stress relieving
what is stress relieving?
Stress relieving is a heat treatment process that aims to reduce or relieve stresses in workpieces caused by thermal or mechanical processing.
For example, stresses can occur in the material during uneven cooling after the prefabrication process (forging, rolling, etc.), mechanical processing and heat treatment. These stresses can be released during further processing and especially during heat treatment at higher temperatures, leading to dimensional changes. To prevent this, the existing residual stresses are significantly reduced during stress relief annealing. This is a special annealing process in which the basic properties of the material should not be significantly changed.
stress relieving process
The residual stresses in the material can only be relieved by plastic deformation in the micro range. During annealing, the yield point and the maximum tensile strength are reduced for the duration of the heating process, allowing the stresses to be relieved. For steel, the temperature range of the process is between 550 °C and 650 °C and the heating and cooling is carried out very slowly. This is the only way to avoid dimensional changes, cracks or new stresses in the component.
benefits to stress relieving of metals
The purpose of stress relieving is to largely reduce or at least minimize residual stresses of the first type and, in some cases, the second type, so that components remain non-destructive during further processing or in case of application and no significant dimensional changes occur.
- Relatively low annealing temperature, therefore no significant structural changes
- No significant pre-treatment necessary
- No build-up of new residual stresses
suitable materials for stress relieving
Stress relieving can be carried out on almost all metallic ferrous materials.
application of stress relieving in various industries
Typical components that benefit from stress relief annealing are large and complex welded assemblies, components with many processing steps or cast parts with large cross-sectional differences. Therefore, mold making, large machine construction and forging are the industries that benefit most from the process.
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frequently asked questions – stress relieving
Where is stress relief annealing used?
On many welded constructions, components with large cross-sectional transitions and components with a high residual stress potential due to upstream production steps.
What are the benefits of stress relief annealing?
To reduce residual micro-stresses without significantly changing the mechanical properties.
How does stress relief annealing work?
During stress relief annealing, the components are slowly heated and cooled down again so that no new residual stresses arise. The treatment temperature is usually between 550 °C and 650 °C. The holding time depends on the component thickness, but should be at least 1 to 2 hours.
Can stainless steel be stress-relieved?
As a rule, of course. You should only clarify in advance which stainless steel you are dealing with. The respective treatment parameters can be found in the steel key or the material manufacturer’s data sheets.
How is the stress relieved during stress relief annealing?
The processes that take place in the crystal lattice during stress relief annealing are associated with crystal recovery.
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