Stress Relieving
Stress relieving heats parts to a moderate temperature, typically 550–650 °C for steel, holds and cools slowly to reduce residual stresses from welding, machining or forming. It prevents later distortion and cracking without significantly changing hardness.
What it is
Welding, heavy machining and cold forming leave internal stresses that can make parts move after final machining or crack in service. Heating below the transformation range lets these stresses relax.
It is standard between rough and finish machining of weldments and castings, and for welded structures under codes.
Typical applications
- Welded frames and fabrications before machining
- Machine beds and castings
- Heavily machined parts
- Pressure vessels and pipework (as per code)
- Cold-formed components
Suitable materials
- Carbon and structural steels
- Alloy steels
- Cast iron
- Stainless steel (with care)
Points to consider
- Plan it between rough and finish machining for stable precision parts.
- Hardened parts should be stress relieved below their tempering temperature.
- Large weldments need furnaces of suitable size.
- Support parts in the furnace to avoid sagging.
Frequently asked questions
Why stress relieve welded parts?
To remove welding stresses so the part doesn't distort during machining or crack in service.
Does stress relieving change hardness?
Only slightly, because temperatures stay below the transformation range.
When should stress relieving be done?
Usually after welding or rough machining and before finish machining.