Tungsten in medium carbon steel

[Greenleader]

Would the addition of tungsten, .55%, to 4340 mod, (300m),contribute a few points of hardness after tempering to spec?

I would like to add a little hardness without sacrificing strength or toughness or reducing the draw temp.

 

[Goahead]

It is true that tungsten addition to steel may decrease the extent of softening during tempering. However, depending on application and size at the time of heat treatment, the same effect could possibly be obtained by the addition of lower cost alloy elements.
What about 4345?

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

 

[swall]

What hardness are you looking for?

 

[Greenleader]

Looking for low 60's Rc @575F draw.

The particular alloy is actually 4350 mod. so it's still med carbon.

 

[EdStainless]

W would increase hardness by resisting temper. This would leave you with less toughness. Why not use a slightly lower temper temp?

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[swall]

You're going to need more like a 350F or 375F draw.

 

[arunmrao]

What is the application that you intend to use for? Tungsten price has nearly doubled over the past year and is not stable . Instead why not increase the Cr levels?

 

[unclesyd]

I second arunmrao's post about the end use of the material. Where we consistently wanted hardness in this range we make out parts from tool steels, mainly air hardening. This way we get a get a better part, normally with the added ease of heat treatment.

To get 4340 per se you will have to use a polymer quench and if the part has any intratcies this could be problem with cracking. At the higher hardness 4340 has low impact values.

 

[Greenleader]

Thanks for the responses.

I happened to have some free W.
I was not sure if tungsten resisted tempering, or it just uped' the average carbide hardness.
Thanks.

 

[TVP]

In general, W is a significant carbide former, and its carbides are very hard. It also increases high temperature strength (resists softening during tempering) and wear resistance. It is usually an alloy component of hot work or high speed tool steels. The following article describes the effect of various elements on tempering, secondary hardening, etc.:

http://www.key-to-steel.com/Articles/Art128.htm

 

[arunmrao]

I support TVP's statement regarding stability of WC.

This property is made use of in design of roll guides . The guides are in constant contact with the material ,i.e abrasion and high temperature. The guides should not wear out fast as this could result in "cobble".

I produce an alloy for this application. It has 1.8% C, 18% Cr,1.5% W,0.6%Va oil quench and double tempered .

 

[Greenleader]

Interesting.
right now i'm experimenting with medium carbon, as I am after 100% lath martensite, for strength and tougness, with the nickel adding impact resistance. I'm just a little weak on the hardness. I need a tough 60Rc, using the chemistry close to 300m.

 

[NickE]

I was going to say, greenleader, you might try S7.. although that is the highest hardness I think you can get.

 

[TVP]

Greenleader,

Take a look at the following steel compositions:

http://www.edelstahl-witten-krefeld.de/upload/binarydata_ewkinterd4cms/1222/thyrodur_2721_uk.pdf

http://www.edelstahl-witten-krefeld.de/upload/binarydata_ewkinterd4cms/1224/thyrodur_2767_uk.pdf

These are the highest Ni tool steels that are typically used. Increasing the Si and W would certainly increase the temper resistance, so high temperature tempering should keep the hardness up. Off the top of my head, I do not know if the toughness of this type of alloy (additions of Si & W with high Ni) would be seriously compromised to the point where you might just use a typical tool steel hardened to 60 HRC like M2 (powder metal version). Also, there are some advanced PM tool steels like Micro-Melt PD#1 from Cartech that have much improved toughness at 59-60 HRC vs. conventional PM grades like M2, A11, etc.

 

[CoryPad]

How about AerMet 100, AerMet 350 or AerMet-for-Tooling from Carpenter? They are much tougher than either tool steels or ultrahigh strength 4XXX steels, but won't quite reach 60 HRC.

Regards,

Cory

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