Analyse or Measure Spring Steel Wire Rod Pickling Quality!

The only real way to do it is to do some bench-top trials at different concentrations and assess the outcome.

Thanks but how to access the outcomes?? thats my question....

Determine the desired outcome and the deviation limits from that outcome.

If it's spring wire, presumably you want to measure it's deflection under a known load?
Or is it surface finish you are interested in?
Del

Exactly. The desired outcome of the pickling process needs to be determined, nay quantified, with tolerance limits. Once that is done, in goes Statistical Process Control.

Why it is required to be pickled the wire? Where these springs are intended to be used?

Pickling forms a protective surface which may get damaged while making coils for spring. It can be done off-line or in-process. Normally 3 steps are followed:

1. Cleaning with caustic solution

2. Acid pickling

3. Phosphating

For doing it off-line three parameters (individually for above 3 steps) are to be maintained; concentration, bath temperature and time of dipping to get desired pickling result. There are only general standards available. Above parameters specific to the job can be decided by specialist service provider, Please contact them.

For doing it in-process, change in concentration may be taken as deciding factor, again decided by specialist service provider.

not all springs are corrosion resistant. it depends on the alloys used.

You have another important issue. You have not mentioned about hydrogen embrittlement.

Spring steel is sensitive to hydrogen embrittlement. Hydrogen absorption must be minimized during pickling and other pre-treatments.

Bake-out ('de-embrittlement') of hydrogen absorbed during plating must begin within a short time (preferably within 1 hour) of plating.

ISO 9588 'Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement' gives more hydrogen bake-out details.

It is too late to make springs from corroded wire !!

You should order/produce spring wire by grinding the OD and keep it in corrosion retarding oil/cover

Cleaning springs after winding-you should do with alcali solutions and water washing+drying in 80-100 Celsius (1-3 minutes each stage)

If you have allready corrosion;springs will perform poorly due to surface damage causing cracks and early spring failure

The best test to check spring performance is by functional spring cycle deformation

(special machinery exist for this purpose)

You will have to establish chemical limits for the solution and test it periodically in the lab.

Where's your process engineer?

If you don't have one, you'll just have to guess at it.

First, define your current process: How is the solution made? How is the wire prepped? What ion concentrations? How long is wire immersed? What temperatures? What are the characteristics of the wire after the process is complete? If you don't know your current process well, you won't know when it changes.

Second, make one change: What are the characteristics of the wire after the altered process is complete?

Use an appropriate statistical hypothesis test such as ANOVA (Analysis of Variance). Suggested test hypothesis: There is no difference between the 2 treatments.

the information you need is on the AGA " American Gavinizers Association" web site.

or do test studies with an oxidizer.