Pickling salts

izafireman

izafireman

Well-Known Member
Having just had some stainless heat treated in a salt bath the heat treaters (I think ) did not neutralise the salts and so the blanks were quite rusty and pitted when I received them. I am cleaning them in pickling salts at the moment which seems to be doing the trick with the rust but it occurred to me does anyone ever use this method on a finished blade? I was just wondering how it would look , maybe something like 'flat' dull finish?

Anyone ever used them for this?
 
izafireman said:
Having just had some stainless heat treated in a salt bath the heat treaters (I think ) did not neutralise the salts and so the blanks were quite rusty and pitted when I received them. I am cleaning them in pickling salts at the moment which seems to be doing the trick with the rust but it occurred to me does anyone ever use this method on a finished blade? I was just wondering how it would look , maybe something like 'flat' dull finish?

Anyone ever used them for this?
Click to expand...
You got rusted blades back from a heat treating service? Is that normal?
 
I'm with opaul. That doesn't sound normal. Have you talked to the heat treater about it?

I've heard of using pickling salts before, but I don't know how the results are supposed to turn out
 
I'd be a bit upset about rusty blades returning from the heat treater....... that tells me the outfit either doesn't know what it's doing (and if so how could you trust the heat treat), or doesn't care. Neither is acceptable IMO.
 
I've never heard of heat treating stainless in a salt bath, maybe I'm missing something but knives shouldn't come back from a heat treat with anything other than discoloration or maybe some mild scale, not chemical after affects, or rust.
can you post pictures of the knife ?
 
I was speaking to Uddeholm and for many of their steels it is the preferred method of heat treating as the the molten salt is by far best medium for direct heat transfer into the steel . They might even quench in salts at a lower temperature but I'm But not in all situations It is normal to get a slight rusting on the surface but my steel was quite rusty as I don't think the salts had been neutralised.

I'm not sure which salts are used for the heat treat but believe sodium nitrate and potassium nitrate are used for tempering cycles as they melt at around 160 c

Heres a link to Uddeholm heat treating in molten salt. Oh and you can get molten salt baths for home use of course.


Oh and I just read that's sodium nitrate with potassium chloride are the salts for austenising.

 
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izafireman said:
I was speaking to Uddeholm and for many of their steels it is the preferred method of heat treating as the the molten salt is by far best medium for direct heat transfer into the steel . They might even quench in salts at a lower temperature but I'm But not in all situations It is normal to get a slight rusting on the surface but my steel was quite rusty as I don't think the salts had been neutralised.

I'm not sure which salts are used for the heat treat but believe sodium nitrate and potassium nitrate are used for tempering cycles as they melt at around 160 c

Heres a link to Uddeholm heat treating in molten salt. Oh and you can get molten salt baths for home use of course.

Click to expand...

Here's another link


 
Sean Jones said:
I'm with opaul. That doesn't sound normal. Have you talked to the heat treater about it?

I've heard of using pickling salts before, but I don't know how the results are supposed to turn out
Click to expand...

Yes is pretty normal to have a small amount of rust but my batch were rusted badly. To be fair the owner heat treaters want to know more about the issue as I don't think he has seen the steel.
 
Well I have been doing a bit of digging today with other heat treat companies and they have told me that the 'salt bath' method of meat treating is a fantastic method as the medium once at temperature is bang on the money. They also said they will be no corrosion so long as the steel is tempered quickly, hence my post above is incorrect. They said that the steel sounds like it might have been through more than one cycle as they might not have used a 'fast bath' which can hit 1080c or they left the steel lying around with salts on it.

I wanted to clear this up as obviously there are people who sell salts baths, not sure if the Boss does, but they are a superb bit of kit and a favourite in industry.

With regards to my situation its pretty clear someone made an error and luckily the heat treaters have said they want to resolve the situation that occurred which was their fault.

Once this is sorted I will post a few images of the issue.
 
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