What is meaning of decarb-free in tool steels ?

It probably means the surface isn't decarbed *as you get it.* If it's A2, it's A2. It has a very specific set of components and limits in the alloy.

-- Ed Huntress

I wonder if it's also more expensive because they had to go to the trouble of machining the scale/bark off the stock...

Regards,

Robin

It may be debarked, but any commercial heat-treating setup that's adequate for A2 shouldn't produce a decarbed surface in the first place. They probably heat it in a controlled atmosphere.

-- Ed Huntress

Carbon bearing steels that are hot worked tend to have the surface carbon burned out, or the material is "decarbed". When you buy decarb free material, you're buying material that has been further processed, usually machined, to remove the zone that has lost its carbon content. Without eliminating the surface material, it often won't heat treat properly because of the lower carbon content.

If you do not have a controlled atmosphere furnace, there's almost no way around using the stainless bag material if you intend for your parts to not experience further decarburization, or scaling.

Harold

A thin layer of copper plate can be used, IIRC--apparently, this acts as a barrier that the carbon wont readily pass through.

But I might be wrong on this one--Im recalling process control where a certain amount was removed ( milled away ) on carbon steel alloy forgings to remove hi carbon scale...

Then pretty sure that anything that went into the electric furnaces was plated beforehand, where with gas furnaces, and IF the Co2 levels could be controlled, then the plating wasnt needed......

I can't remember all the details anymore, but the copper plate did definately play some role here.

"PrecisionMachinisT" wrote in news: snipped-for-privacy@scnresearch.com:

I've seen that done in Nitriding, where the part is plated, then the plating is machined off in the area to be nitrided. After nitriding the rest of the plating is stripped off.

Dan

This one answers it! Thanks a lot ...

I have a home-made heat-treating oven (see my post on the subject if interested) - it goes to about 2000F, is Omega-controlled and dirt-cheap to make, runs off 110V.

It doesn't have controlled atmosphere, so when heat-treating A-2 I do use SS bags/envelopes (McMaster is one source, MSC probably carries it too). Sharp crease and a strip of brown bag paper put inside of the envelope take care of not letting much of oxygen to get in contact with the steel.

Harold and Susan Vordos wrote:

Without

Welcome!

Harold