Material Toughness comparisons

[mschro]

Hi,

We have a shear shredder operating in a difficult application where it is shredding mild steel with a somewhat thin cross-section (3/16" minus). The cutters in the shredder are general purpose blades made from 4140 heat treated to 52-55 RC. The blades are seeing both rapid wear and chipping/breaking of the teeth. We are considering changing to a tool steel blade. The breaking of the teeth has us considering S7 and high wear has us considering A2.

The difficulty we are having is comparing the relative wear resistance of each material and relative toughness of each material in their heat treated condition - in comparison to the current 4140 material.

Is there a chart that anyone can recommend for performing this comparison. Is there any general recommendation anyone can make for this application?

Thanks

 

Hardened 4140 'general purpose' steel appears inadequate for what is a brutal application.
The chipping you are seeing is not a lack of fracture toughness but probably strain hardening of the cutting edges to the point of exhaustion of ductility. (Although I would want the blades to have some level of toughness.)
This definitely looks like a job for a tool steel, although I can't give an accurate recommendation.
Suggest you go to the ASM Handbook; it will describe typical uses for every tool steel grade, as well as appropriate heat treatments.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[WKTaylor]

Some interesting info, may/may-not be useful, this subject in following document...

SAE J965-Jan2018 Abrasive Wear

Regards, Wil Taylor

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[Maui]

You would be best served in this type of application by using a good quality high speed steel. My recommendation would be CPM M4. You can read about it, along with many other choices, here:

https://www.crucible.com/eselector/prodbyapp/highspeed/highspeedapptitle.html

Maui