving peak hardness in age-hardenable alloys.
Why AM parts need this
AM metals are produced with residual tensile stresses from rapid thermal gradients during solidification. Without stress relief, distortion occurs on build-plate removal and fatigue life is significantly reduced. LPBF IN718 in the as-built condition has tensile strength but poor ductility; solution + double ageing (AMS 5663) is required to achieve the specified creep-resistant microstructure. For tool steels (MS1 maraging), direct ageing after LPBF achieves 50–54 HRC without quenching — a major advantage over conventional tool steel heat treatment.
Key parameters
Must remain below beta transus (995 °C) to preserve fine grain. Argon atmosphere or vacuum essential — Ti oxidises above 500 °C.
Removes residual stress without dissolving delta phase. Precedes solution treatment.
AMS 5663 double-ageing: maximises gamma-prime/double-prime strengthening.
LPBF MS1 can be aged directly (no solution treatment required). Achieves 50–54 HRC. EOS recommendation.
AMS 5622 H900 condition: 1310 MPa UTS typical for LPBF 17-4PH. Higher aging temperatures reduce strength, increase ductility.
Compatible materials
Limitations
- Atmosphere control is critical — vacuum or inert gas mandatory for titanium above 500 °C
- Distortion can occur during stress relief if part is not properly fixtured — consult supplier
- LPBF aluminium alloys (AlSi10Mg) are sensitive to over-ageing — temperature uniformity ±3 °C required
- Heat treatment cannot repair surface-connected porosity or dimensional out-of-spec features
Related tools
Providers
Bodycote
World's largest provider of HIP, heat treatment, and surface technology services for AM and conventionally manufactured components.
Macclesfield, GB
Solar Atmospheres
US vacuum heat treatment specialist operating NADCAP-accredited furnaces for stress relief, annealing, ageing, and brazing of AM titanium, nickel, and aluminium parts.
Souderton, PA, US
Wallwork Group
UK specialist in vacuum heat treatment, HIP, and PVD coating for aerospace and medical AM parts — NADCAP-accredited, Cambridge.
Cambridge, GB
Ipsen International
US/German vacuum furnace OEM — batch and continuous vacuum heat treatment systems for stress relief, solution annealing, and ageing of LPBF and EBM metal parts. Based in Rockford, IL.
Rockford, IL, US
ALD Vacuum Technologies
Hanau Germany vacuum metallurgy and heat treatment specialist — ALD furnaces for vacuum annealing, ageing, and HIP+heat-treat of LPBF titanium, nickel, and tool-steel AM components to aerospace specifications.
Hanau, DE
Seco/Warwick Group
Swiebodzin Poland — vacuum furnaces, fluidised bed furnaces, and VVPHT systems for AM post-processing heat treatment of aerospace titanium, nickel, and aluminium — serving EOS, SLM, and service bureau customers.
Swiebodzin, PL
Paulo Products
US Midwest thermal processing specialist — NADCAP-accredited heat treatment, atmosphere brazing, and salt bath nitrocarburising for AM steel and nickel components.
St Louis, MO, US
Relevant standards
Cycle parameters from AMS 2801D, AMS 5663N, EOS application notes (manufacturer tier). Ti stress-relief range from debroy-2018-review (peer-reviewed).
All post-processing