Stainless Tool Steel

[PhilBW]

I have an application that requires the wear resistance of a tool steel, but also needs the corrosion resistance of stainless steel. I have been able to find suitable materials, but they are all powdered metal. The shape and size of the parts don't lend themselves well to molding and sintering, which means I will pay a premium for powdered metal bar stock and then machine a bunch of it away.

I understand that using powdered metal keeps the carbides evenly dispersed. My question is why are there so many mild steel wrought tool steels available, but when you switch to stainless the only thing available is powdered metal?

Phil

 

[btrueblood]

AISI type 440 stainless is fairly wear resistant.

There are lots of lower alloy tool steels available, because cheaper is better (why use all that expensive chrome if you don't need it?). And for most stainless steel applications, the brittle nature of the 440 series can be detrimental (it makes a lovely knife, up until you chip the blade).

 

[dgallup]

D2 is "almost" stainless, might offer enough corrosion resistance if the environment is mild enough.

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[Goahead]

The complete designation is AISI type 440C

http://www.welding-advisers.com/

 

[TVP]

Have you investigated Kolsterising a conventional austenitic stainless steel in order to achieve surface hardness equivalent to hardened tool steels? Or a knife grade of stainless steel like BG42 from Latrobe?

http://www.kolsterising.bodycote.com/

http://www.latrobesteel.com/assets/documents/datasheets/BG42.pdf

 

[btrueblood]

"The complete designation is AISI type 440C"

Right. Unless you want 440B or 440A. Or 440F.

 

[StoneCold]

What about coating a low alloy tool steel to get your corrosion resistance?

StoneCold

 

[PhilBW]

I really appreciate all the suggestions.

We have used 440C and gotten pretty good results, but thought something with even more carbides would last even longer. We also have used D2 in other applications and it is very good, but this is a particularly corrosive environment. We might give it a try, though, and see what happens.

I also want to follow up in more detail on the other suggestions. I took just a quick look and they look promising.

Thanks for all your help.

Phil

 

[Maui]

Phil, there are a large number of conventionally produced stainless tool steels that are commercially available. But you need to give us a little bit more information in order to provide you with some appropriate choices. What, specifically, is the corrosive environment? What is the hardness range that the material must satisfy? Does 440C or D2 that falls within the hardness range you specified provide you with adequate wear resistance, or do you need a material that has better wear characteristics? Is toughness a concern? Answering these questions will help us to narrow down the possible choices.

Maui

http://www.EngineeringMetallurgy.com

 

[PhilBW]

The material is used in a process for cooking cereal grains and flours, many of which are abrasive. Typical process temperature is 300-400° F. Steam and water are added, and up to 1.5%hydrochloric acid, sulfuric acid and/or phosphoric acid are added as well as salt at up to 1.5%.

We have used 440C hardened to Rockwell C of 54-58. This gives a pretty good balance between hardness and toughness. The 440C gives us pretty good results, but we are always looking for something better.

Thanks in advance for any suggestions.

Phil

 

[dgallup]

To get back to your original question, I think the reason these more exotic stainless tool steels start with the powders is the manufactures find it gives better homogeneity in the steel. I think with the high concentrations of the various components they can't produce a consistent product otherwise.

To quote Crucible:
"The process lends itself not only to the production of superior quality tool steels, but to the production of higher alloyed grades which cannot be produced by conventional steelmaking."

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