How could I improve the lifetime of induction hardened cutting edges? 4

[coreman73]

I have some cutting blades which were investment cast from steel grade 4068 (not sure of the specific composition). The cutting edge have been induction hardened to 58-60 HRC.

As an experiment, I want to increase strength/durability in order to allow for a longer lasting cutting edge. Since investment casting was used, the supplier has mentioned that the chemistry can be tailored however we request. What specific elements would accomplish this (only interested in tweaking Cr, Ni and Mo levels) and how could I determine how much of them to add? Of course, I do not want to increase toughness at the expense of hardness.

For example, I am considering possible alternative steel grades 4168 as well as 4360 or 8660. Would these be better choices over the 4068?

Any advice is most appreciated.

 

[Metalguy]

I'd start by determining if the cutting edges have been tempered after ind. hardening. The addition of Ni is a good thing (43xx series).

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[arunmrao]

If you can afford add some Co,V and W, they will improve the blade life. Finally try subzero treatment. you can also try ceramic coating on the blade tip.

_____________________________________
"The richer we have become materially, the poorer we have become morally and spiritually." Martin Luther King Jr

 

[coreman73]

Metalguy,
Yes, the cutting edges have been tempered after induction hardening. I will consider the 43xx series as the best of my alternatives since they do have a relatively high level of Ni for increasing toughness. Could there be any potential issues reaching 58-60 HRC with this type of steel?

arunmrao,
I will consider those element additions. Is the ceramic coating expensive that you know of? Maybe you meant this when you said "if you can afford it"?

 

[redpicker]

See what you can do for inclusion control. The smaller, the better. While alloy content has a strong effect on the wear, the inclusions product small 'nicks' in the shaprened edge. If the size of the inclusions is greater than the radius of the edge, the inclusions will have a greater effect than the alloy content.

rp

 

[Metalguy]

Although it doesn't contain Ni, you might consider the use of S7 tool steel. A very tough and hard steel.

http://webcache.googleusercontent.com/search?q=cache:KDcl1TNAYegJ:

http://www.simplytoolsteel.com/S-7-...d=1&hl=en&ct=clnk&gl=us&source=www.google.com

"You see, wire telegraph is like a very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? Radio operates the same way: You send signals here, they receive them there. The only difference is there is no cat." A. Einstein

 

[arunmrao]

coreman73 My apologies for using the phrase " if you can afford it". Normally,we use this term to justify the cost against the service life and in no way was it a personal affront.

Since you mentioned that they were investment cast and you could prepare the recipe, I thought of recommending those performance enhancers.

Yesterday I looked at some kitchen knives they were made of ceramics,while another from Japan,had all the elements that I recommended, but made by P/M technique. I am unable to recall the brand,I will try and search for it.

_____________________________________
"The richer we have become materially, the poorer we have become morally and spiritually." Martin Luther King Jr

 

[blacksmith37]

I suggest you determine what your problem is first; since you are starting with such a "lean" steel , almost any steel will give some sort of improvement.
If wear/dulling is a problem , try 52100 or any high C tool steel (S series, O series, etc).
If cracking is a problem try Ni like 4360 or S series (shock resistant)tool steels.

 

[coreman73]

arunmrao,
Oh, I didn't take it personally at all. I just really thought by afford that you were literally referring to cost. If that was the case then the company would be paying anyway so no big deal to me. haha I appreciate your comments very much.

 

[coreman73]

blacksmith37,
There isn't a problem as of now. This was just a hypothetical question really. I do agree though that nearly any steel would give an improvement. I will do some testing with the 4360 and S tool steel for comparison.

 

[coreman73]

I just have one final question. Are any of the steels mentioned (43xx series, 86xx series, S7 tool steel) likely to be negatively affected by investment casting? Basically, is there any reason to believe a particular steel would not be an adequate candidate for the investment casting process?

 

[blacksmith37]

When I was a boy working in an investment foundry; we poured a lot of 8620 , some 4140, O1, S7, (and 310 ss, 410, 17-4,Stellites, etc.). I did not know why selections were made ,except we quoted 310 lower than 304 because it was easier to pour.And we avoided carbon steel.

 

[EdStainless]

Another surface treatment is TiC, they react a Ti containing gas with the hot parts and it reacts with the C in alloy to form an integral TiC surface layer.

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Plymouth Tube

 

[tomwalz]

Edge shape or configuration? Finish polish? Hone?

Super Thin Saws was bought by a coater with a new technology.

John Schultz, there, is a great tool guy. 1.800.541.7297
Try to get him if you can.

Stellite coating?
Louw De Jong
Stoody Deloro Stellite
604 463-2140
ldejong@stellite.com

Tru cut Saw does coating and knows an awful lot about cutting.
Tru-Cut Saw, Inc.
2903 Interstate Parkway
Brunswick, Ohio 44212 USA
Phone: 330-225-4090
Toll Free: 800-878-8761
Fax: 330-225-4741
E-mail: trucutsaw@trucutsaw.com

Tom Walz

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.