Stress-relief annealing
Ensure dimensional accuracy and dimensional stability
Stress-relief annealing is a heat treatment process used to specifically reduce internal residual stresses in steel components. These stresses are often caused by uneven cooling after casting, welding, or forging, but can also result from intensive mechanical machining.
Machining processes such as milling, turning, drilling, or deep drawing cause localized plastic deformation in the material structure, resulting in residual stresses. If these stresses are not specifically reduced, they can be released during subsequent manufacturing or heat treatment steps, causing dimensional and shape deviations (warping).
In particular, parts with tight dimensional tolerances or components that undergo further processing—such as nitrocarburizing or other thermochemical processes —must be in a low-stress state to ensure reproducible results.
Stress-relief annealing is typically performed at temperatures between 550 and650°C. Once the target temperature is reached, the workpieces are held at that temperature for about two hours to allow internal stresses to dissipate evenly. The workpieces are then slowly cooled in the furnace to prevent new stresses from forming due to temperature differences.
Controlled, slow cooling is particularly crucial for large or solid components, as cooling too quickly can cause stress to build up in the material again.
Stress-relief annealing does not affect the material’s microstructure and has only a minimal effect on hardness. The goal is not to alter mechanical properties, but to ensure dimensional, geometric, and process stability in subsequent manufacturing steps.
KEY FIGURES FOR SOFT ANNEALING
Temperature:
up to 650°C
System size:
900 x 2000 mm
Processing time:
48 hours or more
Max. load capacity*:
2,000 kg
*per batch for standard sizes and treatments
We look forward to hearing from you!
Please use our contact form or contact our sales team directly.
Silvio Stranek
Sales, Technical Consulting / Quotes (Upper Austria, Tyrol, Salzburg, Vorarlberg, Bavaria, South Tyrol)
Email. s.stranek@htr.at
Phone: +43 (0) 664 / 88 92 78 10
Thomas Stadlober
Sales, Technical Consulting / Quotes (Styria, Vienna, Lower Austria, Carinthia, Slovenia)
Email. t.stadlober@htr.at
Phone: +43 (0) 664 / 88 64 15 06
OTHER ANNEALING PROCESSES
Soft annealing
In soft annealing, a steel material is typically heated to just below the so-called A1 transformation point in order to achieve low strength and high ductility.
Back to overview
OUR INDUSTRIES
Automotive industry
Aerospace
Medical technology
Tool and Machine Manufacturing
Your Questions, Answered
We have compiled a list of frequently asked questions to help you better understand our services.
What is stress-relief annealing?
Stress-relief annealing is a heat treatment process for steel components designed to specifically relieve internal residual stresses. These stresses often arise during previous manufacturing or machining steps and, if left untreated, can lead to warping or dimensional deviations.
When is stress-relief annealing required?
This process is particularly useful following operations such as casting, welding, or forging, as well as after intensive machining such as milling, turning, or deep drawing. Stress-relief annealing is an important intermediate step, especially for components with strict dimensional and geometric requirements.
What are the benefits of stress-relief annealing?
Relieving internal stresses improves the dimensional and geometric stability of the components. This significantly reduces the risk of warping during subsequent machining or heat treatment steps.
Does stress-relief annealing affect hardness or microstructure?
Stress-relief annealing has no specific effect on the material microstructure and alters the hardness only slightly. The focus is exclusively on reducing internal stresses, not on adjusting the mechanical properties of the material.
At what temperatures is stress-relief annealing performed?
Stress-relief annealing is typically performed at temperatures between 550 and650 °C with a holding time of about two hours, depending on the material and component dimensions.
Why is slow cooling important?
Controlled, slow cooling in the furnace prevents the re-formation of stresses caused by temperature gradients. This is particularly important for large or solid components.
Is stress-relief annealing necessary before further heat treatments?
Yes, a low-stress condition is particularly important prior to thermochemical processes such as nitrocarburizing in order to ensure dimensional stability, process reliability, and reproducible results.