W Solution treatment
Solution treatment · Tratamiento térmico · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “1.4301 solution annealed 1050 °C · water quench” states a solution treatment requirement.
What controls
Heating to a high temperature to dissolve the phases and precipitates present into the matrix, followed by rapid cooling that keeps them in solution. In austenitic stainless steels it leaves the material homogeneous with its corrosion resistance restored, especially after welding or forming. In precipitation-hardening alloys it is the first stage: the part is left relatively soft, awaiting the aging treatment that will give it its final properties.
How to verify
Hardness tester to confirm the material is in the expected soft condition, and a heat treatment certificate stating temperature and quench medium. In stainless steels, when the requirement is corrosion-related, verification is a specific intergranular corrosion test on a specimen, not a hardness reading. In precipitation-hardening alloys, this step is controlled as an intermediate stage and what is certified at the end is the aged condition.
Common mistakes when interpreting it
- Expecting the material to harden: solution treatment leaves the part soft; hardening comes later in the alloys that allow it.
- Accepting the treatment based on appearance, when what is usually at stake is corrosion resistance or the subsequent aging.
- Machining to final size before a rapid quench that is going to move the part.
How to get it in the workshop / if it comes out of tolerance
In austenitic stainless, the goal is corrosion resistance, not hardness: the material does not harden with this treatment and is still gummy to machine. In precipitation-hardening alloys, machine in the solution-treated condition whenever you can, because after aging the part is much harder. Rapid cooling introduces stresses and causes distortion: leave stock.
Cooling too slow: in stainless steels it allows exactly the precipitation you wanted to avoid, and in precipitation-hardening alloys it ruins the subsequent aging; the cycle must be repeated. Distortion from the rapid quench: machine afterwards or leave stock. Surface oxidation or discoloration: process run in an unprotected atmosphere; on stainless, pickle or passivate to restore the surface.
Related symbols
Other symbols in Heat treatment
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